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Effect of Drip Irrigation on Strawberry Growth and Yield inside a Plastic Greenhouse
ARTICLE IN PRESS Biosystems Engineering (2004) 87 (2), 237–245 doi:10.1016/j.biosystemseng.2003.10.014 SW}Soil and Water
Available online at www.sciencedirect.com
Effect of Drip Irrigation on Strawberry Growth and Yield inside a Plastic Greenhouse B.Z. Yuan1; J. Sun2; S. Nishiyama2 1
The United Graduate School of Agricultural Sciences, Tottori University, Japan; e-mail of corresponding author: [email protected] 2 Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi, 753-8515, Japan; e-mail: [email protected]; [email protected] (Received 24 April 2003; accepted in revised form 17 October 2003; published online 23 December 2003)
Effects of drip irrigation on the growth and yield of strawberries were studied inside a plastic greenhouse. The amounts of irrigation water applied were 075, 100 and 125 times water surface evaporation (Ep) measured by a standard 200 mm diameter pan, and the corresponding regimes were denoted Ep075, Ep100 and Ep125. During the experimental period, soil moisture tension of regimes Ep100 and Ep125 at 02 m depth varied from 5 to 17 kPa, and varied from 5 to 23 kPa at 04 m depth; but soil moisture tension of regime Ep075 at 02 m depth changed from 65 to 43 kPa, and soil moisture tension at 04 m depth had been over 70 kPa at the end. Plant leaves, flowers and fruits, above-ground biomass, runners, total berry yields, marketable strawberry yields (>5 g), the size of strawberry fruits all increased when the amount of irrigation water increased from Ep075, Ep100 to Ep125. Irrigated water increased strawberry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. The trends of the irrigation water use efficiency for the plant biomass and the production of total fresh berry yields showed that the lower the amount of irrigation water received, the higher the irrigation water use efficiency. Based on the experimental results, the optimal amount of irrigation water is about 380 mm, the optimal pan factor is about 11 and the optimal irrigation water use efficiency for strawberry yield is about 163 g mm1 for strawberry growth and yield inside a plastic greenhouse. So, strawberries grown inside plastic greenhouse should be irrigated using a pan factor of 11 as a guideline for irrigation during the full growth seasons. The use of a lower pan factor may reduce the berry yield significantly. # 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd
1. Introduction The development of greenhouse culture has expanded and is widely used in Japan. Almost 80% of greenhouses are of sheet plastic, and are usually used in the sideopening condition (Haraguchi et al., 2000). Most strawberries are planted inside plastic greenhouses for berry production in Japan. Plastic mulches over trickle irrigation systems are widely used in raised-bed culture of strawberry to save water, to control weeds with less use of herbicides, to keep fruits clean, to increase the fruit size and yield and to enhance earliness and fruit quality. Black is the most widely used colour of plastic mulch (Blatt, 1984; Baumann et al., 1993; Kasperbauer, 2000). Strawberry plants on raised beds have a deeper, more uniform root distribution, indicating a more 1537-5110/$30.00
favourable environment for root growth as compared to flat beds (Albregts et al., 1991, 1996; Dwyer et al., 1987; Goulart & Funt, 1986; Hochmuth et al., 1996; Kru. ger et al., 1999). Scheduling water application is very critical to make the most efficient use of drip irrigation system, as excessive irrigation reduces yield, while inadequate irrigation causes water stress and reduces production. The optimal use of irrigation can be characterised as the supply of sufficient water according to plant needs in the rooting area, and at the same time, avoiding the leaching of nutrients into deeper soil levels (Kru. ger et al., 1999). High frequency water management by drip irrigation minimises soil as a storage reservoir for water, provides at least daily requirements of water to a portion of the root zone of each plant, and maintains a high soil matric 237
# 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd
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potential in the rhizosphere to reduce plant water stress. On the other hand, the intensity of the operation requires that the water supply is kept at the optimum to maximise returns to the farmer. A widely adopted method for estimating crop consumptive water use (CWU) is the evaporation pan method, which relates evaporation from a Class A evaporation pan to CWU. These two quantities are related by what is called the crop coefficient K. Irrigation scheduling based on the crop coefficient K is one of the simplest methods where no sophisticated instrument is required. Precise values for K are often difficult to establish, given regional and site-specific, soil characteristics, crop physiology, and cultural practices. Any recommended value of K for a regional irrigation scheduling programme must be high enough to prevent water stress arising from emergencies and specialised local situations, while remaining low enough for efficient water management. Based on the US Weather Service Class A pan evaporation, many studies have been completed on the irrigation of broccoli, carrot, rape, and cabbage (Imtiyaz et al., 2000), cucumber (Eliades, 1988; Randall & Locascio, 1988), tomato (Locascio & Smajstrla, 1996) and potato (Ferreira & Carr, 2002; Panigrahi et al., 2001). The standard 200 mm diameter pan is a common instrument used to observe the water surface evaporation in China (Yuan et al., 2001) and in Japan (Yuan et al., 2003) and is equivalent to the US Weather Service Class A pan. Therefore, applying water by drip irrigation in relation to the amount of water evaporated from a standard 200 mm diameter pan would be also a convenient method to schedule irrigation, as standard 200 mm diameter pan evaporation data are relatively easy to obtain, though good pan evaporation data require careful measurements and frequent maintenance. The objectives of this study were: (1) to find the effects of water application amount during drip irrigation on strawberry growth and yield; (2) to find relationship between the water requirements of strawberry and a standard 200 mm diameter pan evaporation; and (3) to find the optimum value of crop coefficient K for drip irrigation scheduling of strawberry under controlled conditions.
2. Material and methods The experiment was conducted inside one plastic greenhouse at the farm of Yamaguchi University (latitude 348090 N, longitude 1318270 E and altitude 20 m above sea level) from November 2000 to June 2001. The plastic greenhouse was made of a steel frame
and covered by 01 mm thick white clear polyethylene (PE) film. The climate is warm temperate, humid marine in this area. On 18 November 2000, the strawberry (Fragaria ananassa Duch. Sachinoka) were planted inside the greenhouse. The soil type is silt loam, soil bulk density for 0–01 m depth is 1150 kg m3 and for 01– 02 m depth is 1220 kg m3, and soil pH value is 64. Fertiliser was applied uniformly to each treatment when the soil was ploughed. Plants were set 03 m apart in rows with a distance of 10 m between each row. After planting, overhead irrigation was used until the plants were established using the drip tube. The strawberry was covered with 003 mm thick black polyethylene mulch, and the water irrigated by the drip tube under the mulch. There are three treatments, denoted Ep075, Ep100 and Ep125, where the water quantities applied were 075, 100 and 125 times the pan evaporation measured by a standard 200 mm diameter evaporation pan placed above the plant canopy in the centre of the greenhouse. Fresh water (pH value of 72) was applied using the drip tube with emitters 22 mm apart placed 50 mm from the plant along the row under the mulch. The amount of irrigation water in mm was based on the area of the 1 m long by 05 m wide and the strawberry crop was irrigated every 2 days. Water was poured into storage tanks (20 l ) after measuring using catch cans. The tanks were connected to drip tubes, and were covered by the polyethylene plastic bags to prevent dust contamination. Plant protection was carried out as usual for this crop. Foliar and fruit diseases were controlled with timely sprays of agricultural chemical medicine. Tensiometers (DIK, Daiki Rika Kogyo Co. Ltd.) were located between two plants in a row; with the ceramic tip 02 and 04 m below the surface in the middle of the main rooting area of the strawberries (Albregts et al., 1996; Hochmuth et al., 1996; Kru. ger et al., 1999; Sav!e et al., 1993). Tensiometers readings were recorded daily at 08:00 h in the morning. Daily air temperatures and soil temperature were measured with mercury-inglass thermometers inside the greenhouse and Weather Station approximately 100 m from experimental field every day at 08:00 and 14:00 h. The evaporation inside greenhouse was measured with a standard 200 mm diameter evaporation pan. Plants were evaluated by the number of leaves and the number of flowers (including the fruits) every week. These measurements were made so that the relative growth could be determined for plants receiving different amounts of irrigation water based on the small pan evaporation. Runners and older leaves were removed by hand and dried as they developed throughout the growing seasons. After the last harvest, plants were removed, cleaned, and dried for tissue dry-weight
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3. Results and discussion 3.1. Weather conditions Without the heating systems, solar radiation is the only energy source inside the greenhouse. Solar radiation contributes to heating greenhouse in the day, and its contribution to the total heating requirement increases if the temperature is allowed to rise in the day and fall in the night. The air temperature inside the plastic greenhouse fluctuated substantially, as well as that of the solar radiation, because the solar radiation contributes to heating a greenhouse in the day. So, the greenhouse environment conditions differed from month to month. Air temperatures and soil temperatures at 01 m depth at 08:00 and 14:00 h inside and outside greenhouse are given in Fig. 1. From December 2000 to May 2001, the average air temperature at 08:00 h for each month inside greenhouse was 24, 18, 44, 77, 124 and 1018C higher than that outside the greenhouse. From January to May, the average soil temperatures (01 m depth) at 08:00 h for each month inside greenhouse were 64, 67, 69, 64 and 398C higher than that outside the greenhouse.
