利用小麦三叶期毒害效应指标表征成熟期籽实产量Ni毒害的探讨

为探明小麦三叶期幼苗和成熟期籽实产量的Ni毒害效应及其相互关系,实现小麦作物Ni毒害的早期诊断,以春小麦"冀张春3号"为材料,采用盆栽试验方法,研究了外源Ni对小麦三叶期幼苗生长发育和成熟期籽实产量的影响,并对小麦三叶期和成熟期的生理指标进行相关分析.结果表明,外源Ni投加量100 mg·kg~(-1),茎叶干质量和籽实产量无明显下降(p0.05),茎叶中可溶性糖含量(p0.05)和硝酸盐含量(p0.01)增加,茎叶干鲜比值增加;Ni投加量≥100 mg·kg~(-1),茎叶干质量、可溶性糖、硝酸盐含量和成熟期籽实产量均明显下降(p0.05或p0.01),茎叶中淀粉和抗坏血酸含量明显增加(p0.05或p0.01),茎叶干鲜比值下降.土壤中各形态Ni与小麦三叶期幼苗中Ni呈显著正相关(p0.01),土壤和幼苗中Ni与茎叶干质量、可溶性糖和籽实产量均呈显著负相关(p0.05或p0.01),表明小麦三叶期幼苗毒害和成熟期籽实产量下降是由作物体内Ni毒害造成的且无观察效应浓度(NOEC)一致;同时试验观察到小麦三叶期幼苗茎叶干质量、可溶性糖和硝酸盐含量变化与成熟期籽实产量呈显著正相关关系(p0.05或p0.01),表明利用小麦三叶期幼苗Ni毒害效应指标表征成熟期籽实产量Ni毒害是可行的.试验确定外源Ni对小麦成熟期籽实产量的无观察效应浓度为:土壤全Ni含量为139.08 mg·kg~(-1),土壤有效态Ni(DTPA提取)含量为21.59 mg·kg~(-1),小麦茎叶Ni含量为15.37 mg·kg~(-1),小麦根系Ni含量为361.78 mg·kg~(-1).

Characterization of the toxic effects of exogenous Ni on yield at maturity via seedling toxicity indexes at three-leaf stage in wheat(Triticum aestivum L.)

The objective of this paper was to explore the relationship between the toxic effects of Ni at three-leaf stage and yield at maturity in spring wheat. Spring wheat cultivar Jizhangchun-3 was used in a pot experiment to reveal the effects of exogenous Ni on wheat seedling growth at three-leaf stage and yield at maturity. Physiological indexes of these two stages were also studied. The results showed that less than 100 mg·kg^-1exogenous Ni did not reduce the stem and leaf dry weight and the yield significantly (p>0.05), whereas the contents of both soluble sugar (p>0.05) and nitrate (p<0.01) as well as the ratio of dry weight to fresh weight increased. When exogenous Ni exceeded 100 mg·kg^-1, stem and leaf dry weight, soluble sugar content, nitrate content, and the yield decreased (p<0.05 or p<0.01). However, starch and ascorbic acid content increased (p<0.05 or p<0.01), and the ratio of dry weight to fresh weight decreased. Correlation analysis indicated that there was a significantly positive correlation between Ni content in soil and Ni content in wheat seedlings (p<0.01). However, Ni content both in soil and in wheat seedlings had a significantly negative correlation with stem and leaf dry weight, soluble sugar content, and yield (p<0.05 or p<0.01). These results indicated that the negative effects on wheat seedlings and decreased yield at maturity were caused by the toxic effects of Ni, and the no observed effect concentration (NOEC) was the same for both seedling effects and yield. Most importantly, stem and leaf dry weight, soluble sugar content, and nitrate content at three-leaf stage all displayed a significantly positive correlation with the yield at maturity stage (p<0.05 or p<0.01). It may be feasible for the toxicity indexes at three-leaf stage to characterize Ni toxicity on yield at maturity stage. It was determined that the NOEC of 139.08 mg·kg^-1 total Ni in soil, 21.59 mg·kg^-1 available Ni in soil (DTPA extraction), 15.37 mg·kg^-1 Ni in both stems and leaves, or 361.78 mg·kg^-1 Ni in roots, respectively.