THE INFLUENCE OF HIGH TEMPERATURE ON GROWTH AND YIELD OF EARLY POTATOES UNDER SHORT DAY CONDITION

Indian J. Plant Physiol., Vol. 2, No. 2, pp. 93-97 (ApriL-June, 1997)

THE INFLUENCE OF HIGH TEMPERATURE ON GROWTH AND YIELD OF EARLY

POTATOES UNDER SHORT DAY CONDITION

R. EZEKIELANDS.C.BHARGAVA~

Central Potato Research Institute, Shimla, Himachal Pradesh

Received on 10 Nov., 1995, Revised on 12 Nov. 1996

SUMMARY

The effect of high temperature on the growth and yield of early potatoes in north Indian plains was studied in relation to three different planting dates. The rate of leaf appearance was related to the rate of elongation of the main stem in Kufri chandramukhi but not in Kufri Lalima. The Heat Use Efficiency was low in the early crop. The low yield obtained in the early crop was mainly due to a smaller and short lived canopy leading to reduced interception of solar radiation. More than the reduction in overall plant growth, high temperature lowered tuber yield through reduced partitioning of photosynthates to the tubers.

INTRODUCTION

In western Indo-Gangetic plains, potato is normally planted in the middle of October when the day/night temperature is 31/l6°C. Early crop is planted around 15 September when the temperature is 32/23°C. September plantings have been found to yield lesser when compared to early October planting (CPRI, 1982; Kishore, 1983). Though early planting is common in Indo-Gangetic plains, little attention has been given to the growth and development of the early crop and the adverse effect of high temperatures during September/October. Therefore, an attempt was made to analyse the growth of early potato crop in relation to three other dates of plantings.

MATERIALS AND METHODS

The field experiments were carried out at Central Potato Research Station, Modipuram (29°4'N, 77° 46'E, 237m above MSL) during 1991-92. Two potato cultivars viz. Kufri chandramukhi (Early-90 days) and Kufri lalima (Medium-11 0 days) was included in this study. Early planting was done on 16 September (D

J

and I November (0₄) during 1991 and 1992. Seed tubers

*Division of Plant Physiology, lARl, New Delhi- 110012

indian J. Plant Phy.riol., Vol. 2, No. 2, pp. 93-97 (April.-June, 1997)

of approximately 50 g were planted at a spacing of 60 x 25 em. Fertilizer was applied to the sandy loan1 soil at the rate of 150 kg N, 80 kg P ₂ 0 ₅ and I 00 kg K

2 0 per hectare.

Nitrogen was given in split application, 75 kg N as basal dose and 75 kg Nat the time of earthing up. The design followed was Randomised Complete Block with three replications. The crop was irrigated at I 0-15 day interval depending upon the weather conditions.

R. EZEKIEL AND S.C. BHARGAVA

The leaf area was measured using leaf area meter (Ll-COR, USA). The per cent ground cover was measured periodically beginning from 20 OAP, as per the method given by Burstall and Harris (1983). Crop growth rate (CGR) was calculated as described by Radford (1967). At crop maturity tuber number and yield were recorded. Maximum and minimum air temperature were recorded daily. Average fortnightly air temperatures are given in

Table I. Heat use efficiencv (HUE) was computed by dividing biomass with heat units (accumulated day-degrees) (Sastry et al. 1985).

RESULTS AND DISCUSSION

In early planting (OJ 50 per cent plants emerged in 18 and 20 days in Kufri Chandramuk.hi and Kufri Lalima respectively as compared to 15 and 16 days in 03 . High

temperatures delayed plant emergence by 3-4 days in early planting. The rate of sprout growth is slowed by

high temperatures leading to delayed emergence. Tuber initiation occurred around 35 DAP in 01 and 30 DAP in

0₃ in both the cultivars. Thus high temperatures delayed tuber initiation by 5 days in early planting. High temperatures per se delay the tuber initiation process

(Nowak and Colebome, 1989). Table I. Average fortnightly air temperatures (0_{C) during}

the crop seasons.

Days interval 1991-92

Period Max.

Sept. 16-30 32.4

Oct. 1-15 31.5

16-31 30.2

Nov. 1-15 24.5

16-30 22.2

Dec. 1-15 23.4

16-31 18.7

Jan. 1- I 5 I 9.2

16-31 21.5

Feb. 1-15 18.9

16-28 23.8

1992-93

Min. Max.

