宁夏引黄灌区盐碱富硒土壤对水稻硒元素吸收积累的影响

Effects of Salinity and Alkalinity of Selenium-rich Soils in Yellow River Irrigation Area of Ningxia on Selenium Absorption and Quality of Rice

【目的】探明不同类型盐碱富硒土壤对水稻硒的吸收、转运积累的影响。【方法】以耐盐碱水稻宁粳45号为试验材料,设置3种不同类型盐碱富硒土壤:A处理(轻度盐化土壤)、B处理(轻度碱化土壤)、C处理(中重度碱化土壤),测定水稻各生育时期(苗期、拔节期、抽穗期、灌浆期、成熟期)根、茎、叶、籽粒、麸皮的硒含量。【结果】(1)水稻根、茎、叶和籽粒中的硒含量均表现为:C处理>B处理>A处理。成熟期硒含量高低呈现根系>茎>叶>籽粒的特点。成熟期籽粒均达到富硒标准,分别为0.17 mg·kg^(-1)(A)、0.22 mg·kg^(-1)(B)和0.24 mg·kg^(-1)(C),且C处理显著高于A、B处理(P<0.05);(2)不同生育期,水稻各器官中硒含量及累积量不同,各器官累积量均表现为:C处理>B处理>A处理。水稻硒的生物富集高峰期在抽穗期,成熟期水稻各器官硒的累积量表现为精米>茎>叶>根>颖壳;(3)整个生育时期硒有一定的运转规律:苗期到抽穗期,硒由根向茎、叶中转移,抽穗期到成熟期穗中硒含量主要来自于茎叶的供给。(4)根系硒的吸收系数和初级转运系数随着盐碱程度加重而增加,表现为C处理>B处理>A处理,而次级转移系数随着盐碱程度加重而降低,表现为A处理>B处理>C处理。【结论】在pH为8.41~9.51、全盐含量为1.74~3.62 g·kg^(-1)、全硒含量为0.23 mg·kg^(-1)的盐碱富硒土壤上能生产出符合富硒标准水稻,且中重度盐碱土壤能促进水稻对硒的吸收转运及积累,为盐碱富硒土壤开发富硒水稻提供理论支撑和依据。

【Objective】Effects of different types of saline-alkali soil that are selenium(Se)-rich on the absorption,transport,and accumulation of Se in rice grown on them were studied.【Method】Saline-alkali-tolerant Ningjing 45 seedlings were grown on soils in the Yellow River irrigation area of Ningxia province that were mildly saline(Treatment A),mildly alkaline(Treatment B),and moderate-severely alkaline(Treatment C).Se uptake,accumulation,and quality of the seedlings grown on the pots were determined.【Result】(1)The Se contents in the roots,stems,leaves,and grains of the rice plants ranked as Treatment C>Treatment B>Treatment A,and at maturity,roots>stems>leaves>grains.The contents in mature grains were 0.17 mg·kg^(-1)under Treatment A,0.217 mg·kg^(-1)under Treatment B,and 0.24 mg·kg^(-1)under Treatment C.They all met the enrichment standard set for rice;however,Treatment C produced a significantly higher level of the metal element in the plants than the other two treatments(P<0.05).(2)The Se accumulation in rice peaked at heading stage but varied in the organs at maturity with the ranking of milled rice>stems>leaves>roots>glume.(3)In seedling to heading stage,Se transported basically from the roots to the stems and leaves,but in heading to maturity,mainly from the stems and leaves to the spikes.(4)The Se absorption and primary transport coefficients of the roots increased with increasing salinity and alkalinity in soil.Thus,the effect was the greatest under Treatment C,followed by Treatment B and Treatment A.In contrast,the secondary transfer coefficient decreased with the increases to reverse the ranking order.【Conclusion】It appeared that Se-enrichment for rice grown on a saline-alkali soil that had an ample supply of the metal element could be realized if the soil had a pH ranging between 8.41 and 9.51,salt content between 1.74 g·kg^(-1)and 3.62 g·kg^(-1),and Se content of 0.23 mg·kg^(-1).And,interestingly,moderate and heavy saline-alkali soils bolstered the absorption,transport,and accumulation of Se in rice,and therefore,the normally considered undesirable conditions would enhance,rather than hinder,the use of like land masses.