Productivity of greenhouse roses following changes in soil moisture and soil air regimes

Scientia Horticulturae, 2 (1974) 137--143 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

PRODUCTIVITY OF GREENHOUSE ROSES FOLLOWING CHANGES IN SOIL MOISTURE AND SOIL AIR REGIMES

Z. PLAUT and N. ZIESLIN* Institute Soils and Water, Agricultural Research Organization. The Volcani Center, Bet Dagan (Israel) * Faculty o f Agriculture, Hebrew University o f Jerusalem, Rehovot (Israel) Contribution 1973 Series, No. 282-E from the Volcani Center (Received October 29, 1973) ABSTRACT Plaut, Z. and Zieslin, N., 1974. Productivity of greenhouse roses following changes in soil moisture and soil air regimes. Scientia Hort., 2 : 137--143. Following 2 years of different soil moisture and air regimes for 'Baccara' roses, the optimal regimes were chosen and kept uniform for each growth medium. These regimes were implemented for an additional year (1971--1972). Soil moisture and soil air regimes employed in previous years (1969--1971) had significant after-effects on flower yields in 1971--1972, but no effect on flower quality or weight. The effect of previous suboptimal moisture and air regimes was apparently due to the number of main branches formed per plant in the initial two years, which was unaffected after implementation of optimal regimes. Approximately 4 weeks after cessation of cutting, the root system constituted 11--15% of the total weight of the plant. While 65% of the root system in non-separated beds was located in a soil layer between 30 and 60 cm, only 27% were located above this layer.

INTRODUCTION T h e i m p o r t a n c e o f f r e q u e n t w a t e r s u p p l y in o r d e r t o m a i n t a i n l o w soil w a t e r s u c t i o n is g e n e r a l l y a c c e p t e d f o r o r n a m e n t a l c r o p s ( S h i l l o a n d H a l e v y , 1964; Hanan, 1965; Holley and Goldsberry, 1968; Hanan and Jasper, 1969; White, 1970; Hanan, 1972). In a p r e v i o u s i n v e s t i g a t i o n w i t h roses, m a x i m u m f l o w e r p r o d u c t i o n was o b t a i n e d in a s a n d y - l o a m soil w h e n i r r i g a t e d f r e q u e n t l y e n o u g h so t h a t soil s u c t i o n n e v e r e x c e e d e d 5 c e n t i b a r s (cb) ( P l a u t et al., 1 9 7 3 ) . M a i n t a i n i n g w a t e r s u c t i o n c l o s e t o z e r o r e s u l t e d , h o w e v e r , in d e c r e a s e d p r o d u c t i o n w h e n d r a i n a g e was i n a d e q u a t e a n d r o o t s w e r e e x p o s e d t o a l o w air c o n t e n t . This i n v e s t i g a t i o n was e x t e n d e d t o s t u d y w h e t h e r s u b o p t i m a l soil m o i s t u r e a n d soil a i r r e g i m e s c o n t i n u e d t o d e t e r m i n e f l o w e r p r o d u c t i o n a f t e r o p t i m a l r e g i m e s w e r e e s t a b l i s h e d . T h e e f f e c t o f a l t e r a t i o n s in m o i s t u r e a n d air r e g i m e s o n t h e r o o t s y s t e m o f roses was also i n v e s t i g a t e d .

