Effect of Nitrogen Source and Nickel Nutrition on Photosynthetic Pigments and Nitrogen Metabolism of Lisianthus (Eustoma grandiflorum cv. 'Mariachi') Cut Flowers

Recently, nickel (Ni) is introduced as an essential nutrient for higher plants because it is a critical constituent of urease enzyme. This element is necessary for nitrogen (N) metabolism especially when urea is the N form being supplied. The aim of this investigation was to examine the effects of nitrogen source and nickel nutrition on chlorophyll content and nitrogen metabolism in Lisianthus (Eustoma grandiflorum cv. 'Mariachi') plants. In this research, the plants were treated with two N sources, urea and nitrate (sodium nitrate=NaNO3) at 150 mg L -1 , and 4 Ni levels as nickel sulfate (NiSO4·6H2O; 0, 0.25, 0.5, and 0.75 mM). Result show that effect of different levels of nickel and N sources on nitrogen and protein percent was not significant. However, urea-fed plants had a higher percentage of nitrogen compared to nitrate-fed plants. In this study, the highest nitrogen and protein percent were observed in 0.75 mM nickel sulfate. Total chlorophyll as well as chlorophyll a was significantly affected by both N sources and nickel supplements (P<0.01). The highest total chlorophyll and chlorophyll a was observed in urea-fed plants and treatment of 0.25 mM nickel. Although the effects of N sources and nickel supplements were not significant on chlorophyll b, but they followed a similar pattern as chlorophyll a. Generally, it can be concluded that Ni supplements (0.25 mM) improve photosynthetic pigments in urea-fed lisianthus cut flower.