40 35 30 25 20 15 10 5 0 -5 12F 12S12L 1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
Calendar period
(a) 30 Soil temperature,˚C
determinations at 858C for 48 h to measure dry matter. Then, plant biomass was calculated. Mature strawberry fruits (at least 75% red colour) were harvested twice weekly and separated into four categories for berry fruit size: >15 g, >10 g, >5 g and 55 g to determine marketable, cull, and number and weight of berry fruit on each picking date. Marketable fruits were those fruit free of rot, well-shaped (conical or flat-wedge), and weighing 5 g or more. Fruit from each harvest in each grade category were conducted and weighed. Mean fruit weight was determined by weighing each fruit on each picking date and calculated as an average fruit weight. All components and marketable yield were analysed per plant. The irrigation water use efficiency (IWUE) for plant biomass is calculated as plant dry matter divided by the total amount of irrigation water; the irrigation water use efficiency (IWUE) for strawberry yield is calculated as the production of total fresh berry yield divided by the total amount of irrigation water. Statistical analysis was by standard analysis of variance (ANOVA). The treatments were run as a single-factor ANOVA. Where appropriate, single-degree-of-freedom orthogonal polynomial contrasts were used to determine whether differences existed between certain comparisons. The probability level for determination of significance was 005.
Air temperature,˚C
EFFECT OF DRIP IRRIGATION ON STRAWBERRY
25 20 15 10 5 0 12L 1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
(b)
Calendar period
Fig. 1. Comparison of air temperature (a) and soil temperature at 01 m depth (b) inside and outside a plastic greenhouse at 08:00 and 14:00 h from December 2000 to June 2001: F, S and L are the first, second and last ten days for every month; &, inside at 08:00 h; , inside at 14:00 h; }, outside at 08:00 h; n, outside at 14:00 h
Air temperatures were monitored three times on clear days during plant growth stages. Figure 2 shows the diurnal changes of air temperature and soil temperature at 01 m depth inside and outside a greenhouse. On clear days, diurnal changes of air temperature show a steep increase in temperature after sunrise, maximum values near 14:00 h, then followed by a steep decrease with low values before the sunset. The diurnal changes in soil temperature were later than those of air temperature inside and outside greenhouse. 3.2. Water applied and water used Inside a plastic greenhouse, irrigation water is the only source of moisture to the plants and there is no rainfall and no runoff using the drip irrigation systems. If the deep percolation and changes of soil water storage before and after the experiment are not considered, evapotranspiration of the strawberries is equal to the applied irrigation water. During the experimental period, the cumulative amount of irrigation water is equal to the fractions of the cumulative pan evaporation that is affected by air temperature (Fig. 3).
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Air temperature,˚C
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45 40 35 30 25 20 15 10 5 0 -5 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 1618 20 22 Time, h
(a)
Soil temperature,˚C
30 25 20 15 10
3.3. Soil moisture tension
5 0
(b)
8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 1618 20 22 Time, h
Fig. 2. Diurnal changes of air temperature (a) and soil temperature at 01 m depth (b) inside and outside a greenhouse on clear days: }, outside on 17–18 January; &, inside on 17–18 January; n, outside on 26–27 March; , inside on 26–27 March; *, outside on 12–13 May; +, inside on 12–13 May
450 400 350 Amount of irrigation water, mm
During the growth period from 4 December 2000 to 20 June 2001, the cumulative irrigation water amounts were 2548, 3363 and 4140 mm, and the averages of irrigation water use were 13, 17 and 21 mm day1 for Ep075, Ep100 and Ep125, respectively. From Fig. 3, the strawberry growth inside greenhouse can also be divided into two stages by the amount of irrigation water. One is the period from 4 December 2000 to 20 March 2001; the amount of irrigation water is less and the averages of irrigation water use are 061, 078 and 092 mm day1 for Ep075, Ep100 and Ep125, respectively. Another period is from 21 March 2001 to 20 June 2001; the amounts of irrigation water are more and the averages of irrigation water use are 206, 275 and 343 mm day1 for Ep075, Ep100 and Ep125, respectively.
