Response of sunflower hybrids to management practices under irrigated arid-environment
Two field experiments were established at Research Farm, Bahauddin Zakariya University, (BZU) Multan, Pakistan, during the spring season of 2009 to study the interactive effect of sunflower (Helianthus annuus L.) hybrids in terms of growth, fraction of intercepted radiation (Fi), intercepted photo-synthetically active radiation (PAR), yield components and oil contents to planting geometries and nitrogen rates. Experiment 1 comprised nine treatments having combinations of three hybrids (H1 = 19012; H2 = Hysun-33; H3 = DK-4040) and three planting geometries (PG1 = flat sowing; PG2 = ridge sowing; PG3 = bed sowing) while, experiment 2 comprised 16 treatments having combinations of four hybrids (H1 = 00989; H2 = 01087; H3 = 00997; H4 = 010226) and four nitrogen rates (N0 = control; N1 = 75; N2 = 150 and N3 = 225 kg ha-1). The results revealed that, the ontogeny maximum plant height ranged from 32 to 216 cm and from 36 to 299 cm in experiments 1 and 2, respectively. The ontogeny maximum number of leaves plant-1 were 21, 32, 28, 21 and 14 in experiment 1 and 20, 33, 29, 20 and 9 in experiment 2, respectively on respective harvest dates. The ontogeny maximum head diameter was 17, 22 and 25 cm and 20, 21 and 29 cm on respective dates for experiments 1 and 2, respectively. The ontogeny Fi values for experiments 1 and 2, ranged from 0.11 to 0.99 and from 0.09 to 0.99, respectively. The cumulative intercepted PAR ranged from 492 to 812 MJ m-2 and from 627 to 897 MJ m-2 in experiments 1 and 2, respectively. The achene weight ranged from 69.7 to 127.5 g and from 65.4 to 93.4 g in experiments 1 and 2, respectively. The number of achenes head-1 ranged from 919 to 1868 and 925 to 1678 for experiments 1 and 2, respectively. The achene oil contents ranged from 38.1 to 43.1% and 34.5 to 47.6% for experiments 1 and 2, respectively. However, average oil contents value was 41% for both experiments. From the results, the use of higher nitrogen rates and ridge or bed sowing techniques are recommended for the management practices for the newly developed sunflower hybrids
Key words: Sunflower hybrids, planting geometries, nitrogen rates, intercepted PAR.