22.6 30.2

16.1 32.3

14.8 30.5

11.9 28.5

9.0 23.4

8.5 22.0

9.4 22.4

6.9 18.7

8.9 17.8

9.7 24.7

9.0 21.2

Min 21.5

18.0

15.1

12.8

9.8

7.1

6.0

7.6

4.7

10.4

9.4

Planting date changes plant height and leaf appearance and thus plant fom1. The rate of leaf appearance was linear with time. The leaf production per day was greater in the early planting (Table II)" and the differences were more pronounced in Kufri chandramuk.hi. But when expressed in day-degrees there was not much difference in the number of leaves produced per day-degree. The stem elongation rate per day in early planting was more in Kufri chandramuk.hi than in Kufri lalima. However, the stem elongation rate per day-degree was lesser in early planting and more in normal and delayed planting in both the cultivars (Table II). In Kufri chandramuk.hi leaf

Table II. Rate of leaf appearance and stem elongation in chronological and thermal time for two potato varieties

Variety

Kufri

chandramukhi

Kufri

lalima

94

Treatment Leaves

(dayl)

0.20

0.15

0.13

0.12

0.17

0.14

0.14

0.15

Leaves Stern Stem

( day-degree·1

) elongation elongation

(ern day1

) (em day-degree·1)

0.013 0.59 0.038

O.Dl1 0.49 0.037

0.011 0.46 0.041

0.012 0.33 0.048

0.011 0.47 0.034

0.010 0.42 0.039

0.012 0.87 0.069

0.014 0.70 0.062

TEMPERATURE EFFECT ON POTATO

production per day and the rate of stem elongation were positively correlated (r = 0.909). But when expressed in day-degrees there was no association between the two variables (r= 0.070). In Kufri Lalima, leaf production per day and the rate of stem elongation were negatively correlated (r = 0.412). But when expressed in day degrees, there was

a

Use of thermal time reversed this relationship. These results suggested that in Kufri chandramukhi leaf number increases with stem length whereas in Kufri lalima the same number of leaves can be borne on long or short stems.

There were not much differences between the treatments in heat use efficiency (HUE) during the first 40 DAP (Table III). The HUE was greatly influenced by the

production (r = 0.98) but negatively correlated with growing day-degree (r =- 0.625). The HUE during any growth stage was largely influenced by the biomass produced during that period (R2

₌

strong, positive correlation between HUE and CGR ( r= 0.99) with an R2 _{value of 0.97. The HUE and CGR}

facilitate relative assessment of crop response to prevailing thermal environment at different growth stages (Singh et

al., 1991).

At high temperatures stem growth was favoured at the expense of leaf growth. In Kufri chandramukhi, of the total above ground biomass produced in D₁ 43% accumulated in stems and 57% in leaves. Whereas in D, it was 28% and 72% respectively. A similar trend was observed in Kufri lalima also. In the early crop, high temperatures increased leaf number (Table IV) but reduced

Table III. Heat use efficiency (HUE) and crop growth rate (CGR) of potato crop (above ground biomass) at different growth stages.

Treatment Days Growing Kufri Chandramukhi Kufri Lalima

after planting

0-40 40-60 60-80 0-40 40-60 60-80 0-40 40-60 60-80 0-40 40-50 60-80

day degress (Heat units) 762 284 235 674 234 219 540 239 19-464 218 195

tiUE (gm-2 day-' degree-') 0.12 0.08 O.Dl

0.10 0.06 0.23 0.10 0.08 0.32 0.12 0.06 0.17

crop growth stage. It was less during the early tuber bulking phase i.e. between 40 and 60 DAP and maximum in the later stage i.e. between 60 and 80 DAP. However, in the early crop, the HUE was higher between 40 and 60 DAP since maximum crop growth occurred during this period. The HUE was positively correlated with biomass

Indian J. Plant Physiol., Vol. 2, No. 2, pp. 93-97 (ApriL-June, 1997)

CGR HUE CGR

(gm-2 (gm-2 (gm-2

day-') day day-')

degree-') 0.12

1.21 0.21 2.98

0.15 0.04 0.61

0.12

0.75 0.08 0.94

2.56 0.35 3.89

0.16

0.94 0.06 0.67

3.02 0.44 4.22

0.16

0.71 0.06 0.66

1.65 0.39 3.77

leaf size drastically as the period of expansion was reduced, resulting in lower leaf area index (LAI). The maximum LAI reached in Kufri chandramukhi was 1.9, 2.4, 2.8, and 2.7 in Dl' 0₂, 0

3 and 04 respectively. The

corresponding values for Kufri lalima were 2.4, 3.1, 3.0 and 3.3.