138 MATERIALS AND METHODS Roses cv. 'Baccara' were planted in February, 1969, in 4 different root media. Three of the media were placed in raised benches 30 cm deep, and contained (a) a coarse-textured sandy loam; (b) the identical sandy loam mixed 1:1 (v/v) with sphagnum peat moss; and (c) a vulcanic scoria (tuff). The fourth medium consisted of sandy loam as (a) in a 60-cm-deep bench non-separated from the local soil. In each of the sandy loam media four moisture regimes were established, in which water suction was allowed to rise to 5, 10, 20 or 50 cb. In the t u f f medium, irrigation was given at predetermined intervals of 1/s--1/4, 1/2, 1, and 2--3 days. The experimental l a y o u t as well as details about the irrigation and fertilization methods, determination of water and osmotic suctions and flower yields were described earlier (Plant et al., 1973). The different moisture and air regimes were maintained up to July, 1971, when uniform and optimal soil moisture and soil air regimes were implemented for each m e d i u m for an additional year. The selected regime for the nonseparated bench was the most frequent irrigation regime, which maintained a maximal water suction of 5 cb. For the raised benches, the regime which aUowe.d a rise in tension up to 10 cb was chosen, as this permitted better aeration and resulted in higher yields. The plants grown in t u f f were irrigated every 1/8--1/4 day. Fertilizer (1 g/1 of a 20--20--20 mixture) was applied to the sandy loam once every 7--10 days with a large dose of water. Between fertilizer applications, small quantities of water were applied to maintain the required suction. In the t u f f 2 fertilizations were applied daily. Number of flowers and their length and weight were recorded from November to May. The rose bushes were u p r o o t e d approximately 4 weeks after termination of cutting. The roots were removed in the raised benches to the very b o t t o m (30 cm) and in the non-raised beds to a depth of about 40 cm. R o o t samples were also taken in the non-separated beds to a depth of 90 cm to determine their distribution with depth. RESULTS AND DISCUSSION The contribution of suboptimal soil moisture or soil air regimes to flower yields after implementation of optimal regimes is of importance in determining a plant's adaptability to the new conditions. Knowledge of this ability will be of aid in estimating whether perennial plants like roses will recover in productivity after a period of environmental stress. Fig.1 shows t h a t maintaining optimal moisture and air regimes in the soil t h r o u g h o u t an entire year did n o t abolish previous effects of the different regimes. The m a x i m u m yield of 266 flowers/m 2 was obtained in the nonseparated beds where the soil water suction was the lowest t h r o u g h o u t the

139 300

I

I

I

I

20

I

I

I

I

l

I

2 0 0 --

,~ 1 0 0 - "

O

O

10

MAXIMAL

:E

i

300 l

30 WATER SUCTION MEDIA

40 50 IN G R O W T H

(bor~lO-2)

I

I

I

I

I b

200 -

~

- -

1 0 0 --

t

I

I

I

I

1

05 10 15 20 25 iNTERVAL BETWEEN IRRIGATIONS (days)

Fig.l.a. The effect of maximal water suction at a depth of 20 am in the sandy loam media during the years 1969--1971 on the flower yields in 1971--1972, following implementation of a uniform soil moisture regime under which maximal suction was 5 eentibar. (. = sandy loam, non separated; e (open circles) = sandy loam; • = sandy loam + peat moss, both separated). Fig.l.b. The effect of irrigation frequency in the tuff during the years 1969--1971 on the flower yield in 1971--1972, following implementation of a uniform frequency of 4--8 irrigations per day. t h r e e y e a r s o f the e x p e r i m e n t . In t h e raised b e n c h e s t h e w e t t e s t m o i s t u r e regime w h i c h caused i n s u f f i c i e n t air s u p p l y to the r o o t s y s t e m d u r i n g 1 9 6 9 - 1 9 7 1 (Plaut et al., 1 9 7 3 ) , as well as t h e d r y m o i s t u r e regime, decreased flowers y i e l d in 1 9 7 1 - - 1 9 7 2 , w h e n the m o i s t u r e regime was o p t i m a l i z e d . A l o w e r yield was o b s e r v e d in t h e beds w h i c h c o n t a i n e d p e a t c o m p a r e d w i t h s a n d y l o a m beds, p r o b a b l y d u e t o partial d e c o m p o s i t i o n w i t h time. T h e e f f e c t o f p r e v i o u s irrigation f r e q u e n c y can also be seen in t h e t u f f m e d i u m , m a i n l y f o r t h e p l o t s w h i c h were p r e v i o u s l y irrigated at t h e t w o l o w e r frequencies. The n u m b e r o f m a i n b r a n c h e s was n o t a f f e c t e d b y t h e i m p r o v e m e n t o f the m o i s t u r e regimes, a n d a r e m a r k a b l e d i f f e r e n c e in their n u m b e r r e m a i n e d even a f t e r a y e a r o f o p t i m a l m o i s t u r e regimes (Table I). T h e largest n u m b e r o f

140 TABLE I Number of main branches on rose plants (per m ~) at the end of a three-year experiment: 1969--1972 (counted in May 1972) Growth media

