The field experiments were conducted to explore the changes in metabolism related to leaf senescence in proso millet (Panicum miliaceum L.) under proso millet/mung bean intercropping system. Results showed that intercropping increased leaf photosynthesis, as measured by the increased net photosynthetic rate and chlorophyll content, maximum photochemical efficiency of PSII, and decreased nonphotochemical quenching coefficient. These responses resulted in the increased leaf number and area and reduced yellowing leaf rate; leaf photosynthetic capacity was maintained for longer periods. Such improvements occurred due to enhanced activities of protective enzymes (superoxide dismutase, catalase, peroxidase) and lowered malondialdehyde and superoxide radical contents. This conclusion was supported by the increased N metabolism in leaves. The grain yield was stimulated by 6.8-37.3% compared to the sole system. Intercropping patterns would delay proso millet leaf senescence and increase grain yield in this region.

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Soil waterlogging is one of the most serious abiotic stresses on plant growth and crop productivity. In this study, two potassium application levels (0 and 150 kg K2O hm−2) with three types of soil waterlogging treatments (0 d, 3 d and 6 d) were established during cotton flowering and boll-forming stages. The results showed that soil waterlogging markedly reduced RWC (relative water content), gas exchange parameters and cotton biomass. However, potassium application considerably improved the aforementioned parameters. Specifically, 3 d soil waterlogging with potassium increased Pn (net photosynthetic rate), Gs (stomatal conductance), Ci (intercellular CO2 concentration) and Tr (transpiration rate) by 4.55%, 27.27%, 5.74% and 3.82%, respectively, compared with 3 d soil waterlogging under no potassium, while the abscission rate reduced by 2.96%. Additionally, the number of bolls and fruit nodes under 6 d soil waterlogging with potassium increased by 16.17% and 4.38%, compared with 6 d soil waterlogging under no potassium. Therefore, it was concluded that regardless of 3 d or 6 d soil waterlogging, potassium application alleviated the negative effects of waterlogging by regulating the plant water status, photosynthetic capacity and plant growth in cotton. These results are expected to provide theoretical references and practical applications for cotton production to mitigate the damage of soil waterlogging.

Heterogeneity is widespread in natural environments; as a result, connected clonal ramets often live in areas characterized by patches of different resources. Specifically, clonal plants are frequently affected by conditions of heterogeneous water stress. This raises the question of how clonal plants grow and reproduce in areas with patches of different resources. In this study, we investigated the adaptation mechanisms of clonal plants under heterogeneous environmental conditions. On the one hand, we bore in mind that phenotypic plasticity is abundantly exhibited in clonal plants. Clonal plants respond to water stress mainly through regulation of the size of individuals, the allocation of population biomass, and the number of daughter plants, as well as the extension ability and branching intensity of clonal organs, which directly affect reproduction and population stability in clonal plants. On the other hand, we also considered the physiological integration in clonal plants which has been shown in many studies. Ramets of clonal plants normally stay connected to each other through horizontal connectors (stolons or rhizomes). Communicated substances and resources such as water, mineral nutrition, photosynthetic products, and secondary metabolites are translocated between ramets; by such means, the plant relieves stress caused by heterogeneous patches. In this study, we sought to obtain scientific references to improve our understanding of how clonal plants in natural environments acclimate to stresses caused by soil heterogeneity.

Background and aims Intercropping of hyperaccumulators with commercial crops is widely accepted in single-metal-polluted farmland. However, the ecological risks of non-hyperaccumulated metals in intercropping systems have not been revealed. Methods To evaluate Pb and Cu activation and absorption in an intercropped system of Sedum alfredii and Cicer arietinum L., sequential extraction and dissolved organic matter (DOM) characterization were used to describe the migration of metals in the intercropping system. Results This study found that the concentrations of DOM in the S. alfredii monoculture and intercropping system were significantly higher than those in the C. arietinum L. monoculture, and DOM from the former two cultivation strategies had significantly higher Cd, Pb, and Cu extraction capacity than those from the latter. Compared with the C. arietinum L. monoculture, C. arietinum L. intercropping had significantly lower Cd content owing to the depletion of Cd by S. alfredii. However, Cu and Pb concentrations in the former were significantly higher than those in the latter because S. alfredii mobilized these metals but did not hyperaccumulate them. Conclusion The results indicated that intercropping efficiently decreased the potential risk of Cd, but deteriorated the ecological risk of Pb and Cu. Therefore, intercropping does not present a suitable land-use pattern for multi-metal-polluted soil.