300 250 200 150 100 50 0 4/12 25/12 15/1 5 /2 26/2 19/3 9 /4 30/4 21/5 11/6 Date
Fig. 3. Cumulative amount of irrigation water based on the fraction of pan evaporation inside a greenhouse from 4 December 2000 to 20 June 2001: }, Ep075, 075 times pan evaporation; }, Ep100, 100 times pan evaporation; , Ep125, 125 times pan evaporation
From December 2000 to February 2001, the soil moisture tension at 02 and 04 m soil depth were similar for different treatments, about 5–10 kPa (Fig. 4). On reaching March, the air temperature became higher, plants grew faster and needed much soil water, and then, the applied irrigation water was insufficient to maintain the previous soil water tension. So, the soil moisture tension increased higher. From March to May, there was only the Ep075 treatment and at 02 m depth the soil moisture tension significantly changed from 65 to 43 kPa, while the soil moisture tension at 04 m depth had been over 70 kPa before the end of the May. However, the soil moisture tension of the Ep100 and Ep125 at 02 m depth only varied from 5 to 17 kPa; the soil moisture tension at 04 m depth varied from 5 to 23 kPa. During June, soil moisture tensions for three regimes at 02 m depth and 04 m depth all changed markedly and over 30 kPa. Soil moisture required by the strawberry plant in the earlier 3 months from December 2000 to February 2001 was low and soil moisture tension indicated that the soil water levels remained high from December 2000 to February 2001. Comparing the soil moisture tensions at 02 m depth [Fig. 4(a)] and 04 m depth [Fig. 4(b)] based on tensiometer values, it can be found that the changes in soil moisture tension at 02 and 04 m depth are similar, but the soil moisture tension at 04 m depth tended to be higher than at 02 m depth. So, the deep percolation and changes of soil water storage were neglected and not considered in the study. During the experimental period from December 2000 to May 2001, soil moisture tension of the Ep075 treatment significantly changed from 65 to 43 kPa, but the soil moisture tension of the Ep100 and Ep125
ARTICLE IN PRESS Soil moisture tension at 0.2 m depth, kPa
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Number of cumulative leaves per plant
100
80 70 60 50 40 30 20 10 0 12S12L1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S Calendar period (a)
Soil moisture tension at 0.4 m depth, kPa
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90 80 70 60 50 40 30 20 10
80 70 60 50
0 11/12 1/1 22/1 12/2 5/3 26/3 16/4 7/5 28/5 18/6 Date
40 30 20 10 0 12S12L1F1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
(b)
Calendar period
Fig. 4. Change in soil moisture tension at 02 m (a) and 04 m (b) depth for different treatments: F, S and L are the first, second and last ten days for every month; }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
varied from 5 to 17 kPa. In the literature, a value between 10 and 30 kPa is generally considered optimal for the growth of arable plants. In fertilisation trials on sandy soil, Hochmuth et al. (1996) used soil moisture tension between 5 and 15 kPa at 015 m depth to irrigate strawberry. Rennquist et al. (1982a, 1982b) obtained higher yield and bigger fruits in strawberries when the plants were grown at 10 to 50 kPa soil moisture tension at 02 m soil depth. Despite physiological and morphological adaptation to a water stress of 70 kPa, the strawberry cultivar ‘Chandler’ showed a higher yield when irrigation was applied to maintain a water potential of 10 kPa (Sav!e et al., 1993). 3.4. Plant development Figure 5 shows the dynamics of cumulative leaves per plant for different treatments every week from 11 December 2000 to 25 June 2001. At last, the cumulative
Fig. 5. Cumulative number of leaves per plant for different treatments from 11 December 2000 to 25 June 2001: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
number of leaves per plant for various treatments was 79, 89 and 94 for Ep075, Ep100 and Ep125, respectively. They were significant at the 005 level. The more amounts of irrigation water plot produced plants with more and vigorous leaves development. After regression analysis, they all expressed exponential growth (coefficient determination R2 > 098). Figure 6 shows the dynamic growth of flowers and berries per plant for different treatments every week from 11 December 2000 to 7 June 2001. The number of flowers and berries increased with plant growth and reached a maximum on 1 April. From April to the end of harvest, the number of flowers and berries of Ep125 and Ep100 were more than that of Ep075. That is to say, the greater amounts of irrigation water plot produced plants with more flowers and berries. During the plant growth stage, the older leaves and the new stems (new runners) were removed several times by hand, and dried for tissue dry matter determinations at 858C for 48 h. After the last harvest, plants were removed, cleaned, and also dried for tissue dry matter determinations at 858C for 48 h. Then, plant biomass was calculated. Figure 7 shows the cumulative aboveground (stems and leaves) biomass per plant. As for the leaves and flowers, the cumulative above-ground biomass has similar trends, the greater amounts irrigation water produced plants with more above-ground biomass, namely, 828, 929 and 1027 g per plant for Ep075, Ep100 and Ep125, respectively, and the
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30
affected the number of new runners, and the plots that received more irrigation water produced more new runners per plant (P ¼ 006).
25
3.5. Fruiting response
20 15 10 5 0 11/12 1/1
22/1
12/2
5/3 26/3 Date
16/4
7/5
28/5
Fig. 6. Number of flowers and berries per plant for different treatments from 11 December 2000 to 25 June 2001: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
130 120 Cumulative biomass per plant, g
110
a
100 90
a b
80
Crop yield is the most effective method of assessing economic benefits of production systems. The objective of planting any crop is to get the highest yield and the highest quality. In our experiment, strawberry harvesting stage was about 120 days from 25 February to 20 June. Figure 8 shows the dynamic changes in cumulated strawberry fruit yield per plant. There was a significant increase in total berry production as the amount of irrigation water increased from Ep075, Ep100 to Ep125. By April, air temperature was higher, plants grew faster; plant leaves, flowers and fruits increased more, and the strawberry yield also increased at the same time. From beginning to the end of the harvest, the peak harvest period was in April and May. There was neither an advance nor an elongation of the harvest period based on different treatments. For the applied irrigation water based on the pan evaporation, the total berry yield, >15 g and >5 g berry yield per plant for the treatment Ep100, are close to the treatment Ep125, and they are significantly larger than that of the treatment Ep075. The berry yield for 55 g are same for three different treatments. The maximum number of berries per plant was from Ep100, not from Ep125. Owing to the different number of berries
70 600
60 50
500
40 30 20 10 0
Ep0.75
Ep1.00 Treatment
Ep1.25
Fig. 7. Cumulative biomass (stems and leaves) per plant for different treatments: treatments Ep075, Ep100 and Ep125 denote applied irrigation water of 075, 100 and 125 times pan evaporation. Bars show the standard deviations for different treatments; letters a and b show the difference for treatment at 005 probability
Cumulative berry yield per plant, g
Number of flowers and berries per plant
35
400
300
200
100 0 20/2
differences were significant at the 005 level (probability P ¼ 004). The number of cumulative new runners was 356, 411 and 504 per plant for Ep075, Ep100 and Ep125, respectively. Different amounts of irrigation water
6/3
20/3
3/4
17/4 1/5 Date
15/5 29/5 12/6
Fig. 8. Cumulative berry yield per plant for different treatments from 20 February to 15 June: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
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Table 1 The strawberry yields per plant in g, number of berries per plant and average berry weight in g for different treatments; the treatment of Ep0.75, Ep1.00 and Ep1.25 are applied irrigation water as 0.75, 1.00 and 1.25 times pan evaporation, respectively; Av. berry weight is average berry weight per plant Treatment
Berry yield per plant, g Total
Ep075 Ep100 Ep125
b
4168 5201a 5453a
>15 g
>10 g
1270 1516 1914
b
2338 3032a 3397a
Berry number
>5 g
55 g
b
3668 4643a 4901a
Total
500 558 547
Av. berry weight, g
>5 g b
513 629 595
340 451a 427a
Total
>5 g
79 80 86
104 105 112
Note: Where significant irrigation effects were detected by the analysis of various, column means followed by the same letter are not significantly different at the 005 probability level.
600
550 Berry yield per plant, g
per plant and the large variance in fruit weights throughout the harvest period, there was no significant difference in mean fruit weight based on the total numbers (Table 1). From Fig. 8 and Table 1, it can be found that the dynamic changes in accumulated strawberry yield and the total berry yield per plant are affected by the different amounts of irrigation water. Greater the amount of irrigation water, the larger the berry yield. The increase in the amount of irrigation water also produced larger berry weight. Irrigated water increased strawberry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. In general, irrigation increased total season fruit yields, marketable yields and the number of berries, which is in good agreement with the literature (Rennquist et al. 1982a, 1982b; Sav!e et al., 1993; Kru. ger et al., 1999).
