Effect of Nitrogen Application Rates on the Chlorophyll Content and Photosynthetic Characteristics of Green Rice

PurposeTo explore high-yield and high-quality cultivation conditions of Japanese green rice variety ND4 in Sichuan.

Method0 (N0), 90 kg/hm² (N90), 135 kg/hm² (N135), 180 kg/hm² (N180) and 225 kg/hm² (N225) nitrogen application were set, and N0 as a control. The effect of nitrogen application rates on the chlorophyll content, yield and photosynthetic characteristics of green rice were studied.

ResultThe contents of chlorophyll a, chlorophyll b and total phenols in green rice caryopsis decreased with the growth process. Among them, the decline rate was the fastest from 15 to 20 days after anthesis; the total phenol content increased with the increase of nitrogen application, but the difference was not significant (P>0.05) under the treatment of middle and high nitrogen (N135, N180 and N225) in the mature period; under the treatment of high nitrogen (N180 and N225), the rate of decrease of the chlorophyll content of the caryopsis with the advance of the mature period. The pigments were lower and stable; the chlorophyll content and net photosynthetic rate of the flag leaves increased first and then decreased with the progress of the growth process, and reached a peak at 20 days after anthesis. The effective panicle and 1000-grain weight increased with the increase of nitrogen application. The spike number, seed setting rate and yield increased firstly and then decreased with the increase of nitrogen application. The yield was the highest under N180 treatment, which was 4.66 t/hm².

ConclusionThe high-yield cultivation conditions of green rice under this test condition are nitrogen application rate of 180 kg/hm², and green rice with higher chlorophyll content can be harvested at the curing stage (30 days after flowering).