Effects of foliar fertilizer and panicle fertilizer interaction on photosynthetic characteristics， yield traits and rice quality of rice-shrimp co-cropping after rice panicle pumping

【Objective】The effects of foliar fertilizer and panicle fertilizer interaction on the photosynthetic physiological characteristics，yield traits and rice quality of rice under the rice-shrimp co-cropping mode were studied. The appropriate combination of foliar fertilizer and panicle fertilizer was screened to provide reference for the high-yield and high-quality cultivation of rice under the rice-shrimp co-cropping mode.【Method】Taking the rice variety Jingxiangyou 72 as the test material，a two-factor［the foliar fertilizer treatment of Tanyang No.1（F）and panicle fertilizer level（P）］randomized block experimental design was adopted. There were two levels of foliar fertilizer without spraying treatment（F₀）and with spraying treatment（F₁），and three levels of panicle fertilizer topdressing compound fertilizer of 0 kg/ha（P₀），75 kg/ha （P₁）and 150 kg/ha（P₂）for a total of 6 treatments. Leaf SPAD value，enzyme activity，malondialdehyde （MDA）content and soluble sugar content were determined on day 7 after foliar fertilizer spraying，and yield traits and rice quality were determined after rice maturity.【Result】Spraying the foliar fertilizer of Tanyang No.1 and panicle fertilizer topdressing compound fertilizer could improve the photosynthetic function and antioxidant capacity of rice flag leaves to different degrees. Compared with no spraying treatment，foliar fertilizer treatment could increase the SPAD value of rice flag leaves by 2.3%-10.5%，soluble sugar content by 17.1%-34.5%，ribulose diphosphate carboxylase（Rubisco）activity by 26.4%-53.6%，superoxide dismutase（SOD）activity by 9.2%-45.1%，peroxidase（POD）activity by 2.2%-7.2%，and reduce MDA content by 16.7%-41.4%. Among that，F₁P₂ treatment was effective on increasing the Rubisco activity and reducing MDA content of rice flag leaves，and F₁P₁ treatment was effective on increasing the SPAD value，soluble sugar content，SOD and POD activities of rice flag leaves. From the perspective of yield，spraying foliar fertilizer and panicle fertilizer topdressing compound fertilizer could increase rice yield，and spraying foliar fertilizer could significantly increase rice yield by 14.6%-24.5% compared with no foliar fertilizer treatment（P＜0.05，the same below），of which F₁P₁ treatment had the highest number of grains per ear，seed setting rate and rice yield. From the perspective of quality，spraying foliar fertilizer and panicle fertilizer topdressing compound fertilizer could improve the quality of rice to different degrees. Compared with no foliar fertilizer treatment，spraying foliar fertilizer could increase the whole polished rice rate by 2.2%- 2.5%，reduce the chalky grain rate of rice by 29.2%-32.4%，reduce the chalkiness degree by 7.1%-31.8%，and reduce the total protein content of rice by 8.6%-9.7%. Among that，F₁P₂ treatment could significantly improve the whole polished rice rate，F₁P₁ treatment could significantly reduce the chalky grain rate of rice，chalkiness degree and total protein content. The results of the correlation between the photosynthetic physiological indexes of rice flag leaves and rice yield with rice quality traits showed that rice yield and the whole polished rice rate were extremely significantly positively correlated with SPAD value，soluble sugar content and Rubisco，SOD and POD activities of rice flag leaves（P＜0.01，the same below）， and were extremely significantly and significantly negatively correlated with MDA content respectively.【Conclusion】The panicle fertilizer topdressing compound fertilizer of 75 kg/ha and the spraying of the foliar fertilizer of Tanyang No.1 once during panicle pumping 50% period has good comprehensive effect on improving rice yield and rice quality，having high promotion and application value in rice production in rice with rice-shrimp co-cropping mode.