Sandy loam, non-separated Sandy loam raised Sandy loam + peat moss, raised

Maximal soil water suction in growth media during 1969--1971 (cb) 5

10

20

50

SE

32.0 21.1 15.0

30.0 23.0 22.1

29.5 20.4 16.7

26.5 18.2 15.9

1.8 1.0 1.1

Interval between irrigation (days)

Tuff

1/8--1/4

1/2

1

2--3

22.7

23.1

20.7

18.0

1.1

b r a n c h e s was f o u n d in t h e s a n d y l o a m n o n - s e p a r a t e d a n d in spite o f b e i n g r e d u c e d a t t h e higher w a t e r s u c t i o n s , t h e n u m b e r e x c e e d e d t h a t in t h e raised b e n c h e s . In t h e s a n d y l o a m raised b e n c h e s t h e m a x i m u m n u m b e r o f b r a n c h e s was f o u n d w h e n an i n t e r m e d i a t e m o i s t u r e r e g i m e was a p p l i e d f o r t h e p r e v i o u s t w o years. In t h e t u f f a significant decline in n u m b e r o f b r a n c h e s was observed o n l y a t t h e driest m o i s t u r e regime. A c o m p a r i s o n b e t w e e n Fig.1 a n d T a b l e I implies t h a t t h e n u m b e r o f f l o w e r s p r o d u c e d p e r m a i n b r a n c h was h i g h e r in t h e t u f f t h a n in t h e raised b e n c h e s c o n t a i n i n g soil. This w o u l d indic a t e t h a t in t h e t u f f m e d i u m e i t h e r m o r e g r o w i n g p o i n t s w e r e active p e r b r a n c h , or t h a t t h e r a t e o f f l o w e r d e v e l o p m e n t was i n c r e a s e d (Zieslin et al., 1973). F l o w e r q u a l i t y was e v a l u a t e d b y division i n t o t h r e e g r o u p s a c c o r d i n g t o length; a b o v e 70 c m , 5 0 - - 7 0 c m , a n d b e l o w 50 c m . T h e d i s t r i b u t i o n o f flowers a m o n g t h e s e g r o u p s was u n a f f e c t e d b y p r e v i o u s irrigation r e g i m e s a f t e r a u n i f o r m m o i s t u r e r e g i m e was e s t a b l i s h e d (Fig.2). T h e g r o w t h m e d i a h a d , h o w ever, a significant e f f e c t o n s t e m length. In t h e raised b e n c h e s c o n t a i n i n g s a n d y l o a m t h e p e r c e n t a g e o f t h e b e t t e r f l o w e r grades was f o u n d t o be l o w e r t h a n in t h e t u f f or in t h e n o n - s e p a r a t e d b e n c h . T h e average w e i g h t o f flowers, w h i c h is also an e v a l u a t i o n o f t h e i r q u a l i t y , is p r e s e n t e d in T a b l e II. I t is e v i d e n t t h a t m o i s t u r e r e g i m e s o f p r e v i o u s y e a r s h a r d l y a f f e c t e d average f l o w e r weight, while g r o w t h m e d i a h a d a similar e f f e c t o n w e i g h t as o n s t e m length. This suggests t h a t t h e d e v e l o p m e n t a n d final size o f an individual f l o w e r are in essence f u n c t i o n s o f c o n d i t i o n s prevailing d u r i n g its g r o w i n g p e r i o d , w h e r e a s t h e n u m b e r o f flowers p r o d u c e d , also d e p e n d s o n t h e s t a t u s o f t h e r o s e b u s h a n d its p r e v i o u s g r o w t h c o n d i t i o n s . T a b l e I I I p r e s e n t s r o o t fresh w e i g h t s at t h e e n d o f t h e e x p e r i m e n t . I t s h o u l d b e n o t i c e d t h a t o n l y in t h e raised b e n c h e s w e r e m o s t o f t h e r o o t s retrieved, w h e r e a s in t h e n o n s e p a r a t e d b e d s s o m e r e m a i n e d in t h e d e e p soil layers.

141 <

?