500
450
400
350
300 200
250
300 350 400 450 Applied irrigation water, mm Fig. 9. Relationship between total amount of applied irrigation water and the total fresh strawberry yield
3.6. Production function and irrigation water use efficiency In the experiment, there were various production functions concerned with the total amount of applied irrigation water relative to berry yield components. Here, the production function selected was the total amount of applied irrigation water in terms of fresh berry yield in g per plant. Figure 9 shows the relationship between the total amount of applied irrigation water and total fresh berry yield. Through non-linear regression analysis, a mathematical function was obtained: y ¼ 00081x2 þ 62036x 62599
ð1Þ
where: y is strawberry yield per plant in g; and x is applied irrigation water in mm. The crop coefficient K is irrigation water related to the evaporation from a standard 200 mm diameter evaporation pan. Based on the above mathematical function, the optimal amount of irrigation water for the maximum berry yield is about 380 mm and the optimum value of
crop coefficient K is about 11 for drip irrigation of strawberry inside a plastic greenhouse. Irrigation water use efficiency (IWUE) is the relation between yield or dry matter produced and the quantity of irrigation water. Figure 10 shows IWUE in terms of expressed total fresh berry yields and IWUE in terms of expressed dry plant biomass for each treatment. The IWUE related to the production of total fresh berry yields were 169, 163 and 136 g mm1 for Ep075, Ep100 and Ep125 regimes, respectively. The IWUE related to the plant biomass were 033, 028 and 025 g mm1 for the Ep075, Ep100 and Ep125 regimes, respectively. In general, the trends for both the IWUE for plant biomass and IWUE for the production of total fresh berry yields showed that the lower the amount of irrigation water received, higher the irrigation water use efficiency within the threshold of applied irrigation water. Considering the strawberry yield and IWUE for strawberry yield, IWUE of treatment Ep100 is optimal,
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during the full growth seasons. The use of a lower pan factor may reduce the berry yield significantly.
0.4 0.3
2.0
0.3 1.5
0.2 0.2
1.0
0.1 0.5
IWUE for plant biomass, g mm-1
IWUE for berry yield, g mm-1
2.5
0.1 0.0
Ep0.75
Ep1.00 Treatment
Ep1.25
Acknowledgements This work was supported by a grant from Ministry of Education, Culture, Sports, Science and Technology through the Japanese Government Scholarship (Japan). The authors would like to thank Professor Yaohu Kang, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, China, for his suggestions on the paper. We are also grateful to the reviewers for perceptive comments and corrections.
0.0
Fig. 10. Irrigation water use efficiency (IWUE) related to the plant biomass and the production of total strawberry yield: treatments Ep075, Ep100 and Ep125 denote applied irrigation water of 075, 100 and 125 times pan evaporation: &, irrigation water use efficiency for plant biomass; n, irrigation water use efficiency for berry yield
and the IWUE for strawberry yield production is about 163 g mm1 inside a plastic greenhouse.
4. Conclusion In the drip irrigation experiment inside plastic greenhouse, effects of different irrigation water based on the pan evaporation inside greenhouse on the strawberry growth and yield were studied. Plant leaves, flowers and fruits, above-ground biomass, runners, total berry yields, marketable berry yields (>5 g), the size of strawberry fruits all increased with the amount of irrigation water increasing, from Ep075, Ep100 to Ep125. Irrigated water increased berry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. The trends of the irrigation water use efficiency showed that the lower the amount of irrigation water received, the higher the irrigation water use efficiency obtained for the drier plant biomass and berry yields. The optimal amount of irrigation water is about 380 mm and the optimal pan factor is about 11 for strawberry growth inside plastic greenhouse. Applying water by drip irrigation in relation to the amount of water evaporated from a standard 200 mm diameter pan is a convenient, simple, easy and low cost method. Therefore, strawberries grown inside plastic greenhouse should be irrigated using a pan factor of 11 as a guideline for irrigation
References Albregts E E; Clark G A; Stanley C D; Zazueta F S; Smajstrla A G (1991). Preplant fertilization of fruiting microirrigated strawberry. HortScience, 26(9), 1176–1177 Albregts E E; Hochmuth G J; Chandler C K; Cornell J; Harrison J (1996). Potassium fertigation requirements of drip-irrigated strawberry. Journal of the American Society for Horticultural Science, 121(1), 164–168 Baumann T E; Eaton G W; Spaner D (1993). Yield components of day-neutral and short-day strawberry varieties on raised beds in British Columbia. HortScience, 28(9), 891–894 Blatt C R (1984). Irrigation, mulch, and double row planting related to fruit size and yield of ‘Bounty’ strawberry. HortScience, 19(6), 826–827 Dwyer L M; Stewart D W; Houwing L; Balchin D (1987). Response of strawberry to irrigation scheduling. HortScience, 22(1), 42–44 Eliades G (1988). Irrigation of greenhouse-grown cucumbers. Journal of Horticultural Science, 63(2), 235–239 Ferreira T C; Carr M K V (2002). Responses of potatoes (Solanum tuberosum L.) to irrigation and nitrogen in a hot, dry climate. I. Water use. Field Crops Research, 78, 51–64 Goulart B L; Funt R C (1986). Influence of raised beds and plant spacing on growth and yield of strawberry. Journal of the American Society for Horticultural Science, 111(1), 176–181 Haraguchi T; Nakano Y; Kuroda M; Hirota O (2000). Evapotranspiration in a platic greenhouse with side-openings. Transaction of the Japanese Society of Irrigation, Drainage and Reclamation Engineering, 209, 35–41 Hochmuth G J; Albregts E E; Chandler C C; Cornell J; Harrison J (1996). Nitrogen fertigation requirements of drip-irrigated strawberry. Journal of the American Society for Horticultural Science, 121(4), 660–665 Imtiyaz M; Mgadla N P; Manase S K; Chendo K; Mothobi E O (2000). Yield and economic return of vegetable crops under variable irrigation. Irrigation Science, 19(2), 87–93 Kasperbauer M J (2000). Strawberry yield over red versus black plastic mulch. Crop Science, 40(1), 171–174 Kr.uger E; Schmidt G; Bruckner U (1999). Scheduling strawberry irrigation based upon tensiometer measurement and a climatic water balance model. Scientia Horticulturae, 81, 409–424
ARTICLE IN PRESS EFFECT OF DRIP IRRIGATION ON STRAWBERRY
Locascio S J; Smajstrla A G (1996). Water application scheduling by pan evaporation for drip-irrigated tomato. Journal of the American Society for Horticultural Science, 121(1), 63–68 Panigrahi B; Panda S N; Raghuwanshi N S (2001). Potato water use and yield under furrow irrigation. Irrigation Science, 20, 155–163 Randall H C; Locascio S J (1988). Root growth and water status of trickle-irrigated cucumber and tomato. Journal of the American Society for Horticultural Science, 113(6), 830–835 Rennquist R P; Breen J; Martin L W (1982a). Vegetative growth response of ‘Olympus’ strawberry to polyethylene much and drip irrigation regimes. Journal of the American Society for Horticultural Science, 107, 369–372
245
Rennquist R P; Breen J; Martin L W (1982b). Effect of polyethylene much and summer irrigation on subsequent flowering and fruiting of ‘Olympus’ strawberry. Journal of the American Society for Horticultural Science, 107, 373–376 Sav!e R; Pe*nuelas J; Marf"a O; Serrano L (1993). Changes in leaf osmotic and elastic properties and canopy structure of strawberry under mild water stress. HortScience, 28(9), 925–927 Yuan B Z, Kang Y; Nishiyama S (2001). Drip irrigation scheduling for tomatoes in unheated greenhouse. Irrigation Science, 20, 149–154 Yuan B Z, Nishiyama S; Kang Y (2003). Effects of different irrigation regimes on the growth and yield of dripirrigated potato. Agricultural Water Management, 63(3), 153–167.
