Effect of nitrogen level on the growth , yield & yield components of durum wheat ( Triticum durum ) under supplementary irrigation and rainfed conditions

Abstract

Effect of N level under supplementary irrigation and rainfed conditions on the growth , yield & yield components of durum wheat, cultivar Marjawi, was investigated in two experiments during 1989-90 and 1990 - 91 under the conditions of Jebel El - Akhdar , Libya , using the R. C. B. design. High yield response to N application was observed under supplementary irrigation, while the response was limited under rainfed conditions . Lack of nitrogen caused a significant reduction in total crop dry weight which averaged 29.5% at maturity. Significant differences in the pattern of tillering between the two seasons were observed. Addition of nitrogen significantly increased the number of tillers . However, this increase was not a limiting factor in determining ear number. To increase ear number we need to increase tiller survival not prodution. Grain yield as influenced by N was not a product of one single yield component. However, the compounded yield component , grain number / m2 was highly correlated with yield under supplementary irrigation . Also, grain yield was highly correlated with total crop dry weight at maturity. On the other hand the effect of N on harvest index was small, and the results indicate that factors which influenced yield did so by influencing total dry - matter production rather than influencing the partitioning of dry matter to the grain. Abscence of supplementary irrigation caused significant reductions in grain yield , 1000 grain weight and harvest index.