Effects Of Salty Water Irrigation With Different Concentrations On Rice Yield,Leaf Physiological Characteristics And Grain Quality

In order to clarify the effect and mechanism of different concentrations of salty water irrigation on rice growth,leaf physiological characteristics and yield,grain quality formation The experiment was carried out in Yangzhou University Agricultural College Experimental Farm(32.39°N,119.42°E)from 2018 to 2019.The late maturing mid japonica rice varieties Nanjing9108 and Yandao 12 were used as test materials,which were planted in large areas in Jiangsu Province.Split plot design was adopted in this study,salt treatment as the main plot.the variety was the split zone,comparing the effect of different concentrations of salty water(0%,0.10%,0.15%,0.20%.0.25%,0.30%.0.35%)irrigation on rice yield,morphological structure,leaf physiological characteristics and quality of rice.The main results are as follows:1.Salt stress decreased the growth and bioaccumulation of Nanjing 9108 and Yandao 12.The plant height,tiller number,leaf area index,length and width of inverted leaf,number of green leaves,fresh weight and dry weight of stem and leaf decreased with the increase of salt concentration.At the same time,the study also found that under 0.35%salt concentration,the index value of Yandao 12 was slightly better than that of Nanjing 9108.With the increase of salt concentration,the nitrogen content of stems,leaves and ears(heading and maturity)decreased in different periods,indicating that salt inhibited the absorption and transportation of nitrogen by the two varieties.2.Salt stress significantly reduced the yield of rice.In 2018 and 2019,the yield trend is the same,with the increase of salt concentration,the yield is significantly reduced.According to the analysis of yield forming factors,salt stress had little effect on seed setting rate,which reached a significant level under 0.35%salt concentration,the ear length,ear number,grain number per ear and 1000 grain weight decreased with the increase of salt concentration.The number of primary and secondary branches of Nanjing 9108 decreased with the increase of salt concentration,and the number of primary and secondary branches of yandao 12 was higher under 0.10%salt concentration than that of the control and then decreased with the increase of salt concentration3.The chlorophyll content of the flag leaves of Nanjing 9108 and Yandao 12 decreased with the increase of salt concentration.Net photo synthetic rate(Pn),stomatal conductance(Gs).transpiration rate(Tr)and apparent mesophyll conductance(AMC)decreased with the increase of salt concentration;water use efficiency(WUE)decreased with increase of salt concentration and significantly different from the control when the salt concentration was more than 0.20%;intercellular CO2 concentration(Ci)decreased first and then increased with the increase of salt concentration,indicated that with increasing salt concentration,the cause of the decrease in leaf photosynthetic rate shifted from stomatal restriction to non-stomatal restriction.Potential activity(Fv/Fo),maximum photochemical quantum yield(Fv/Fm),photochemical quenching coefficient(qP)and non photochemical quenching coefficient(qN)of PSⅡ decreased with the increase of salt concentration4.Salt stress makes rice to alleviate its damage by increasing osmotic regulators.The content of proline in the leaves of Nanjing 9108 and Yandao 12 at jointing and heading stage,under 0.10%salt concentration was little difference with the control,after that,with the increase of salt concentration,it increases significantlythe.Under 0.35%salt concentration,the content of prolinein the leave of Nanjing 9108 was higher than that of Yandao 12.The content of total soluble sugar and sucrose of leaf increased with the increase of salt concentration at tillering stage,jointing stage and heading stage,but the maturity decreased with the increase of salt concentration,it may be that salt in mature stage accelerates leaf senescence and death,so it can not produce more osmoregulation substances.5.Compared with control,the amylose content of rice decreased significantly under the low salt concentration(0.10%-0.15%),while the brown rice rate,precision rice rate and whole rice rate increased,at the same time,the peak viscosity,hot pulp viscosity and final viscosity of RVA increased.The appearance,viscosity,balance degree and taste value of rice under 0.10%salt concentration were higher than those of the control,and the gel consistency of Nanjing 9108 and Yandao 12 was greater than that of the control(4.5 mm and 3.5 mm,respectively)under 0.10%salt concentration.Under the medium and high salt concentration(0.20%-0.35%),the processing quality,cooking taste quality and starch viscosity of rice(RVA)decreased significantly.The chalkiness rate and chalkiness degree of rice decreased with the increase of salt concentration.In conclusion,the quality of rice was improved under the low salt concentration(0.10%-0.15%),and the quality of rice was deteriorated under the high salt concentration(0.35%).