Response of sunflower (Helianthus annuus) to phosphorus, sulphur, micronutrients and humic acid under irrigated condition on red sandy-loam soil

Abstract

An experiment was conducted during rainy season of 1990   to study the response of sunflower (Helianthus annuus
L.) genotypes (hybrid 'KBSH 1', inbred line 'HA 234 B' and open-pollinated variety 'Morden') to phosphorus, sulphur,
micronutrients (zinc and boron) and humic acid along with recommended doses of N, P and K @39.6 and 50.4 kg/ha
respectively. Both nutrients and genotypes significantly influenced the leaf - area index, seed yield, filled seeds/capitulum, seed filling (%), volume weight, achene and kernel-oil content. The interaction effects were found non-significant. 'KBSH 1 ' gave the highest yield (3 840 kg/ha), being 58 and 94% higher than that of 'Morden' and 'HA 234 B' (2430 and 1 980 kg/ ha respectively). The highest yield (3 070 kg/ha) was recorded with the combination of all nutrients, which was on a parwith the recommended fertilizer + borax dusting @ 2 kg/ha (2 910 kg/ha) and significantly superior to all the other treatments. The yield increased owing to improvement in yield components, viz filled seeds/head (1 066), seed filling (%) (86.2), 1 000 - seed weight (63.9 g) and leaf-area index (3.81). These treatments also influenced the oil (50.3%) and protein (21.9%) contents compared with the control. The nutrients increased the seed-quality parameters such as higher germination (%) after accelerated ageing (61.8%), higher speed of germination (22.2), higher shoot (23.4 cm) and root lengths (20.4 cm), higher vigour index (3 947) and seedling-growth rate (25.1 cm) compared with the control.