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Effect of Drip Irrigation on Strawberry Growth and Yield inside a Plastic Greenhouse B.Z. Yuan1; J. Sun2; S. Nishiyama2 1
The United Graduate School of Agricultural Sciences, Tottori University, Japan; e-mail of corresponding author: [email protected] 2 Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi, 753-8515, Japan; e-mail: [email protected]; [email protected] (Received 24 April 2003; accepted in revised form 17 October 2003; published online 23 December 2003)
Effects of drip irrigation on the growth and yield of strawberries were studied inside a plastic greenhouse. The amounts of irrigation water applied were 075, 100 and 125 times water surface evaporation (Ep) measured by a standard 200 mm diameter pan, and the corresponding regimes were denoted Ep075, Ep100 and Ep125. During the experimental period, soil moisture tension of regimes Ep100 and Ep125 at 02 m depth varied from 5 to 17 kPa, and varied from 5 to 23 kPa at 04 m depth; but soil moisture tension of regime Ep075 at 02 m depth changed from 65 to 43 kPa, and soil moisture tension at 04 m depth had been over 70 kPa at the end. Plant leaves, flowers and fruits, above-ground biomass, runners, total berry yields, marketable strawberry yields (>5 g), the size of strawberry fruits all increased when the amount of irrigation water increased from Ep075, Ep100 to Ep125. Irrigated water increased strawberry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. The trends of the irrigation water use efficiency for the plant biomass and the production of total fresh berry yields showed that the lower the amount of irrigation water received, the higher the irrigation water use efficiency. Based on the experimental results, the optimal amount of irrigation water is about 380 mm, the optimal pan factor is about 11 and the optimal irrigation water use efficiency for strawberry yield is about 163 g mm1 for strawberry growth and yield inside a plastic greenhouse. So, strawberries grown inside plastic greenhouse should be irrigated using a pan factor of 11 as a guideline for irrigation during the full growth seasons. The use of a lower pan factor may reduce the berry yield significantly. # 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd
1. Introduction The development of greenhouse culture has expanded and is widely used in Japan. Almost 80% of greenhouses are of sheet plastic, and are usually used in the sideopening condition (Haraguchi et al., 2000). Most strawberries are planted inside plastic greenhouses for berry production in Japan. Plastic mulches over trickle irrigation systems are widely used in raised-bed culture of strawberry to save water, to control weeds with less use of herbicides, to keep fruits clean, to increase the fruit size and yield and to enhance earliness and fruit quality. Black is the most widely used colour of plastic mulch (Blatt, 1984; Baumann et al., 1993; Kasperbauer, 2000). Strawberry plants on raised beds have a deeper, more uniform root distribution, indicating a more 1537-5110/$30.00
favourable environment for root growth as compared to flat beds (Albregts et al., 1991, 1996; Dwyer et al., 1987; Goulart & Funt, 1986; Hochmuth et al., 1996; Kru. ger et al., 1999). Scheduling water application is very critical to make the most efficient use of drip irrigation system, as excessive irrigation reduces yield, while inadequate irrigation causes water stress and reduces production. The optimal use of irrigation can be characterised as the supply of sufficient water according to plant needs in the rooting area, and at the same time, avoiding the leaching of nutrients into deeper soil levels (Kru. ger et al., 1999). High frequency water management by drip irrigation minimises soil as a storage reservoir for water, provides at least daily requirements of water to a portion of the root zone of each plant, and maintains a high soil matric 237
# 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd
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potential in the rhizosphere to reduce plant water stress. On the other hand, the intensity of the operation requires that the water supply is kept at the optimum to maximise returns to the farmer. A widely adopted method for estimating crop consumptive water use (CWU) is the evaporation pan method, which relates evaporation from a Class A evaporation pan to CWU. These two quantities are related by what is called the crop coefficient K. Irrigation scheduling based on the crop coefficient K is one of the simplest methods where no sophisticated instrument is required. Precise values for K are often difficult to establish, given regional and site-specific, soil characteristics, crop physiology, and cultural practices. Any recommended value of K for a regional irrigation scheduling programme must be high enough to prevent water stress arising from emergencies and specialised local situations, while remaining low enough for efficient water management. Based on the US Weather Service Class A pan evaporation, many studies have been completed on the irrigation of broccoli, carrot, rape, and cabbage (Imtiyaz et al., 2000), cucumber (Eliades, 1988; Randall & Locascio, 1988), tomato (Locascio & Smajstrla, 1996) and potato (Ferreira & Carr, 2002; Panigrahi et al., 2001). The standard 200 mm diameter pan is a common instrument used to observe the water surface evaporation in China (Yuan et al., 2001) and in Japan (Yuan et al., 2003) and is equivalent to the US Weather Service Class A pan. Therefore, applying water by drip irrigation in relation to the amount of water evaporated from a standard 200 mm diameter pan would be also a convenient method to schedule irrigation, as standard 200 mm diameter pan evaporation data are relatively easy to obtain, though good pan evaporation data require careful measurements and frequent maintenance. The objectives of this study were: (1) to find the effects of water application amount during drip irrigation on strawberry growth and yield; (2) to find relationship between the water requirements of strawberry and a standard 200 mm diameter pan evaporation; and (3) to find the optimum value of crop coefficient K for drip irrigation scheduling of strawberry under controlled conditions.
2. Material and methods The experiment was conducted inside one plastic greenhouse at the farm of Yamaguchi University (latitude 348090 N, longitude 1318270 E and altitude 20 m above sea level) from November 2000 to June 2001. The plastic greenhouse was made of a steel frame
and covered by 01 mm thick white clear polyethylene (PE) film. The climate is warm temperate, humid marine in this area. On 18 November 2000, the strawberry (Fragaria ananassa Duch. Sachinoka) were planted inside the greenhouse. The soil type is silt loam, soil bulk density for 0–01 m depth is 1150 kg m3 and for 01– 02 m depth is 1220 kg m3, and soil pH value is 64. Fertiliser was applied uniformly to each treatment when the soil was ploughed. Plants were set 03 m apart in rows with a distance of 10 m between each row. After planting, overhead irrigation was used until the plants were established using the drip tube. The strawberry was covered with 003 mm thick black polyethylene mulch, and the water irrigated by the drip tube under the mulch. There are three treatments, denoted Ep075, Ep100 and Ep125, where the water quantities applied were 075, 100 and 125 times the pan evaporation measured by a standard 200 mm diameter evaporation pan placed above the plant canopy in the centre of the greenhouse. Fresh water (pH value of 72) was applied using the drip tube with emitters 22 mm apart placed 50 mm from the plant along the row under the mulch. The amount of irrigation water in mm was based on the area of the 1 m long by 05 m wide and the strawberry crop was irrigated every 2 days. Water was poured into storage tanks (20 l ) after measuring using catch cans. The tanks were connected to drip tubes, and were covered by the polyethylene plastic bags to prevent dust contamination. Plant protection was carried out as usual for this crop. Foliar and fruit diseases were controlled with timely sprays of agricultural chemical medicine. Tensiometers (DIK, Daiki Rika Kogyo Co. Ltd.) were located between two plants in a row; with the ceramic tip 02 and 04 m below the surface in the middle of the main rooting area of the strawberries (Albregts et al., 1996; Hochmuth et al., 1996; Kru. ger et al., 1999; Sav!e et al., 1993). Tensiometers readings were recorded daily at 08:00 h in the morning. Daily air temperatures and soil temperature were measured with mercury-inglass thermometers inside the greenhouse and Weather Station approximately 100 m from experimental field every day at 08:00 and 14:00 h. The evaporation inside greenhouse was measured with a standard 200 mm diameter evaporation pan. Plants were evaluated by the number of leaves and the number of flowers (including the fruits) every week. These measurements were made so that the relative growth could be determined for plants receiving different amounts of irrigation water based on the small pan evaporation. Runners and older leaves were removed by hand and dried as they developed throughout the growing seasons. After the last harvest, plants were removed, cleaned, and dried for tissue dry-weight
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3. Results and discussion 3.1. Weather conditions Without the heating systems, solar radiation is the only energy source inside the greenhouse. Solar radiation contributes to heating greenhouse in the day, and its contribution to the total heating requirement increases if the temperature is allowed to rise in the day and fall in the night. The air temperature inside the plastic greenhouse fluctuated substantially, as well as that of the solar radiation, because the solar radiation contributes to heating a greenhouse in the day. So, the greenhouse environment conditions differed from month to month. Air temperatures and soil temperatures at 01 m depth at 08:00 and 14:00 h inside and outside greenhouse are given in Fig. 1. From December 2000 to May 2001, the average air temperature at 08:00 h for each month inside greenhouse was 24, 18, 44, 77, 124 and 1018C higher than that outside the greenhouse. From January to May, the average soil temperatures (01 m depth) at 08:00 h for each month inside greenhouse were 64, 67, 69, 64 and 398C higher than that outside the greenhouse.
