Effect of nitrogen fertilizers on root criteria, pigments and carbohydrates of Vignasinensis L. and Helianthus annuus L. plants.

Abstract

The objective of this study was to investigate the effects of different nitrogen fertilizers (potassium nitrate and / or urea) on root growth, leaf area ratio, pigments content and carbohydrate content of leguminous plant Vigna sinensis and non-leguminous plant Helianthus annuus, throughout two vegetative stages. Root criteria,in general non-significantly affected by the used source of nitrogen during the two vegetative stages of cowpea and sunflower plans growth. Concerning the leaf area ratio, except for the observed non-significant increase in response to treatment with 100% potassium nitrate + 100% urea at second stage, the other treatments was non-significantly decreased this ratio during the two vegetative stages of the two plants. Total chlorophyll and total pigments were increased by the used treatments at first stage of cowpea growth while these parameters were decreased during the second stage and vice versa in case of sunflower plant. Sucrose content of the two plants, was significantly increased by all used treatments at first vegetative stage. On the other hand, the different treatments led to a general increase in the determined carbohydrates (total soluble sugars-sucrose-polysaccharides-total carbohydrates) as compared to control values during second stage of the two plants. The result of this investigation demonstrated that, nitrogen fertilizers has an overall positive influence on growth, photosynthetic pigments and sugars especially in case of using (50% potassium nitrate + 50% urea) and the magnitude of response was more pronounced in case of cowpea plant.