Water use and yield relationships of irrigated potato

Agricultural Water Management, 18 ( 1 9 9 0 ) 173-179

173

Elsevier Science Publishers B.V., A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s

Water use and yield relationships of irrigated potato Talebul Islam, Habibullah Sarker, Jahangir Alam and Harun-Ur-Rashid Bangladesh Agricultural Research Institute, Joydebpur (Bangladesh) (Accepted 3 October 1989 )

ABSTRACT Islam, T., Sarker, H., Alam, J. and Harun-ur-Rashid, M. 1990. Water use and yield relationships of irrigated potato. Agric. Water Manage., 18:173-179. The experiment was conducted at Joydebpur, Bangladesh, during the rabi (dry) seasons of 19861987 and 1987-1988 with potato cultivar "Cardinal". Four treatments: no irrigation, irrigation at 80%, 60% and 40% depletion of available soil moisture (ASM) were tested. For both the years five irrigations given at 40% depletion Of ASM gave maximum yield (22.3 t ha J ) which was significantly different from the other treatments. On average 40 m m water was applied at an interval of around 12 days starling from 30 days after planting. The same treatments resulted in maximum number of stems per hill, highest foliage coverage and maximum number of compound leaves; maximum weight and number of tubers as percentage of total yield in the range of 28-45 m m and > 45 mm in size. It also resulted in maximum overall water use efficiency of 81.0 kg ha ~ m m -~, irrigation water use efficiency of 79.5 kg h a - ~ m m - ~ and a maximum total water use of 267 mm. The average daily evapotranspiration varied from 1.0-5.1 mm. The non-irrigated treatment gave the highest percentage of tubers smaller then 28 mm.

INTRODUCTION

Potato is one of the main cash crops and most important vegetables in Bangladesh. Being a shallow rooted crop and cultivated during the dry season, it needs frequent irrigation for good growth and yield. For national water planning, institutional project planning and planning at farm level, knowledge of the water requirement of potato is essential. To irrigate adequately and efficiently, appropriate irrigation scheduling for the crop is required. Haverkort (1982) found that a good potato crop requires 400 to 800 mm of water during the growing season. Dimitrov's ( 1983 ) findings reveal that for a better yield potato uses from 380 to 450 mm of water. Karim et al. (1982) reported that the seasonal water requirement of potato under the agroclimatic conditions of Joydebpur is 284 mm, whereas Khan et al. ( 1981 ) found it to be 432 mm. Karim et al. ( 1982 ) found a maximum yield with six irrigations, but Khan et al. ( 1981 ) recommend eight irrigations for a maximum yield. 0378-3774/90/$03.50

© 1990 Elsevier Science Publishers B.V.

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Further conformation of these results and some specific recommendations would be valuable for researchers as well as for farmers and planners. This experiment was conducted with the objectives to determine the water requirement of potato and to identify the yield response of the crop to different irrigation regimes. MATERIALS A N D M E T H O D S

The experiment was conducted during the rabi (dry) seasons of the years 1986-1987 and 1987-1988 at the central farm of Bangladesh Agricultural Research Institute at Joydebpur with the treatments: no irrigation (To), irrigation at 80% depletion of available soil moisture, ASM (T,), at 60% (T2) and at 40% depletion ( T 3 ) . After the first year of our study some sand was added to the silty clayloam soil of the experimental field to improve its texture. The bulk density, field capacity and wilting percentage (average for the two years) were 1.48 g cm -3, 37 vol% and 19 vol%, respectively. A randomized complete block design with four replications was used to compare the treatments. Polyethylene sheet to a depth of 0.4 m was used around the 4.5)< 3.6 m 2 plots to prevent lateral seepage. The gravimetric method was used to determine the soil moisture content. Soil samplings for moisture content were done at 7 day intervals and also before and after each irrigation. Fertilizer doze was Nl60PlooKlso kg ha-~. Potatos of the Cardinal variety were planted with a spacing of 30 cm and 60 cm row to row distance. Data on the number of stems per hill, foliage coverage and number of compound leaves per plant were taken on the 60th day after planting. The tubers were graded into 3 size ranges: < 28 mm, 28-45 m m and > 45 m m as used in the Potato Research Centre of Bangladesh Agricultural Research Institute.