40 35 30 25 20 15 10 5 0 -5 12F 12S12L 1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
Calendar period
(a) 30 Soil temperature,˚C
determinations at 858C for 48 h to measure dry matter. Then, plant biomass was calculated. Mature strawberry fruits (at least 75% red colour) were harvested twice weekly and separated into four categories for berry fruit size: >15 g, >10 g, >5 g and 55 g to determine marketable, cull, and number and weight of berry fruit on each picking date. Marketable fruits were those fruit free of rot, well-shaped (conical or flat-wedge), and weighing 5 g or more. Fruit from each harvest in each grade category were conducted and weighed. Mean fruit weight was determined by weighing each fruit on each picking date and calculated as an average fruit weight. All components and marketable yield were analysed per plant. The irrigation water use efficiency (IWUE) for plant biomass is calculated as plant dry matter divided by the total amount of irrigation water; the irrigation water use efficiency (IWUE) for strawberry yield is calculated as the production of total fresh berry yield divided by the total amount of irrigation water. Statistical analysis was by standard analysis of variance (ANOVA). The treatments were run as a single-factor ANOVA. Where appropriate, single-degree-of-freedom orthogonal polynomial contrasts were used to determine whether differences existed between certain comparisons. The probability level for determination of significance was 005.
Air temperature,˚C
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25 20 15 10 5 0 12L 1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
(b)
Calendar period
Fig. 1. Comparison of air temperature (a) and soil temperature at 01 m depth (b) inside and outside a plastic greenhouse at 08:00 and 14:00 h from December 2000 to June 2001: F, S and L are the first, second and last ten days for every month; &, inside at 08:00 h; , inside at 14:00 h; }, outside at 08:00 h; n, outside at 14:00 h
Air temperatures were monitored three times on clear days during plant growth stages. Figure 2 shows the diurnal changes of air temperature and soil temperature at 01 m depth inside and outside a greenhouse. On clear days, diurnal changes of air temperature show a steep increase in temperature after sunrise, maximum values near 14:00 h, then followed by a steep decrease with low values before the sunset. The diurnal changes in soil temperature were later than those of air temperature inside and outside greenhouse. 3.2. Water applied and water used Inside a plastic greenhouse, irrigation water is the only source of moisture to the plants and there is no rainfall and no runoff using the drip irrigation systems. If the deep percolation and changes of soil water storage before and after the experiment are not considered, evapotranspiration of the strawberries is equal to the applied irrigation water. During the experimental period, the cumulative amount of irrigation water is equal to the fractions of the cumulative pan evaporation that is affected by air temperature (Fig. 3).
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45 40 35 30 25 20 15 10 5 0 -5 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 1618 20 22 Time, h
(a)
Soil temperature,˚C
30 25 20 15 10
3.3. Soil moisture tension
5 0
(b)
8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 1618 20 22 Time, h
Fig. 2. Diurnal changes of air temperature (a) and soil temperature at 01 m depth (b) inside and outside a greenhouse on clear days: }, outside on 17–18 January; &, inside on 17–18 January; n, outside on 26–27 March; , inside on 26–27 March; *, outside on 12–13 May; +, inside on 12–13 May
450 400 350 Amount of irrigation water, mm
During the growth period from 4 December 2000 to 20 June 2001, the cumulative irrigation water amounts were 2548, 3363 and 4140 mm, and the averages of irrigation water use were 13, 17 and 21 mm day1 for Ep075, Ep100 and Ep125, respectively. From Fig. 3, the strawberry growth inside greenhouse can also be divided into two stages by the amount of irrigation water. One is the period from 4 December 2000 to 20 March 2001; the amount of irrigation water is less and the averages of irrigation water use are 061, 078 and 092 mm day1 for Ep075, Ep100 and Ep125, respectively. Another period is from 21 March 2001 to 20 June 2001; the amounts of irrigation water are more and the averages of irrigation water use are 206, 275 and 343 mm day1 for Ep075, Ep100 and Ep125, respectively.
