The Effects Of Light Intensity And Nitrogen Ratios On Metabolism Of Nitrogen Of Grape Plantlets In Vitro

The effect of light intensity and different nitrogen form and ratios on growth and metabolism of nitrogen were studied. The grape plantlets in vitro Red Globe was cultivated with the media under three kinds of light intensities (lOOOlx, 30001x, 5000lx,) and four kinds of nitrogen form and ratios (NH4+-N to NO3-- N was 10 : 0, 5 : 5, 0 : 10 and 0.8 : 9.2). The results are as follows:Under lOOOlx light intensity, with the improved 65 media the heights of grape plantlets in vitro were the highest but thinnest, the stem fresh weight was the largest under 5000lx light intensity. Furthermore, under l000lx light intensity, the length of roots treated with sole nitrogen source of NO3- -N was better than others. When NO3--N as the sole nitrogen source the average of root and fresh weight under 3000lx were the largest in all treatments. But under 50001x light intensity, the grape plantlets -in vitro was inhibited when NH4--N is the sole nitrogen source, all leaves became red, and some were withered even to die.The results showed that when the ratio of NH4-- N to NO3- -N was 5 : 5 under 5000lx light intensity, the chlorophyll content was the highest in all treatments. The content of soluble sugar and soluble protein were improved with the increase of light intensity. The content of soluble sugar and soluble protein were the highest with the ratio of NH4--N to NO3- - N was 0.8 : 9.2 by the light intensity of 5000lx. The results indicated that GS(glutamine synthetase) activity increased with the increase of light intensity and the ratio of NH4+-N. In comparison with other treatments GS activity was the highest, when the ratio of NH4+ to NO3- was 5 : 5 under 5000lx light intensity. NR(Nitrate Reductase) activity and NO3-- N accumulation in grape plantlets in vitro decreased with the increase of the ratio of NH4+-N. The activity of NR was increased by increased light intensity, at the same time nitrate accumulation decreased. On the contrary, under low light intensity, NR activity decreased and nitrate accumulation increased. NR activity was the highest under 5000lx light intensity with the ratio of NH4+ to NO3- was 0 : 10 and nitrate accumulation was the highest by the light intensity of lOOOlx. Nitrate accumulation was significantly negatively correlated to the activity of NR.