Effects Of Foliar Magnesium Application On Rice Yield And Quality

In order to determine the effects of Mg application on the yield and quality of rice flowers,field experiments were conducted in 2019 and 2020.At heading stage,three concentrations of Mg application on leaves were set:Mg1（5%Mg SO₄·7H₂O）;Mg2（10%Mg SO₄·7H₂O）;Mg3（20%Mg SO₄·7H₂O）and Mg0（no Mg0）were used as control.The changes of nutrient absorption,substance accumulation,leaf senescence,yield and quality of rice were investigated.The main research results are as follows:1.Folial Mg application increased the nutrient content of rice plants and promoted nutrient accumulation.The contents of N,P and K,K/Mg ratio and N/Mg ratio in stem,leaf and panicle were significantly increased 10 and 30 days after foliar Mg application.The Mg content in stem was significantly increased 10 days after foliar Mg application,and the Mg content in green leaf was significantly increased 30 days after foliar Mg application.At the same time,Mg application increased the accumulation of N,P,K and Mg in rice,and tended to increase with the increase of Mg application.At maturity stage,foliar Mg application significantly increased the content of n,P and K/Mg in panicle,and increased the accumulation of N,P,K and Mg in panicle.2.Foliar Mg application increased dry matter accumulation and promoted assimilation material transport.Leaf Mg application had no significant effect on the total dry weight of rice during the whole growth period.Compared with Mg0,leaf and panicle dry weight increased by 4.58%and16.67%on average 10 days after Mg application（P<0.05）.Mg1 and Mg2 had no significant effect on the total dry weight of rice,while Mg3 increased the dry matter weight of rice by 12.58%（P<0.05）.At 30 days after Mg application,leaf dry weight ratio increased by 0.70 percentage points on average compared with Mg0.The dry weight of Mg3 was 3.76%lower than that of Mg0 and11.11%lower than that of Mg1（P<0.05）.At maturity stage,ear dry weight in 2019 increased by13.82%on average compared with Mg0（P<0.05）.Compared with Mg1,Mg3 increased by 130.99%（P<0.05）and 11.72 percentage points（P<0.05）,respectively.Compared with Mg0 and Mg1,the contribution rate of matter transport in stem and leaf increased by 7.62 and 10.82 percentage points（P<0.05）,respectively.Compared with Mg0 and Mg3,Mg2 treatment increased substance assimilation by 10.66%and 34.68%（P<0.05）,respectively.3.Applying Mg to the leaves can prevent the premature senescence of rice leaves.At 10 days after leaf Mg application,leaf leaf rate of rice increased by 6.10 percentage points on average（P<0.05）;Compared with Mg0,Mg1 and Mg2 treatments increased soluble protein content by 60.17%（P<0.05）and 73.39%（P<0.05）,respectively,but had no significant effect on malondialdehyde content.Compared with Mg0,Mg3 treatment increased the content of malondialdehyde by 52.11%（P<0.05）.At 30 days after Mg application,the content of malondialdehyde（MDA）was significantly increased and the content of soluble protein was decreased,but the percentage of green leaves was not significantly affected.4.Folial Mg application can increase rice yield and improve rice quality.Compared with Mg0,leaf Mg application increased rice yield by 9.80%（P<0.05）in 2019.Mg2 treatment had the highest yield increase（13.64%）（P<0.05）.There was no significant difference in yield between treatments in 2020.Correlation analysis showed that there was a parabolic relationship between rice yield and leaf Mg application concentration.With the increase of Mg application,rice yield increased,but with the high Mg application concentration,rice yield decreased,and the highest Mg application concentration was 10.22%.The increase of grain yield by folial Mg application was mainly achieved by increasing 1000-grain weight and seed setting rate.In addition,folial Mg application could improve milled rice rate,which increased by 6.85 percentage points and 6.75 percentage points on average compared with Mg0 in 2019 and 2020,respectively（P<0.05）.However,folial Mg application had no significant effects on brown rice rate,protein content and eating value.