In order to study the effect of foliar DA-6 on the phosphorus and potassium content of tomato seedlings under cadmium stress, the pot experiment was used to cultivate ‘Zhongza 9’ tomato in 50 μmol/L CdCl2•2.5H2O nutrient solution. The effects of DA-6 at different concentrations (0, 10, 20, 30 and 40 mg/L) on the phosphorus and potassium uptakes of tomato seedlings under cadmium stress were studied. The results showed that when the DA-6 concentration was 20 mg/L, the phosphorus content in the root and stem of tomato seedlings increased significantly, which were 41.5% and 12.8% higher than the control. In all treatments, when the DA-6 concentration was 10 mg/L, the potassium content of tomato seedling roots, stems and shoots increased significantly, which were 25.4%, 10.0%, and 5.8% higher than the control. In summary, the low-concentration DA-6 treatment had a certain effect on increasing the phosphorus and potassium content of tomato, and there were differences in the optimal concentration of phosphorus and potassium content.

To study the effects of the reciprocal grafting on the photosynthesis of two genotypes tomato offspring under selenium stress, red ball cherry tomato cherry 5-5-1 and yellow ball cherry tomato yellow RTY-3-2 post-grafting generation (red scion, red rootstock, yellow scion and yellow rootstock) and seedlings (red CK and yellow CK) planted in 10 mg·kg-1 selenium soil, and the pot experiment was carried out to study the effects of the reciprocal grafting on the growth characteristics and the photosynthesis of tomato offspring under selenium stress. The results showed that grafting increased the fresh weight of the organs of the offspring, the ratio of root to shoot, and the functional activity of the roots of the plants, which was conducive to the growth of tomato offspring. Simultaneously, it could effectively improve the photosynthetic capacity of grafted offspring leaves at the seedling stage. The grafted offspring of rootstocks had the best effect on improving the net photosynthetic rate, stomatal conductance and transpiration rate and stomatal conductance of tomato leaves, and decreased intercellular CO2 concentration. Among them, the best effect of yellow rootstock was to provide ideas and theoretical basis for the production of selenium-enriched tomatoes in the selenium-deficient areas in the future.

Effects of Cyphomandra betacea seedlings intercropping with F1 generations of Solanum photeinocarpum on soil enzyme activity under cadmium (Cd) stress were studied. The activities of soil catalase, soil polyphenol oxidase, soil sucrase, and soil urease were measured. The results showed that under Cd stress, C. betacea seedlings intercropping with F1 generation of S. photeinocarpum increased soil polyphenol oxidase and decreased soil catalase activities. C. betacea seedlings intercropping S. photeinocarpum of mine ecotype and two F1 generations of S. photeinocarpum enhanced soil sucrase activity. C. betacea seedlings intercropping two ecotypes F1 generations of S. photeinocarpum enhanced soil urease activity.