100

SANDY LOAM

Non.se ~arated

Peat separated

Separated

Tuff

7I

w

b z o

50

F-

S

I I0 20 50 5 10 20 50 5 10 20 50 MAXIMAL WATER SUCTION IN GROWTH MEDIA ( bar x10"2)

0.15 05 10 2.5 DAYS BETWEEN IRRI GATIONS

J

Stern tength (cm) r--7

<50

ITnll

50-70 >To

Fig.2. The effect of maximal water suction at a depth of 20 cm in the sandy loam media and of irrigation frequency in the tuff m e d i u m during the years 1969--1971, on the distribution of flowers according to length in 1971--1972, following implementation o f a uniform moisture and air regimes (see Fig.l). TABLE II Average flower weight (g) which were cut from November 1971 to May 1972 Growth media

Sandy loam, non-separated Sandy loam, raised Sandy loam + peat moss, raised

Maximal soil water suction in growth media during 1969--1971 (centibars) 5

10

20

50

22.9 21.4 20.4

23.9 22.0 19.5

22.9 22.1 21.2

23.2 21.6 21.5

Interval between irrigation (days)

Tuff

118--114

1/2

1

3--2

24.0

25.5

24.7

23.6

Therefore, the low percentage of the root fresh weight out of the total plant weight is remarkably low mainly in the raised benches with sandy loam. A slight increase in relative root weights can be seen in the tuff and probably an additional increase in the non-separated beds which may be even higher if the deeper roots would be included. The moisture regimes during previous years had no apparent effect on the weight of the roots in any growth medium. An interesting phenomenon was the depth distribution of the roots in the non-

Tuff

Sandy loam, non separated Sandy loam, raised Sandy loam + peat moss, raised

Growth media

Root weight as % of total plant weight

14.3 11.8 13.0

943

838

817

13.0

717 559 414

5

896

669 510 463

50

1/8--1/4

713 621 633

714 541 496

20

Interval between irrigation (days) 1/8--1/4 112 1 2--3

10

5

13.8

112

15.1 12.1 13.0

10

14.7

1

15.3 11.0 12.2

20

Maximal soil water suction in growth media during 1969--1971 (cb)

Root weight (g/m 2)

Fresh weight of roots and their percentage of total plant fresh weight. The weight of the various plant parts was determined at the beginning of June 1972, about 4 weeks after cutting was stopped. Irrigation was continued during this period according to preceding year's schedule

TABLE III

15.3

2--3

16.9 11.9 11.0

50

b~

143

separated beds. The soil layer between 30 and 60 cm contained about 65% of the entire weight of the r o o t system, while only 27% was located above this layer and the remaining roots were located deeper than 60 cm. The sparseness of the r o o t system in the raised benches and its relative concentration at a depth below 30 cm in the non-separated benches served probably as i m p o r t a n t factors in determination of the yield.

REFERENCES Hanan, J.J., 1965. Efficiency and effect of irrigation regimes on growth and flowering of snapdragons. Proc. Amer. Soc. hort. Sci., 8 6 : 6 8 1 - - 6 9 2 Hanan, J.J., 1972. Repercussions from water stress. Hort. Science, 7 : 1 0 8 - - 1 1 2 Hanan, J.J. and ~lasper, F.D., 1969. Consumptive water use and response of carnations to three irrigation regimes. J. Amer. Soc. hort. Sci., 9 4 : 7 0 - - 7 2 Holley, W.D. and Goldsberry, K.L., 1968. The effect of reduced stress on rose yield and grade, Bull. Colo. Flower Grs' Ass., No. 216 Plaut, Z., Zieslin, N. and Arnon, I., 1973. The influence of moisture regime on greenhouse rose production in various growth media. Scientia Hort., 1 : 239--250 Shillo, R. and Halevy, A.H., 1964. Experiments in the irrigation of gladioli according to absorption of viscous fluid through stomata. Israel J. agric. Res., 1 4 : 8 9 - - 9 5 White, J.W., 1970. Effects of low moisture stress on the growth of Red American Beauty roses. Bull. Pa Flower Grs, No. 2 3 4 : 3 - - 6 Zieslin, N., Halevy, A.H. and Biran, I., 1973. Sources of variability in greenhouse roses flower production. J. Amer. Soc. hort. Sci., 9 8 : 3 7 1 - - 3 7 8