MSc

Intensive cropping and imbalanced use of high analysis fertilizers have induced deficiencies of micronutrients in many part of the country. To achieve high yields and sustain the same over years, it become very pertinent to foresee the emerging nutrient deficiencies and to evolve suitable ameliorating technologies. Deficiency of micronutrients, especially deficiency of zinc and boron, is very prominent in Kerala soils. In this context an experiment entitled ‘Micronutrient management for okra [Abelmoschus esculentus (L.) Moench] under different irrigation methods’ was conducted from December 2018 to March 2019 at Water Management Research Unit, Vellanikkara with the objective to study the effect of foliar application of micronutrients on okra under conventional and drip irrigated conditions.
Treatments consisted of foliar sprays of zinc as ZnSO4 (0.5%), boron as Solubor® (0.5%), combination of zinc and boron (ZnSO4 (0.5%) + Solubor® (0.5%)), and KAU multi nutrient mix (Sampoorna) (0.5%) at three weeks interval and these treatments were tested against treatment without foliar application of micronutrients both under drip irrigation and conventional irrigation. All the treatments were supplied with soil test based application of NPK at recommended dose and FYM at 20 t/ha.
The result of the study indicated that performance of okra under drip and conventional irrigation showed varied response to foliar application of micronutrients. Under drip irrigated condition, foliar application of KAU multi mix application resulted in highest yield (16.41 t/ha). Under conventional irrigation, foliar application of zinc gave highest yield (11.94 t/ha) and soil test based application of NPK alone without micronutrient application was found to be equally good as zinc application (11.53 t/ha). Under drip irrigated condition, foliar application of zinc (ZnSO4 @ 0.5%) gave higher yield than treatment without foliar application of micronutrients. Pre experimental soil analysis data indicated that the soils at drip and conventional irrigation fields were not

deficient in zinc but were deficient in boron. Even then foliar application of zinc (ZnSO4 @ 0.5%) gave good yield response under both drip and conventional irrigation system. Application of boron either alone or in combination with zinc caused the development of phytotoxicity symptoms at the time of spraying, and this may have led to reduced yield performance of okra under both conditions. Under conventional irrigation foliar application of micronutrients could not produce any yield or economic advantage than soil test based application of fertilizers and FYM alone without micronutrient application since this treatment could provide sufficient nutrients for the growth and development of okra. Foliar application of micronutrients caused significant variation in the content and uptake of primary, secondary and micronutrients of okra plants both under drip and conventional irrigation. Under both the irrigated conditions, uptake of N, P and K at harvesting stage were higher for treatment without foliar application of micronutrients. Zinc application led to an increasing trend in zinc uptake during period of application and then reduced subsequently. Boron uptake was found higher in boron applied treatments. The micronutrient status of soil after the experiment in both the irrigated conditions was found to increase compared to pre experimental soil status. This may be due to application of FYM which supplied sufficient quantity of micronutrients to soil. Under drip irrigated condition, foliar application of KAU multi mix was found economically superior with a B: C ratio of 3.03. Under conventional irrigation, the highest B: C ratio (2.38) was obtained for treatment without foliar application of micronutrients. Foliar application of micronutrients showed no economic benefit under conventional irrigation.
Result of the study indicated that foliar application of KAU multi mix to drip irrigated okra was found to economically beneficial. But under drip irrigated and conventional irrigated condition, foliar application of boron alone or in combination with zinc showed no significant economic benefit.