Standardisation of foliar spray of boron for correction of brown rot and for increasing yield of cauliflower (Brassica oleracea convar botrytis var botrytis) in Bihar plateau

Abstract

Field experiment was conducted during 1989-92 at Ranchi on a red sandy loam (Ultic Haplustalf) deficient in
available boron (0.01 flg/g hot-water soluble (HWS) B] with 'Pusa Snow Ball K-1' cauliflower. Foliar application of
B was as good as soil application @ 1.5 kg B/ha in increasing curd yield, B and Ca content of leaf and Ca : B ratio in
leaf-tissue. Reduction of curd-rot was signiticant compared to control but of lower order than that achieved with soil
application. Among spray concentrations (0.125 - 4.00 % boric acid) and spray numbers (1- 4, 10 days after transplanting
at 15 days interval), the highest curd yield (14.73 tonnes/ha) was obtained at 0.125 % spray concentration
while the lowest curd-yield of 6.87 tonnes/ha curd yield was obtained at control. The curd-yield declined at higher
spray concentrations due to excess B applied, the lowest being at 4.00% boric acid (12.41 tonnes/ha). Spray concentration
above 1.00% and 2 sprays caused irreversible yellowing/scorching, reduction of plant-growth and high residual
hot water soluble B in soil (0.95 - 3.90 flg/g). Application of 3 sprays was adequate. Among lower spray concentrations
(0.025 - 0.125%) applied in 3 sprays, the curd-yield increased with that of spray concentration (18.32 - 21.81
tonnes/ha) while the curd-rot decreased (51 - 2%). Foliar application of 3 sprays of 0.125% boric acid was optimum
for high curd-yield (23.46 tonnes/ha, 76% higher than the control), low curd-rot (5%), negligible residual hot water
soluble B in soil (0.11 flg/g) and high net returns per rupee invested (Rs 4.74) corresponding to 23.45 flg/g of B and
Ca:B ratio of 678 in leaf-tissue.