An Approach To The Screening Index For Low Nitrogen Tolerant Rice And Its Selection

A field trial was carried out to evaluate 106 rice lines under N stress and normal N supply conditions for plant height(PH),panicle length(PL),panicle number(PN),biomass yield(BY),single yield(SY),1000-grain weight(GW) and seed set(SS) in mature stage to research indexes for screening low nitrogen tolerant rice. The index of resistance to low nitrogen (R) was defined as the sum of relative plant height (RPH),relative panicle number (RPN),relative biomass yield (RBY),relative single yield(RSY) and relative seed set (RSS) (low N supply /normal N supply) .And according to the R value, 106 rice lines were evaluated for its tolerance to low nitrogen. The main results were as follows:①Low nitrogen condition had stress effects on the growth of rice. The values of rice traits researched under low nitrogen condition except seed set were smaller than the values of rice traits under normal nitrogen condition. PN,BY and SY were more sensitive to low nitrogen condition than PH,PL,GW,SS。②Tolerance to low nitrogen stress of rice had great differences among rice lines. The variations varied from 6.84% to 18.69%.③RPN,RBY and RSY were more sensitive to low nitrogen stress(the average were 79.8%,77.83%,81.64%,respectivly). RPH,RPL,RGW and RSS were less sensitive to low nitrogen stress(the average were 97.07%,98.72%,99.94%,102.23%,repectively ).④RPN,RBY and RSY exhibited significant variations in different rice lines(the CV were 21.97%, 21.29% and 22.13%, respectively). RPH,RPL,RGW and RSS exhibited small variations in different rice lines(the CV were 3.59%,8.34%,5.50%,9.58%, respectively).⑤PH,PN,BY,SY and SS in mature stage would be effective screening indexes for screening low nitrogen tolerant rice.⑥The index of resistance to low nitrogen (R) was defined as the sum of RPH,RPN,RBY,RSY and RSS .According to the R value, 106 rice lines were divided into four groups, and the tolerance level to low nitrogen increased from the first group to the fourth group. Thirteen rice lines tolerant to low nitrogen and twenty-three nitrogen- sensitive rice lines were found in this research.