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Corn-peanut intercropping is an important element of China's agricultural planting model as it confers ecological benefits and increases yield. The aim of this study was to explore the productivity differences between intercropping and monoculture by using the 13C isotope tracer labelling method. Corn hybrid Denghai 618 (DH618) and peanut variety Huayu 22 (HY22) were used as test materials under three planting methods, single corn, SM; single peanut, SP; and corn-peanut intercropping, IM and IP, respectively, during two growing seasons. The results showed that IM increased yield by 59.7% and 62.3% compared with SM, respectively. IP reduced yield by 31.3% and 32.3% compared with SP, respectively. IM significantly increased the photosynthetic rate, leaf area, 13C assimilation distribution, and dry matter accumulation of summer corn, which led to an increase in the kernel number and grain yield. The decrease in intercropped peanut yield was mainly caused by a decrease in the full-pod rate and number of pods per plant. The decrease in peanut yield did not affect the production of intercropping benefit due to the larger intercropping advantage and land equivalence ratio. Corn-peanut intercropping yielded greater economic benefits than monoculture. These results showed the utility of the peanut-corn intercropping model. [ABSTRACT FROM AUTHOR]

Aims: To realize the so-called "Second Green Revolution", it is imperative to study the roots of crop plants, and identify those traits that improve the efficiency of nitrogen (N) acquisition. We aimed to evaluate how the N acquisition efficiency of six hybrid maize lines commonly grown in northern China depends on their root anatomy. Methods: Maize hybrids classified as having high nitrogen uptake efficiency (HNUE) and low nitrogen uptake efficiency (LNUE) were grown under high-N and low-N conditions in the greenhouse and the field. Results: Under N stress in the field and the greenhouse, HNUE increased shoot dry weight, root length density, N content and nitrogen use efficiency compared to LNUE. Low N availability increased the percentage of root cortical aerenchyma and the size of cortical cells. Root anatomy, with greater formation of root cortical aerenchyma and larger cortical cell size, was associated with increased specific nitrogen absorption efficiency (SNAE) and shoot biomass under N stress. Under low N availability, the percentage of aerenchyma and their total area had significant positive correlations with the shoot dry weight, total N uptake, SNAE. Conclusions: The results suggest that plants in limited N availability form more root cortical aerenchyma and have larger cortical cells, which is of benefit to root growth, soil exploration, N acquisition, and shoot biomass. These observations support the hypothesis that root anatomical phenotypes that affect the metabolic and construction costs of producing root length merit consideration as selection criteria for breeding to improve N acquisition in hybrid maize. [ABSTRACT FROM AUTHOR]

In the Huang-Huai-Hai region of China, continuous rain is the main meteorological constraint for summer maize, accompanied by stresses of both waterlogging and shading. To evaluate the independent and combined effects of shading and waterlogging on summer maize at different stages, a field experiment was performed to study the grain yield, crop growth, and canopy functionality of summer maize in response to waterlogging (W), shading (S), and their interaction for a 6 day period starting at the third leaf stage (V3), the sixth leaf stage (V6), and the tasseling stage (VT). Shading, waterlogging, and their combination stress (S+W) significantly decreased the grain yield of summer maize. Among these, the simultaneous stress induced greater yield losses than single stresses at any growth stage. The reduction of yield induced by waterlogging at early and late stages differed from 20–40 % to 3–16 %. Shading at VT stage induced most serious losses of grain yield. The grain yield of summer maize was closely related with the crop biomass accumulation. Shading, waterlogging, and their combination stress significantly decreased leaf area index resulting in serious reduction of the radiation interception. Besides, the leaf SPAD value and photosynthetic rate were also significantly reduced by the stresses, which led to notable reduction in radiation use efficiency (RUE) of summer maize. Thereby, the total accumulated crop biomass was decreased. Moreover, the biomass partitioning to ears was decreased. Accordingly, the 1000-kernel weight and kernels per ear were decreased by the stresses, leading to yield losses. This study explored the differential responses of radiation interception, canopy functionality, and RUE to waterlogging, shading, and their combined stress at different growth stage, furthering our understanding on the yield and growth for summer maize crops under persistent rainfall conditions. • The response of yield components to combined stress at different stage was differed. • Waterlogging at early stage reduced radiation interception and RUE decreasing yield. • Shading at VT lowered incident radiation, decreased kernel setting reducing the yield. • The combined effects of shading and waterlogging on grain yield was greater than single stress. [ABSTRACT FROM AUTHOR]