DRIP IRRIGATION SCHEDULING AND WATER PRODUCTION FUNCTION FOR GROUNDNUT AND SAFFLOWER
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Date
2019
Authors
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
and safflower” was conducted at the Water Technology Centre, College Farm, College of
Agriculture, Rajendranagar, Hyderabad, Telangana, India during rabi season of 2012-13 and 2013-14.
Two crops viz., groundnut and safflower were tested separately with six irrigation treatments
involving five irrigation levels through drip (0.4, 0.6, 0.8, 1.0 and 1.2 pan evaporation replenishment) in
comparison with one surface check basin irrigation at 1.0 IW/CPE ratio laid out in Randomized Block
Design (RBD) with three replications. Surface drip irrigation system used in the study consisted of 16 mm
integral dripper line laid out on the ground surface along the crop rows at 1.20 m apart for groundnut and
safflower with emitters spaced at 0.40 m on laterals having discharge capacity of 2 LPH. The application rate
was adjusted as per the treatments. Weather elements viz., temperature, relative humidity, rainfall and rainy
days, sunshine hours and wind velocity were also measured during the crop growing seasons.
Growth parameters viz., plant height, LAI, branches per plant and dry matter per plant were
recorded at 30, 60, 90 DAS and at harvest in groundnut and at 20, 40, 60, 80 DAS and at harvest in
safflower. Likewise, yield attributes viz., number of pods plant-1
, number of kernels pod-1
, test weight (100
kernel weight) and shelling percentage for groundnut and number of capitula plant-1
, number of seeds
capitula-1
for safflower and test weight, pod/seed yield, oil content and harvest index were measured at
harvest for both the crops. Water use studies include daily pan evaporation data, irrigation water applied.
From the water use data seasonal crop evapotranspiration, water productivity, crop coefficient, water
production functions, optimization of water and economic ramification were generated. The data generated
on various aspects in this study on effect of irrigation levels on groundnut and safflower were analyzed
through standard statistical methods and logical conclusions were drawn.
Drip irrigation scheduled at 1.0 pan evaporation replenishment (Epan) recorded significantly higher
growth parameters, yield attributes, pod/seed and haulm/stalk yield over drip irrigation scheduled at 0.4, 0.6
Epan and surface check basin irrigation at 1.0 IW/CPE ratio. However, the drip irrigation scheduled at 1.0
Epan was at par with the 0.8 and 1.2 Epan with respect to all the above parameters signifying the importance
of frequent application of optimum amount of water at the root zone of crop to maintain soil moisture status
favorable to plant growth.
Pod yield was found to be significantly and positively correlated to growth viz., plant height (R2
=
0.907*), number of branches plant-1
(R2
= 0.952**), leaf area index (R2
= 0.963**) and dry matter production
(R2
= 0.990***); and yield components viz., number of pods plant-1
(R2
= 0.979***), number of kernels pod-1
(R2
= 0.987***), test weight (R2
= 0.969**), shelling percentage (R2
= 0.985***) and oil content (R2
=
0.930**) for groundnut. Safflower seed yield was also found to be significantly and positively correlated to
growth viz., plant height (R2
= 0.873*), number of branches plant-1
(R2
= 0.985***) and dry matter
production (R2
= 0.964**); and yield components viz., number of capitula plant-1
(R2
= 0.985***), number of
seeds capitulum-1
(R2
= 0.988***), test weight (R2
= 0.999***) and oil content (R2
= 0.971***). Similarly,
correlation studies between growth and yield traits and yield were also showed significant and positive
association between themselves in both the crops.
Water deficits (Crop ET deficit) at different crop growth period of groundnut and safflower (0.4
Epan and 0.6 Epan) caused significant reduction in pod/seed yield. The yield reduction in stress treatments
varied from 200.26 to 73.6 in groundnut and 126.30 to 37.06 in safflower relative to 0.8 Epan treatment on
pooled basis. The reduction in yield observed was due to contemporaneous reduction in growth and yield
traits in these treatments. Similarly, the extent of reduction in yield due to surface check basin irrigation was
to the tune of 62.97 and 50.7 lower than 1.0 Epan and 0.8 Epan, respectively in groundnut and 57.14 and
47.80 lower than 1.0 Epan and 0.8 Epan, respectively in safflower.
The highest seasonal crop ET (261.0 and 265.0 mm in groundnut and safflower, respectively) and
crop ET rates (2.44 and 2.32 mm day-1
in groundnut and safflower, respectively) were recorded in surface
check basin irrigation treatment than rest of the drip irrigation treatments. Among the drip irrigation
schedules, the seasonal crop ET (243.9 mm) and daily crop ET rate (2.28 mm day-1
) in groundnut and 244.5
mm and 2.15 mm day -1 respectively, in safflower were highest at 1.2 Epan treatment compared to remaining
drip treatments. Water productivity in both groundnut and safflower was significantly higher in deficit
irrigation treatment viz., drip irrigation at 0.8 pan evaporation replacement compared to rest of the treatments
owing to on par yield relative to 1.0 Epan treatment.
Crop coefficient (ETc/ETo) was highest with surface check basin irrigation at all the crop growth
stages in both the crops. Optimum crop coefficient was registered with drip irrigation at 0.8 Epan. Further,
optimum yield production was observed at 08 Epan and Kc values recorded at this treatment were also close
to FAO Kc values.
Groundnut crop net irrigation requirement ranged between 23.50 to 127.10 mm at different crop
growth stages with seasonal requirement of 221.90 mm and the peak gross irrigation requirement at source
point amounted to 1441.90 m3
. In case of safflower, the net irrigation requirement ranged between 24.80 mm
to 115.50 mm at different crop growth stages with seasonal requirement of 223.20 mm and the peak gross
irrigation requirement at source point amounted to 1283.77 m3
.
Among all the production functions, the seasonal water production function expressed by quadratic
or second order polynomial for pod and seed yield in both groundnut and safflower crops were found to be
statistically good enough with regard to fitting of the measured data and F-value for testing R2 were highly
significant at P = 0.01.
The predicted maximum pod yield of groundnut was 4130 kg ha-1
during 2012-13 with crop ET of
226.87 mm and 3205.6 kg ha-1
during 2013-14 with crop ET of 198.60 mm beyond which the yield decrease.
The quantity of irrigation water that is economically optimum level (Economic optima) which will maximize
the net return under prevailing market prices (`45.0 kg-1
) worked out to be 212.05 ha-mm with the resultant
pod yield of 3662.2 kg ha-1
. In case of safflower, the predicted maximum seed yield was 1876 and 1731 kg
ha-1 with crop ET of 227.8 mm and 200.3 mm during 2012-13, 2013-14, respectively and the economic
optima with net return under prevailing market prices (` 42.0 kg-1
) worked out to be 214.41 ha-mm with the
resultant seed yield of 1807 kg ha-1
.
At lower levels of crop ET, maximum profit of safflower can be achieved when compared to
groundnut. However, in terms of tonnage, groundnut out yielded safflower at all seasonal water supply levels
through drip. But the cost of the produce play very important role for the final profit, which in turn depends
on selection of the crop, available resources and prevailing weather conditions during crop growth period.
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D10,382