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Molybdenum (Mo) adsorption by acidic yellow-brown soil was investigated as a function of a pH (1–13) and the equilibrium of P solution (0, 3.1, and 31 mg L−1) concentration. Mo adsorption by acidic yellow-brown soil increased within the pH range from 1 to 4. Above pH 4, Mo adsorption decreases with an increase in pH. The maximum adsorption was found between pH 2 and 4. Competitive adsorption experiments showed that the equilibrium sorption data fitted into Langmuir and Freundlich isotherms. The sorption data of Mo on the acidic yellow-brown soil fitted well with the Langmuir isotherm model due to the higher R2 value. A reduction in Mo adsorption by the acidic yellow-brown soil was noticed at higher addition levels of P (3.1 and 31 mg L−1). Therefore, P increasing the bioavailability of Mo and enhancing Mo uptake by plants might be related to the inhibition of Mo absorption by the acidic yellow-brown soil.

Molybdenum (Mo) is an essential element for higher plants. Recent research indicated that Mo application enhanced cold-resistance of winter wheat. In order to improve our understanding of the mechanisms of cold resistance enhanced by molybdenum application in winter wheat, liquid nutrient culture experiments were conducted to investigate the effects of molybdenum on endogenesis hormone in winter wheat (Mo efficient cv. 97003 and Mo inefficient cv. 97014) under low temperature stress. The results showed that Mo application increased the AO activities, the contents of abscisic acid (ABA) and indole-3-acetic acid (IAA) in the leaves of +Mo winter wheat under low temperature stress. No significant difference in the contents of GA3 and Z was detected between -Mo and +Mo winter wheat at the earlier stage of low temperature stress, whereas the contents of gibberellin (GA3) increased significantly, and zeatin (Z) decreased significantly in the leaves of +Mo winter wheat at the later stage of low temperature stress. Mo-deficiency also induced the drastic decrease of the ABA/GA in the leaves of winter wheat under low temperature stress. These results indicated that Mo regulated the ABA and IAA biosynthesis via AO in winter wheat and the response of ABA and IAA to Mo deficiency was prior to that of GA3 and ZT. The dramatic decrease in ABA and IAA levels in Mo deficient winter wheat may affect the homeostasis of endogenous hormones and Mo regulated cold resistance via the levels and balance of endogenous hormone in winter wheat.

In order to explore the effects of combined application on selenium (Se) and phosphorus (P) fertilizer on selenium uptake, translocation and organic selenium species in grains of winter wheat, a wheat cultivar' Zhengmai 379' was chosen as the test material. A pot experiment with 3 P levels of 0(P0), 80(P80), 160 mg⋅kg-1 (P160) and 2 Se levels of 0(Se0), 1 mg⋅kg-1 (Se1) were set . A total of 6 treatments (P0Se0, P80Se0, P160Se0, P0Se1, P80Se1, P160Se1, respectively) were used to analyze the yield, P and Se concentration, accumulation in each part of winter wheat, transport coefficient and Se species in grain. The results showed that the yield of winter wheat was significantly increased by the combination application of P and Se, and the highest yield of winter wheat was 46.25 g⋅pot-1 under P80Se1 treatment. Se application could significantly reduce the P content and accumulation of each part of the winter wheat, but increase the P migration coefficient of glume to grains under P80 and P160 treatments. Each part of the winter wheat had high Se concentration under P0Se1 treatment. P application reduced the Se concentration of each part of the winter wheat and the Se migration coefficient of root to stem leaf, but increased Se accumulation in grains as well as in whole plant. Besides grain, each tissue as well as in whole plant had high Se accumulation under P80Se1 treatment. Se application increased the Se migration coefficient of glume to grain and the proportion of total Se accumulated in the grains and roots of winter wheat under P80 and P160 treatment, but decreased the ratio of total Se accumulated in glumes. The analysis on selenium species showed that Se application increased the organic Se concentration in the grains, Se in winter wheat grains was mainly in the organic form including selenocystine and selenomethionine. Selenomethionine and inorganic Se concentration in grains decreased with the increasing P application. Therefore, appropriate P combined with Se application enhanced grain yield of winter wheat, promoting the transfer of selenium in the winter wheat to the grain, increased Se accumulation and organic Se concentration of grain under P80Se1 treatment. The results provided guidance for rational application of phosphorus fertilizer and selenium fertilizer in selenium-enriched wheat production. [ABSTRACT FROM AUTHOR]

Objective Soil contamination by cadmium (Cd) and lead (Pb) is a great environmental concern for food safety, and breeding cultivars that can reduce their uptake is one way to grow crops in Cd-and Pb-contaminated soils. In this paper, we experimentally studied how wheat lines with different phosphorus (P) uptake affect their uptake, translocation and accumulation of P, Cd and Pb in the crops. Method The experiment consisted of a lab part and a field part. The lab part considered one factor -- wheat varieties, and the field part was arranged randomly in soil that had been moderately contaminated by Cd and Pb. In both parts, we measured Cd and Pb uptake and their subsequent translocation. Result The average P content in the roots of lines with high P (HP) use efficiency was 7.69 mg/g, significantly lower than that in the lines with low P (LP) use efficiency, which was 8.36 mg/g (P<0.05). The average P content in the shoots of HP varieties was 9.73 mg/g, significantly higher than the 8.19 mg/g in the LP cultivars (P<0.05). The transport coefficient of P in HP varieties was 1.45, significantly higher than the 1.19 of the LP varieties (P<0.05). The kinetic uptake of Cd and Pb by roots and their translocation to shoots followed Michaelis- Menten equation (R2>0.94), with the maximum absorption rates (Vmax) and the Michaelis constants (Km) differing significantly between varieties (P<0.05). The Vmax of the roots of HP varieties was 23.9 and 411 μg/(g·d), respectively, for Cd and Pb, in comparison with 80.0 and 835 μg/(g·d) (P<0.01) for the LP lines. In contrast, Vmax for Cd and Pb in the shoots of the HP varieties was much higher than that for the LP varieties. The difference in Km between the HP and LP varieties was consistent with their difference in Vmax. Correlation analysis showed that the transport coefficients of both Cd and Pb were negatively correlated with root P content (r=-0.638 and -0.714, respectively) at significant level. The transport coefficient of Cd was positively correlated with P transport coefficient (r=0.671, P<0.01). The Pb transport coefficient was also positively correlated with P transport coefficient though not at significant level (r=0.391, P>0.05). The increase in root P content helps reduce the translocation of Cd and Pb; an increase in translocation coefficient of P did not show a noticeable impact on Pb translocation, but significantly boosted Cd transport from roots to the shoots. Conclusion The roots of LP varieties showed high uptake but low translocation of P, Cd and Pb, as opposed the HP varieties which showed a low uptake but high translocation. This suggests that LP varieties are more suitable for growing in soils contaminated by Cd and/or Pb. [ABSTRACT FROM AUTHOR]