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ONTOGENY GROWTH AND RADIATION USE EFFICIENCY OF HELIANTHUS ANNUUS L., AS  AFFECTED  BY  HYBRIDS, NITROGENOUS REGIMES AND PLANTING GEOMETRY UNDER IRRIGATED ARID CONDITIONS

A. ZAHOOR¹, M. RIAZ¹, S. AHMAD¹*, H. ALI¹, M.B. KHAN¹, K. JAVED¹, M.A. ANJUM², M. ZIA-UL-HAQ³ AND M.A. KHAN⁴

Abstract: Response of sunflower (Helianthus annuus L.) hybrids in terms of ontogeny growth and radiation use efficiency (RUE) to nitrogenous regimes and planting geometries was studied in two field experiments conducted at Experimental Farm, Bahauddin Zakariya University (BZU), Multan, Pakistan during spring 2009. Variables included in this study were four hybrids and four nitrogenous regimes in experiment 1; three hybrids and three planting geometries in experiment 2. Overall, increasing nitrogenous regimes significantly increased LAI compared to control in experiment 1, while, in experiment 2, the ridge and bed sown crops yielded higher LAI as compared to the flat sown crop. The accumulative leaf, root, stem, head and total dry matter were 63, 51, 211, 58 and 349 g plant^-1, respectively for experiment 1, while, the respective values for experiment 2, were 59.6, 130.5, 135.9, 180.0 and 487.1 g plant^-1, respectively. In the present study, both experiments 1 & 2 resulted in a curvilinear trend for RUE over time of course. Overall, maximum value for RUE for total dry matter accumulation ranged from 1.47 to 2.72 g MJ^-1 in experiment 1, the respective values for experiment 2, were 1.38 to 2.83 g MJ^-1. For growers higher nitrogen rates and bed sowing are good management practices for newly developed sunflower hybrids under irrigated arid conditions. 

¹Departments of Agronomy, ²Horticulture & ³Chemistry, Bahauddin Zakariya University, Multan-60800, Pakistan, ⁴In-Service Agricultural Training Institute,

Sargodha-40100, Pakistan

*Corresponding author’s email: shakeel.agronomy@gmail.com