RESULTS A N D D I S C U S S I O N

Irrigation requirement and water use Table 1 lists the parameters for irrigation and water use of potato. During both the years, T 3 required the largest of irrigations and used the maximum amount of water both for irrigation and as total seasonal use. In 1986-1987 the daily average evapotranspiration for treatments T 3 w a s found to vary from 1.0 to 5.1 m m d a y - 1 with the maximum during the last ten days of January. For treatments TI and Te it varied from 1.0 to 4.6 m m d a y - 1 with the same period of peak use (Fig. 1 ). The total seasonal water use in 1987-1988 was relatively less than that in the previous year, which was contributed by rainfall as well (Fig. 2 ). The daily average of evapotranspiration during this year

WATER USE-YIELD RELATIONSHIP OF IRRIGATED POTATO

175

TABLE 1 Irrigation parameters and water use of potato Year

Treatment

Total water

use

Irrigation number

Depth of irrigation

Irrigation applied on

(mm)

DAP a

1 2 3 1 2 3 4 1 2 3 4 5

69 77 72 45 58 61 58 37 52 54 56 51

40 61 83 35 50 66 82 30 42 56 70 79

1 2 3 1 2 3 1 2 3 4 5

47 44 49 41 40 42 30 35 32 35 31

48 69 86 45 63 79 39 50 63 73 82

(mm) 1986-1987

1987-1988

To Ti

68 263

T2

270

T3

293

To Tl

112 203

T2

200

T3

241

aDAP: Days after planting.

was lower than the previous year, which varied from 1.0 to 4.5 m m d a y - l for treatment T3 (Fig. 1 ). The period of peak evapotranspiration in this year was the same as in the previous year. The total seasonal water use and the daily average evapotranspiration in 1986-1987 was higher than in 1987-1988. This may be due to the higher temperature (Fig. 2 ). Khan et al. ( 1981 ) found the total seasonal water use for potato irrigated at 10 day intervals to be 432 m m at Joydebpur, which is substantially higher than was found in the present work (Table 1 ). However, Karim et al. ( 1 9 8 2 ) found it to be 284 m m through field experiments and 275 m m by using empirical methods for the same region, which are very close to our findings. Khan et al. ( 1981 ) found m a x i m u m yield with 6 irrigations at 12 day intervals at Joydebpur, whereas we got it with 5 irrigations.

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Fig. 1. Daily water use of potato as an average of 10 days. ( • ) T l; ( O ) T2, (/k ) T3; and ( ~ ) TI,2,3.

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WATER USE-YIELD RELATIONSHIP OF IRRIGATED POTATO

177

Tuber yield and its components Agronomical parameters and yield for both the years and their average are given in Table 2. Treatments T 3 gave the highest yield, the m a x i m u m number of stems per hill, the highest number of c o m p o u n d leaves per plant and the largest foliage coverage during 1986-1987. In the following year tuber yield and foliage coverage gave m a x i m u m values in treatment T 3 ; other parameters did not show any significant difference among the treatments. N u m b e r and weight of tubers in percentage of total yield with size ranges and affected by scab disease for 1987-1988 are listed in Table 3. Under nonirrigated condition the significantly lowest number of tubers were greater than 45 m m and the highest n u m b e r of tubers were smaller than 28 m m in size. Overall water use efficiency (WUE) and irrigation WUE for both the years and their average are given in Table 4. Treatment T 3 gave m a x i m u m efficiency for both the years and both the parameters with the exception for overall water use in 1987-1988, where T 1 gave m a x i m u m efficiency. The treatment irrigated at 40% depletion of available soil moisture ( T 3 ) gave the highest yields. It showed statistically insignificant difference from T2 in 1986-1987 (Table 2) and T1 i 1987-1988. Average values for both the years showed its significant difference from those two treatments. Differences between treatments T1 and T2 were insignificant for both the years as well as in their average values. The fourth irrigation to T 2 w a s not required in 19871987 and ultimately the total irrigation depth for T1 became higher than that TABLE 2 Influence o f irrigation on a g r o n o m i c a l p a r a m e t e r s a n d yield o f potato Year

Treatment

Number of s t e m s per hill

Foliage coverage (%)

Compound leaves per plant

T u b e r yield (t h a - ~)