R. EZEKIEL AND S.C. l3llARGA VA

Table IV. Effect of planting date on leaf number, shoot dry weight, harvest index and tuber yield ( 1991-92 and

1992-93).

Varidy Treatment Leaf No./

st.::m

Shoot dry wt Harvest Tuber Tuber Yield Tuber

(g. m ') Index 1991-92 Number (!;/ha ') mtmhcr

(m')

Knlri dumdramukhi

Kul'ri Ia lima

LSJJ(OO'i) Treatment

Vandy

Interaction

l\

D, D,

o.

D,

o,

D,

J),

N.S. =Not-significant

20.2 122')

!3.5 134.5

11.7 1370

11.7 104.9

17.2 164.0

14.5 179.9

15.5 183.3

15.2 !tl2.8

](i _17.2

N.S 12.1

2.3 N.S.

The peak ground cover achieved in early planting was less than the other three plantings and declined rapidly after attaining the peak (Fig. 1). This is brought out more clearly in Kufri lalima where the peak was narrow in D₁ 'v\hile in other three plantings. the peak crop cover was retained for a longer time before it began to decline. High temperature field conditions arc reported to restnct the size and duration of crop cover in potato (Allen and Scott. 1991 ). Total dry matter production is determined by the amount of radiation intercepted by crops. In the early crop. supraoptimal temperatures restricted leaf growth and hastened maturity As a result the early crop suffered from a reduced and short lived canopy leading to reduced interception of radiation (Midmore. 19X4).

Though the top growth was higher upto 60 DAP in the early planting the harvest index (HI) was quite low. The HI was only 0.37 in 0₁ when the tubers were harvested at

..f() DAP. whereas it \vas 0.62 in D, for the same period.

The lower HI could be attributed to higher temperature of 3 l/16"C m D ₁ during the first 40 days. Reduc.cd partitioning

(g. ha 1

) (111 ') 1992-93

0.57 87.3 31.4 78.0 29.:j

O.tl8 154.6 27.3 195.3 49.5

0.80 303.8 t)8(j 309.5 85.G

() 82 2(,8.5 58.9 23tJ.4 79.7

0.52 94.4 320 135.6 38.1

0.76 291.4 49.!1 26Ci.7 54.7

0.77 334.2 68.9 291.5 93.7

0.78 315.9 92.9 30<U 94.9

{).(}5 46.2 5.3 22.7 12.8

N.S. 32.G

:u

O.o7 65 3 7.6 N.S. N.S.

of photosynthate to the tubers is probably the major problem resulting from high temperatures (Ewing, I 98 I). The HI improved between 40 and 60 DAP, when the temperature was 25/ l2°C but was still low when compared to other three plantings (Table IV). Generally. it is believed that short duration varieties are preferred for early plantings. But the results reported here suggest that medium cultivars can also be grown as early crops.

The early crop yield ranged from 78 to '67 q/ha in Kufri chandramukhi and from 94 to 135 q/ha in Kufn lalima (Table IV). The lo'vv.;:r tuber yield 111 the early crop

was due to decrease in number as well as size of tubers Though enough stolons were produced in the early crop. fewer stolon tips developed into sizeable tubers. The tuber yield was maximum in the normal planting (OJ Larger leaf cat)opy cover leading to greater interception of radiation coupled with efficient partitioning of photosynthates into tubers led to higher tuber yield in D,. Increased productivity in early crop is a desired goal Higher yield of early potatoes is dependent upon the ability to emerge, develop and maintain the leaf canopies in an unfavourable en vi ro1m1ent and increased partitioning

TEMJ>ERATlfRE EFFECT ON POTAT<)

of photosynthatt; accumulated in the haulms to the tubers. These attributes can be expected in a heat tolerant genotype Potato genotypes tolerant to high temperatures are needed to get better yield of early potatoes.

0

/o Ground cover 1 00

I

o-,-;1~:::-

oL':.__ __,, _ _

0 20 40 60

" - - - 1 ______ _ 80

,. '

100

Kutri Chondromukhi

0 *

*

0

20 _{40 60 80 too}

120

12~

Fig: I. Per cent crop wver in potato cvs Kufh lalima and Kufri chandramukhi at different times atditlerent planting dates in the field.

!nJ~tm J !'!ant Physzol .. Vol. 2. No. 2, pp. 93-97 (.'\prii.-.JunG. 1997)

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