| Soil salinization seriously restricts agricultural production,and also hinders regional ecological restoration and sustainable development.However,as a resource,saline soil plays an important role in the development of high-quality agriculture.Selenium is an essential micronutrient for human and animals.The development and utilization of selenium-rich agricultural products is one of the development directions of high-quality agriculture.About one-third of cultivated land in Yinbei irrigation area of Ningxia shows different degrees of salinization.The latest geological survey data show that the distribution of selenium-rich soil and saline soil in Yinbei irrigation area is highly coincident.Previous studies have found that selenium is more effective in saline-alkali soil.How to effectively utilize saline-alkali selenium-rich soil resources in Ningxia irrigation area is of great significance to the high-quality development of local agriculture.Therefore,in this study,three different types of saline-alkali selenium-rich soils were selected in Yinbei area,and the effects of saline-alkali selenium-rich soils on selenium absorption,accumulation and quality of rice were studied by combining field and pot experiments.The relationship between physical and chemical properties of saline-alkali soil and available selenium content was explored,and the changes of selenium absorption,transportation and accumulation of different saline-alkali tolerant rice were clarified.The relationship between selenium absorption,accumulation and quality of rice was analyzed,and rice varieties suitable for planting in different types of saline-alkali selenium-rich soils in Yinbei irrigation area of Ningxia were screened out.The main results are as follows:(1)The study found that available selenium in different types of saline-alkali selenium-rich soil was significantly positively correlated with pH and available potassium,and was significantly positively correlated with total salt content,organic matter and available phosphorus.Regression analysis of soil available selenium content with total salt content,organic matter content,pH,available potassium content and available phosphorus content showed that soil available selenium content increased with the increase of pH and available potassium content.When the total salt content was less than 2.25 g·kg-1,the effective selenium content showed a downward trend with the increase of total salt content,while when the total salt content was greater than 2.25 g·kg-1,it was opposite;when the organic matter content was less than 9.5 mg·kg-1,the change trend of organic matter and effective selenium content was opposite.When the organic matter content was more than 9.5 mg·kg-1,the change trend of effective selenium content was the same as that of organic matter,and the effective selenium content increased with the increase of organic matter.When the available phosphorus content was less than 19 mg·kg-1,the soil available selenium showed an upward trend,and when the available phosphorus content was more than 19 mg·kg-1,the available selenium showed a downward trend.(2)The variation trends of selenium absorption and accumulation in different organs of rice at different growth stages were different.The selenium content in rice roots increased first and then decreased,reaching the maximum concentration at heading stage,the minimum concentration at filling stage,and slightly increased at maturity stage.The selenium content in rice stems was the highest at seedling stage,and decreased with the growth period,with the lowest concentration at mature stage.The selenium content in rice grains showed an upward trend,and the selenium content in mature grains was the largest.Selenium content in mature rice showed root>leaf>stem>grain.The accumulation of selenium in the whole plant of rice reached the highest at heading stage.During the whole growth period,selenium has a certain operation rule:from seedling stage to heading stage,selenium transfers from root to stem and leaf,and from heading stage to maturity,selenium content in spike mainly comes from the supply of stem and leaf.(3)There were differences in Se uptake and transport among rice varieties in different types of saline-alkali Se-rich soils.The absorption coefficient and primary transport coefficient of selenium in roots increased with the increase of salinity and alkalinity,which was shown as C treatment(moderate to severe alkaline soil)>B treatment(mild alkaline soil)>A treatment(mild saline soil),while the secondary transfer coefficient decreased with the increase of salinity and alkalinity.The secondary transport coefficients of A,B and C were the highest in Haijing 14.The grain selenium content at maturity stage of each test site reached the selenium-enriched rice standard,and the selenium content of Ningjing 52 was the highest,which was 0.30 mg·kg-1(A treatment),0.32 mg·kg-1(B treatment)and 0.34 mg·kg-1(C treatment),respectively.The selenium accumulation of Ningjing 45(0.41 μg/plant)was the highest in A test point,and that of Ningjing 52(0.53 μg/plant and 0.45 μg/plant)in B and C test points.(4)The selenium content of different saline-alkali selenium-rich soil content showed and negative correlation with brown rice rate,refined rice rate,taste value and glue consistency.The correlation coefficient was ranked as:chalkiness>refined rice rate>chalkiness ratio>brown rice rate>glue consistency>taste value>protein content>amylose content>finishing rice ratio>aspect ratio.Regression analysis of grain selenium content and chalk grain rate,chalk,brown rice rate,rice rate,taste value,protein content,amylose content and glue consistency,found that in the salt soil,alkali soil and rice grain selenium content,chalk grain content,chalk content,protein content are rising trend,and brown rice rate,rice rate,taste value and consistency.Among them,the amylose content increased with the increase of grain selenium content,and the amylose content decreased when the grain selenium content is greater than 15 μg· kg-1.(5)Ningjing 45 was planted on mild salinized soil(total selenium 0.233 mg · kg-1,pH 8.21～8.41,total salt 2.18～2.86 g·kg-1)and moderate to severe alkaline soil(total selenium 0.233 mg·kg-1,pH 9.27～9.51,total salt 2.57～3.62 g·kg-1)by fuzzy similarity priority ratio analysis.Fuyuan No.4 was most suitable for planting in mild alkaline soil(total selenium 0.233 mg·kg-1,pH 9.27～9.5 1,total salt 1.76～2.18 g·kg-1). |
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