| 【Objective】Theoretical basis for stable yield cultivation of rice under shading environment will be
provided based on the exploration of the effect of panicle nitrogen (N) fertilizer application on rice yield reduction caused by
shading environment at young panicle differentiation stage.【Method】The Guinongzhan, a super rice variety of Guangdong
province, was selected as test material to conduct split plot experiment. At second young panicle differentiation stage, four
different panicle N fertilizer applications of 0 kg/hm2 (N0), 22.5 kg/hm2 (N1), 37.5 kg/hm2 (N2), 52.5 kg/hm2 (N3) were set as main part. Four shading treatments were set as the secondary part: not shading from the second young panicle differentiation
stage to maturity (S0), shading from the second young panicle differentiation stage to full heading stage (S1), shading from full
heading stage to maturity (S2), and shading from the second young panicle differentiation stage to maturity (S3). The effects
of different N fertilizer amount at second young panicle differentiation stage and different shading time after the young spike
differentiation on rice growing process, stem tiller characteristics, yield and its components were studied.【Result】Under
different N fertilizer application amount, yields all showed as:S0 ＞ S1 ＞ S2 ＞ S3. Compared with S0, yields of S1, S2 and S3
significantly decreased 32.0%, 52.7% and 67.8%, respectively. The increment of N fertilizer reduced the yield reduction effect
resulted by shading. Compared with N1, yields of N2 and N3 under S1, S2 and S3 increased 3.9% and 4.3%, 4.4% and 6.8%，
0.9% and 3.1% , respectively. Meanwhile, the increment of N fertilizer prolonged grain filling stage, decreased the reduction
range of spike rate, effective panicle number, filled grains and 1 000-grain weight.【Conclusion】The increasing application of
panicle N fertilizer application could prolong the grain-filling of rice young panicle differentiation stage encountered low light,
and reduce the effect of shading on yield and its components, which decreased the yield reduction extent caused by shading. The
increasing application of N fertilizer had the best effect on the stable production of rice in S2, and then followed by S1 treatment. |