1986-1987

To Ti

1.8 2.2 2.5 3.0

b* b ab a

22.8 52.0 60.2 71.5

c b b a

4.8 7.9 9.4 11.4

c b ab a

2.6 11.0 14.9 20.2

c b ab a

4.0 4.8 5.3 4.6

a a a a

55.0 70.0 71.3 82.5

b ab ab a

4.5 5.0 5.8 5.5

a a a a

8.5 20.5 17.5 23.0

c ab b a

4.7 6.1 7.6 9.1

d c b a

5.6 c 15.8b 16.2 b 22.3 a

T2 T3

1987-1988

To T~ T2 T3

Average

To T~ T2 T3

2.9 b 3.5ab 3.9 a 3.8 a

36.3 c 55.0b 58.8 b 68.8 a

*Values scored with the s a m e letter are n o t significant at P = 0.05.

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T. ISLAMET AL.

TABLE 3 Size grading and scab infection of potato tubers influenced by irrigation regimes in percentage of total yield (1987-1988)

Treatment

To T~ T2 T3

Tubers with diameter

Scab

> 45 m m

disease affected

28-45 m m

< 28 m m

Number

Weight

Number

Weight

Number

Weight

0.6b* 14.5a 10.9a 14.2a

2.0c 32.2b 26.6b 42.5a

62.9a 66.4a 67.3a 66.7a

82.8a 59.7a 64.1a 52.0a

36.4a 18.7b 21.4b 18.7b

15.2a 8.1 a 9.3a 5.5a

0.3a 0.4a 0.4a 0.4a

*Values scored with the same letter are not significant at P = 0.05. TABLE 4

Water use efficiency of potato under different irrigation regimes Year

1986-1987

Treatment

To TI T2 T3

1987-1988

To Tl T2 T3

Average

To Tl T2

T3

Overall WUEa

Irrigation WUE

( k g h a -~ m m - l )

(kgha -j mm -I)

44.1 41.9 55.3 69.0

36.7 54.1 68.0

80.4 101.0 85.5 95.4

85.7 73.2 85.9

66.7 69.0 67.6 81.0

60.4 58.4 79.5

aWUE: Water use efficiency.

for T2 (Table 2). This may be a reason for statistically insignificant higher yield (Table 2 ); the rainfall during the same year (Fig. 2 ), probably, a factor influencing T~ to give higher yield close to T 3 and consequently higher overall water use efficiency (Table 4 ). Higher WUE in 1987-1988 compared with the previous year may be related to the lower temperature, since the potato plants do not form tubers at temperature above 25 °C. Response of foliage coverage to different soil moisture regimes was significant (Table 2). higher foliage coverage is related to higher photosynthesis and consequently influenced the tuber yield. Results in Table 3 reveal that the

WATER USE-YIELD RELATIONSHIP OF IRRIGATED POTATO

179

soil moisture deficit under non-irrigated condition hampered the normal growth of the tubers and left highest percentage of tubers smaller than 28 m m in size. The differences among the treatments in percentage of scab-affected tubers (Table 3) were not significant. On the contrary, Ronsen et al. (1983) and Haverkort (1982) found irrigated potatoes to be less susceptible to scab disease.

REFERENCES Dimitrov, S., 1983. Evapotranspiration of late potatoes. Field Crop Abstr., 36(3): 252. Haverkort, J.A., 1982. Water management in potato production. Techn. Inf. Bull., 15. CIP, Lima, Peru. Khan, M.S., Karim, S., Short, K.E. and Karim, Z., 1981. The yield response of potato to varying quantitites of nitrogen and irrigation. Proc. 4th Workshop of Potato Research Workers, Bangladesh, pp. 47-53. Karim, Z., Khan, M.S., Karim, A.J.S. and Rahman, M., 1981-82. Study of soil and water management practices for crop production - potato. Second Ann. Rep., Coordinated Irrigation and Water Management Studies. Soils and Irrigation Div., BARC, Dhaka. Karim, Z., Khan, M.S. and Akand, N.A., 1982. Potential evapotranspiration, rainfall probability and irrigation requirement of potato for different agroclimatic regions of Bangladesh. Proc. 5th Workshop of Potato Research Workers, Bangladesh, pp. 96-19. Ronsen, K., Rognerud, B., Trandstat, T. and Enge, R., 1983. Quality production of the potato variety Maudelpoted. Field Crop Abstr., 30( 1 ): 80.