Tissue n-content determination and yield assessment in nitrogen fertilized sunflower (<i>Helianthus annuus </i>L.) in Maiduguri, Sudan Savanna, Nigeria

Abstract

To determine N contents of various sunflower parts under nitrogen-treated field conditions, experiment was conducted during the rainy seasons of 2010 and 2011 at University of Maiduguri Teaching and Research Farm, Faculty of Agriculture in Sudan savanna of Nigeria. The treatments (0, 30, 60, 90 and 120 Kg N ha^-1) were arranged in Randomised Complete Block Design (RCBD) and replicated three times. Urea (46%N) was split-applied to 2 weeks after sowing (WAS) and to first flowering; and fields were kept weed-free in order to avoid nutrient loss to weed uptake. Various plant parts were collected at maturity and analysed in the laboratory to determine their N-contents. Data obtained were statistically separated using DMRT. Result on tissue analysis revealed increase in mean root N content which had 4.99% at 30 Kg N ha^-1, while the stem N content increased with higher N rate of 90 Kg ha^-1 and gave 7.16% in the two years mean. Mean leaf N content for the years however influenced significantly the leaf N-content with 60 Kg N ha^-1 which recorded 17.03% and higher nitrogen rate of 90 Kg N ha^-1 influenced grain N uptake of 15.77% for the two years. Application of 60 Kg N ha^-1 recorded mean 1000-grain weight (43.03g) for the two years, while higher N rate of 90 Kg ha^-1 increased mean grain yield for the two years (1928.5 Kg ha^-1). It is concluded that N applied at 90 Kg ha^-1 did not only influence increase in grain N content, but also meet plant demand for grain yield, which could mean that the grain N uptake contributed to partitioning of materials needed to fulfil the physiological requirements which translated to grain development.