MSc

A field experiment entitled "Water- nutrient interaction on productivity of
groundnut" was carried out in the Department of Agronomy, College of Horticulture,
Kerala agricultural University, Vellanikkara during Sep-Oct (2001) to Dec-Jan
(2002). The main objective of the experiment was to study the interacting influence
of varying levels of moisture on the availability, absorption and their functional
efficiency of applied and native elements and also to develop a comprehensive
technology for high nutrient use efficiency and crop productivity. The experiment
was laid out in split plot design with three replications. The main plot treatments were
three frequencies of irrigations viz., irrigation at IW/CPE ratios of 0.5, 0.75 and 1.0.
The sub plot treatments were five nutrient levels viz., control, 10-75-75 kg N P20S
K20 ha" (Package of Practices Recommendation), 10-0-75 kg N P20S K20 ha-I, 10-
37.5-75 kgNP20s K20 ha" and 10-75-150 kgNP20s K20 ha".
Results revealed that irrigation had contributed significantly to growth
characters like plant height, leaf production and dry matter production at IW/CPE
ratio of 0.75 or 1.0 which were on par. LA! and total chlorophyll content also showed
similar pattern. The plants that received irrigation at IW/CPE ratio of 0.75 had
recorded the highest pod and kernel yield. The consumptive use increased with
increase in frequency of irrigation and highest Field Water Use Efficiency was
recorded in h(IW/CPE=0.75) but Crop Water Use Efficiency was highest in 11
(IW/CPE=0.5).
The nutrient levels did not produce considerable variation in growth characters
in groundnut. The number of pegs and pods per plant were higher in FJ (10-37.5-75
kg N P20s K20 ha"), which had resulted in highest pod and kernel yield. Due to
haulm: pod ratio, the treatment F3 recorded the highest harvest index. The oil yield
was also highest in F3.

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The content of Nand P uptake was in stem and leaf was highest in F I (10-
37.5-75 kg N P205 K20 ha-I), but K content was higher in F4 (10-75-150 kg N 1>205
K20 ha-I). Irrespective of different stages of growth. Nand P content were higher in
kernel compared to different plant parts of groundnut. The secondary nutrients Mg
and S contents as well as their uptake was also higher in F3 (10-37.5-75 kg N P205
K20 ha-I). Fe and Mn content and uptake were higher in F2. Maximum depletion ofN,
P and K content from soil was found to be in F2 and F3 which were on par.
The plant which receive combination of irrigation at IW/CPE ratio of 1.0 and
nutrient level of 10-37.5-75 kg N P205 K20 ha" recorded the highest pod and kernel
yield as well as uptake of major nutrients. The effect of irrigation was more
pronounced on nutrient concentration in different parts of groundnut towards maturity
of the crop especially with respect to Ca, Mg, S, Fe and Mn. The uptake ofN, P, K,
Ca and Mg increased with increase in frequency of irrigation. Fe and Mn content was
low at higher frequency of irrigation. Available N content of soil increased with
increase in frequency of irrigation but available P and exchangeable K of soil showed
a decreasing trend with increase in frequency.
Soil solution studies revealed that Nand K content of soil solution decreased .
with increase in duration after the irrigation. N content was highest in lowest
frequency of irrigation at field capacity. But K content was high at highest frequency
of irrigation. P content could not be detected in soil solution. The content of Nand K
was not consistent among different duration after irrigation. Ca and Mg content of
soil solution increased with increasing duration after irrigation. But S showed
decrease in trend. Ca, Mg and S content were highest in II (IW/CPE=O.5) and
decreased with increase in frequency of irrigation.
The result indicated that the combination of irrigation at IW/CPE of 1.0 and
nutrient level of 10-37.5-75 kg N P205 K20 ha-lis found to be optimum for groundnut
in terms of growth, yield an uptake of nutrients. The interference of native elements
like Fe and Mn was found to be low at this level of water nutrient interaction.