RESPONSE OF SUNFLOWER (HELIANTHUS-ANNUUS) TO PHOSPHORUS, SULFUR, MICRONUTRIENTS AND HUMIC-ACID UNDER IRRIGATED CONDITION ON RED SANDY-LOAM SOIL

An experiment was conducted during rainy season of 1990 to study the r esponse of sunflower (Helianthus annuus L.) genotypes (hybrid 'KBSH 1' , inbred line 'HA 234 B' and open-pollinated variety 'Morden') to phos phorus, sulphur, micronutrients (zinc and boron) and humic acid along with recommended doses of N, P and K @ 39.6 and 50.4 kg/ha respectivel y. Both nutrients and genotypes significantly influenced the leaf-area index, seed yield, filled seeds/capitulum, seed filling (%), volume w eight, achene and kernel-oil content. The interaction effects were fou nd non-significant. 'KBSH 1' gave the highest yield (3 840 kg/ha), bei ng 58 and 94% higher than that of 'Morden' and 'HA 234 B' (2 430 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 par with the re commended fertilizer + borax dusting @ 2 kg/ha (2 910 kg/ha) and signi ficantly superior to all the other treatments. The yield increased owi ng 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 in dex (3.81). These treatments also influenced the oil (50.3%) and prote in (21.9%) contents compared with the control. The nutrients increased the seed-quality parameters such as higher germination (%) after acce lerated ageing (61.8%), higher speed of germination (22.2), higher sho ot (23.4 cm) and root lengths (20.4 cm), higher vigour index (3 947) a nd seedling-growth rate (25.1 cm) compared with the control.