300 250 200 150 100 50 0 4/12 25/12 15/1 5 /2 26/2 19/3 9 /4 30/4 21/5 11/6 Date
Fig. 3. Cumulative amount of irrigation water based on the fraction of pan evaporation inside a greenhouse from 4 December 2000 to 20 June 2001: }, Ep075, 075 times pan evaporation; }, Ep100, 100 times pan evaporation; , Ep125, 125 times pan evaporation
From December 2000 to February 2001, the soil moisture tension at 02 and 04 m soil depth were similar for different treatments, about 5–10 kPa (Fig. 4). On reaching March, the air temperature became higher, plants grew faster and needed much soil water, and then, the applied irrigation water was insufficient to maintain the previous soil water tension. So, the soil moisture tension increased higher. From March to May, there was only the Ep075 treatment and at 02 m depth the soil moisture tension significantly changed from 65 to 43 kPa, while the soil moisture tension at 04 m depth had been over 70 kPa before the end of the May. However, the soil moisture tension of the Ep100 and Ep125 at 02 m depth only varied from 5 to 17 kPa; the soil moisture tension at 04 m depth varied from 5 to 23 kPa. During June, soil moisture tensions for three regimes at 02 m depth and 04 m depth all changed markedly and over 30 kPa. Soil moisture required by the strawberry plant in the earlier 3 months from December 2000 to February 2001 was low and soil moisture tension indicated that the soil water levels remained high from December 2000 to February 2001. Comparing the soil moisture tensions at 02 m depth [Fig. 4(a)] and 04 m depth [Fig. 4(b)] based on tensiometer values, it can be found that the changes in soil moisture tension at 02 and 04 m depth are similar, but the soil moisture tension at 04 m depth tended to be higher than at 02 m depth. So, the deep percolation and changes of soil water storage were neglected and not considered in the study. During the experimental period from December 2000 to May 2001, soil moisture tension of the Ep075 treatment significantly changed from 65 to 43 kPa, but the soil moisture tension of the Ep100 and Ep125
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Number of cumulative leaves per plant
100
80 70 60 50 40 30 20 10 0 12S12L1F 1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S Calendar period (a)
Soil moisture tension at 0.4 m depth, kPa
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90 80 70 60 50 40 30 20 10
80 70 60 50
0 11/12 1/1 22/1 12/2 5/3 26/3 16/4 7/5 28/5 18/6 Date
40 30 20 10 0 12S12L1F1S 1L 2F 2S 2L 3F 3S 3L 4F 4S 4L 5F 5S 5L 6F 6S
(b)
Calendar period
Fig. 4. Change in soil moisture tension at 02 m (a) and 04 m (b) depth for different treatments: F, S and L are the first, second and last ten days for every month; }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
varied from 5 to 17 kPa. In the literature, a value between 10 and 30 kPa is generally considered optimal for the growth of arable plants. In fertilisation trials on sandy soil, Hochmuth et al. (1996) used soil moisture tension between 5 and 15 kPa at 015 m depth to irrigate strawberry. Rennquist et al. (1982a, 1982b) obtained higher yield and bigger fruits in strawberries when the plants were grown at 10 to 50 kPa soil moisture tension at 02 m soil depth. Despite physiological and morphological adaptation to a water stress of 70 kPa, the strawberry cultivar ‘Chandler’ showed a higher yield when irrigation was applied to maintain a water potential of 10 kPa (Sav!e et al., 1993). 3.4. Plant development Figure 5 shows the dynamics of cumulative leaves per plant for different treatments every week from 11 December 2000 to 25 June 2001. At last, the cumulative
Fig. 5. Cumulative number of leaves per plant for different treatments from 11 December 2000 to 25 June 2001: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
number of leaves per plant for various treatments was 79, 89 and 94 for Ep075, Ep100 and Ep125, respectively. They were significant at the 005 level. The more amounts of irrigation water plot produced plants with more and vigorous leaves development. After regression analysis, they all expressed exponential growth (coefficient determination R2 > 098). Figure 6 shows the dynamic growth of flowers and berries per plant for different treatments every week from 11 December 2000 to 7 June 2001. The number of flowers and berries increased with plant growth and reached a maximum on 1 April. From April to the end of harvest, the number of flowers and berries of Ep125 and Ep100 were more than that of Ep075. That is to say, the greater amounts of irrigation water plot produced plants with more flowers and berries. During the plant growth stage, the older leaves and the new stems (new runners) were removed several times by hand, and dried for tissue dry matter determinations at 858C for 48 h. After the last harvest, plants were removed, cleaned, and also dried for tissue dry matter determinations at 858C for 48 h. Then, plant biomass was calculated. Figure 7 shows the cumulative aboveground (stems and leaves) biomass per plant. As for the leaves and flowers, the cumulative above-ground biomass has similar trends, the greater amounts irrigation water produced plants with more above-ground biomass, namely, 828, 929 and 1027 g per plant for Ep075, Ep100 and Ep125, respectively, and the
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30
affected the number of new runners, and the plots that received more irrigation water produced more new runners per plant (P ¼ 006).
25
3.5. Fruiting response
20 15 10 5 0 11/12 1/1
22/1
12/2
5/3 26/3 Date
16/4
7/5
28/5
Fig. 6. Number of flowers and berries per plant for different treatments from 11 December 2000 to 25 June 2001: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
130 120 Cumulative biomass per plant, g
110
a
100 90
a b
80
Crop yield is the most effective method of assessing economic benefits of production systems. The objective of planting any crop is to get the highest yield and the highest quality. In our experiment, strawberry harvesting stage was about 120 days from 25 February to 20 June. Figure 8 shows the dynamic changes in cumulated strawberry fruit yield per plant. There was a significant increase in total berry production as the amount of irrigation water increased from Ep075, Ep100 to Ep125. By April, air temperature was higher, plants grew faster; plant leaves, flowers and fruits increased more, and the strawberry yield also increased at the same time. From beginning to the end of the harvest, the peak harvest period was in April and May. There was neither an advance nor an elongation of the harvest period based on different treatments. For the applied irrigation water based on the pan evaporation, the total berry yield, >15 g and >5 g berry yield per plant for the treatment Ep100, are close to the treatment Ep125, and they are significantly larger than that of the treatment Ep075. The berry yield for 55 g are same for three different treatments. The maximum number of berries per plant was from Ep100, not from Ep125. Owing to the different number of berries
70 600
60 50
500
40 30 20 10 0
Ep0.75
Ep1.00 Treatment
Ep1.25
Fig. 7. Cumulative biomass (stems and leaves) per plant for different treatments: treatments Ep075, Ep100 and Ep125 denote applied irrigation water of 075, 100 and 125 times pan evaporation. Bars show the standard deviations for different treatments; letters a and b show the difference for treatment at 005 probability
Cumulative berry yield per plant, g
Number of flowers and berries per plant
35
400
300
200
100 0 20/2
differences were significant at the 005 level (probability P ¼ 004). The number of cumulative new runners was 356, 411 and 504 per plant for Ep075, Ep100 and Ep125, respectively. Different amounts of irrigation water
6/3
20/3
3/4
17/4 1/5 Date
15/5 29/5 12/6
Fig. 8. Cumulative berry yield per plant for different treatments from 20 February to 15 June: }, Ep075, 075 times pan evaporation; &, Ep100, 100 times pan evaporation; n, Ep125, 125 times pan evaporation
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Table 1 The strawberry yields per plant in g, number of berries per plant and average berry weight in g for different treatments; the treatment of Ep0.75, Ep1.00 and Ep1.25 are applied irrigation water as 0.75, 1.00 and 1.25 times pan evaporation, respectively; Av. berry weight is average berry weight per plant Treatment
Berry yield per plant, g Total
Ep075 Ep100 Ep125
b
4168 5201a 5453a
>15 g
>10 g
1270 1516 1914
b
2338 3032a 3397a
Berry number
>5 g
55 g
b
3668 4643a 4901a
Total
500 558 547
Av. berry weight, g
>5 g b
513 629 595
340 451a 427a
Total
>5 g
79 80 86
104 105 112
Note: Where significant irrigation effects were detected by the analysis of various, column means followed by the same letter are not significantly different at the 005 probability level.
600
550 Berry yield per plant, g
per plant and the large variance in fruit weights throughout the harvest period, there was no significant difference in mean fruit weight based on the total numbers (Table 1). From Fig. 8 and Table 1, it can be found that the dynamic changes in accumulated strawberry yield and the total berry yield per plant are affected by the different amounts of irrigation water. Greater the amount of irrigation water, the larger the berry yield. The increase in the amount of irrigation water also produced larger berry weight. Irrigated water increased strawberry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. In general, irrigation increased total season fruit yields, marketable yields and the number of berries, which is in good agreement with the literature (Rennquist et al. 1982a, 1982b; Sav!e et al., 1993; Kru. ger et al., 1999).
500
450
400
350
300 200
250
300 350 400 450 Applied irrigation water, mm Fig. 9. Relationship between total amount of applied irrigation water and the total fresh strawberry yield
3.6. Production function and irrigation water use efficiency In the experiment, there were various production functions concerned with the total amount of applied irrigation water relative to berry yield components. Here, the production function selected was the total amount of applied irrigation water in terms of fresh berry yield in g per plant. Figure 9 shows the relationship between the total amount of applied irrigation water and total fresh berry yield. Through non-linear regression analysis, a mathematical function was obtained: y ¼ 00081x2 þ 62036x 62599
ð1Þ
where: y is strawberry yield per plant in g; and x is applied irrigation water in mm. The crop coefficient K is irrigation water related to the evaporation from a standard 200 mm diameter evaporation pan. Based on the above mathematical function, the optimal amount of irrigation water for the maximum berry yield is about 380 mm and the optimum value of
crop coefficient K is about 11 for drip irrigation of strawberry inside a plastic greenhouse. Irrigation water use efficiency (IWUE) is the relation between yield or dry matter produced and the quantity of irrigation water. Figure 10 shows IWUE in terms of expressed total fresh berry yields and IWUE in terms of expressed dry plant biomass for each treatment. The IWUE related to the production of total fresh berry yields were 169, 163 and 136 g mm1 for Ep075, Ep100 and Ep125 regimes, respectively. The IWUE related to the plant biomass were 033, 028 and 025 g mm1 for the Ep075, Ep100 and Ep125 regimes, respectively. In general, the trends for both the IWUE for plant biomass and IWUE for the production of total fresh berry yields showed that the lower the amount of irrigation water received, higher the irrigation water use efficiency within the threshold of applied irrigation water. Considering the strawberry yield and IWUE for strawberry yield, IWUE of treatment Ep100 is optimal,
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during the full growth seasons. The use of a lower pan factor may reduce the berry yield significantly.
0.4 0.3
2.0
0.3 1.5
0.2 0.2
1.0
0.1 0.5
IWUE for plant biomass, g mm-1
IWUE for berry yield, g mm-1
2.5
0.1 0.0
Ep0.75
Ep1.00 Treatment
Ep1.25
Acknowledgements This work was supported by a grant from Ministry of Education, Culture, Sports, Science and Technology through the Japanese Government Scholarship (Japan). The authors would like to thank Professor Yaohu Kang, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, China, for his suggestions on the paper. We are also grateful to the reviewers for perceptive comments and corrections.
0.0
Fig. 10. Irrigation water use efficiency (IWUE) related to the plant biomass and the production of total strawberry yield: treatments Ep075, Ep100 and Ep125 denote applied irrigation water of 075, 100 and 125 times pan evaporation: &, irrigation water use efficiency for plant biomass; n, irrigation water use efficiency for berry yield
and the IWUE for strawberry yield production is about 163 g mm1 inside a plastic greenhouse.
4. Conclusion In the drip irrigation experiment inside plastic greenhouse, effects of different irrigation water based on the pan evaporation inside greenhouse on the strawberry growth and yield were studied. Plant leaves, flowers and fruits, above-ground biomass, runners, total berry yields, marketable berry yields (>5 g), the size of strawberry fruits all increased with the amount of irrigation water increasing, from Ep075, Ep100 to Ep125. Irrigated water increased berry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. The trends of the irrigation water use efficiency showed that the lower the amount of irrigation water received, the higher the irrigation water use efficiency obtained for the drier plant biomass and berry yields. The optimal amount of irrigation water is about 380 mm and the optimal pan factor is about 11 for strawberry growth inside plastic greenhouse. Applying water by drip irrigation in relation to the amount of water evaporated from a standard 200 mm diameter pan is a convenient, simple, easy and low cost method. Therefore, strawberries grown inside plastic greenhouse should be irrigated using a pan factor of 11 as a guideline for irrigation
References Albregts E E; Clark G A; Stanley C D; Zazueta F S; Smajstrla A G (1991). Preplant fertilization of fruiting microirrigated strawberry. HortScience, 26(9), 1176–1177 Albregts E E; Hochmuth G J; Chandler C K; Cornell J; Harrison J (1996). Potassium fertigation requirements of drip-irrigated strawberry. Journal of the American Society for Horticultural Science, 121(1), 164–168 Baumann T E; Eaton G W; Spaner D (1993). Yield components of day-neutral and short-day strawberry varieties on raised beds in British Columbia. HortScience, 28(9), 891–894 Blatt C R (1984). Irrigation, mulch, and double row planting related to fruit size and yield of ‘Bounty’ strawberry. HortScience, 19(6), 826–827 Dwyer L M; Stewart D W; Houwing L; Balchin D (1987). Response of strawberry to irrigation scheduling. HortScience, 22(1), 42–44 Eliades G (1988). Irrigation of greenhouse-grown cucumbers. Journal of Horticultural Science, 63(2), 235–239 Ferreira T C; Carr M K V (2002). Responses of potatoes (Solanum tuberosum L.) to irrigation and nitrogen in a hot, dry climate. I. Water use. Field Crops Research, 78, 51–64 Goulart B L; Funt R C (1986). Influence of raised beds and plant spacing on growth and yield of strawberry. Journal of the American Society for Horticultural Science, 111(1), 176–181 Haraguchi T; Nakano Y; Kuroda M; Hirota O (2000). Evapotranspiration in a platic greenhouse with side-openings. Transaction of the Japanese Society of Irrigation, Drainage and Reclamation Engineering, 209, 35–41 Hochmuth G J; Albregts E E; Chandler C C; Cornell J; Harrison J (1996). Nitrogen fertigation requirements of drip-irrigated strawberry. Journal of the American Society for Horticultural Science, 121(4), 660–665 Imtiyaz M; Mgadla N P; Manase S K; Chendo K; Mothobi E O (2000). Yield and economic return of vegetable crops under variable irrigation. Irrigation Science, 19(2), 87–93 Kasperbauer M J (2000). Strawberry yield over red versus black plastic mulch. Crop Science, 40(1), 171–174 Kr.uger E; Schmidt G; Bruckner U (1999). Scheduling strawberry irrigation based upon tensiometer measurement and a climatic water balance model. Scientia Horticulturae, 81, 409–424
ARTICLE IN PRESS EFFECT OF DRIP IRRIGATION ON STRAWBERRY
Locascio S J; Smajstrla A G (1996). Water application scheduling by pan evaporation for drip-irrigated tomato. Journal of the American Society for Horticultural Science, 121(1), 63–68 Panigrahi B; Panda S N; Raghuwanshi N S (2001). Potato water use and yield under furrow irrigation. Irrigation Science, 20, 155–163 Randall H C; Locascio S J (1988). Root growth and water status of trickle-irrigated cucumber and tomato. Journal of the American Society for Horticultural Science, 113(6), 830–835 Rennquist R P; Breen J; Martin L W (1982a). Vegetative growth response of ‘Olympus’ strawberry to polyethylene much and drip irrigation regimes. Journal of the American Society for Horticultural Science, 107, 369–372
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Rennquist R P; Breen J; Martin L W (1982b). Effect of polyethylene much and summer irrigation on subsequent flowering and fruiting of ‘Olympus’ strawberry. Journal of the American Society for Horticultural Science, 107, 373–376 Sav!e R; Pe*nuelas J; Marf"a O; Serrano L (1993). Changes in leaf osmotic and elastic properties and canopy structure of strawberry under mild water stress. HortScience, 28(9), 925–927 Yuan B Z, Kang Y; Nishiyama S (2001). Drip irrigation scheduling for tomatoes in unheated greenhouse. Irrigation Science, 20, 149–154 Yuan B Z, Nishiyama S; Kang Y (2003). Effects of different irrigation regimes on the growth and yield of dripirrigated potato. Agricultural Water Management, 63(3), 153–167.