The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast China. Twenty-one hybrids were grown for 2years in Northeast China at densities of 30,000, 52,500, 75,000, and 97,500plantsha−1 and N application levels of 0, 150, 300, and 450kgNha−1. Irrespective of density or nitrogen application rate, grain yields both per plant and per unit area were significantly higher for newer than older hybrids. As plant density increased from 30,000 to 97,500plantha−1, yield per plant of 1970s, 1980s, 1990s, and 2000s hybrids decreased by 50%, 45%, 46%, and 52%, respectively. The response of grain yield per unit area to plant density was curvilinear. The estimated optimum plant densities were about 58,000, 49,000, 65,000, and 65,000plantsha−1 for hybrids released in the 1970s, 1980s, 1990s, and 2000s, respectively. The theoretical optimum densities for the hybrids released from the 1970s to the 2000s increased by 1750plantsha−1 decade−1. Nitrogen fertilization significantly increased grain yields per plant and per unit area for all hybrids. The theoretical optimum N application rates for high yield for hybrids released in the 1970s and 1980s were about 280 and 360kgha−1, and the hybrids from the 1990s and 2000s showed highest yield at 330kgha−1N. No significant difference in the grain yields of 2000s hybrids between the N levels of 150 to 450kgha−1 was found. Significant yield gains per plant and per unit area were found, with average increases of 17.9g plant−1 decade−1 and 936kgha−1 decade−1 over the period 1970–2010, respectively. Yield gains were attributed mainly to increased yield per plant, contributed by increases in kernel number per ear and 1000-kernel weight. The rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones, especially at high plant density

De-etiolation consists of a series of developmental and physiological changes that a plant undergoes in response to light. During this process light, an important environmental signal, triggers the inhibition of mesocotyl elongation and the production of photosynthetically active chloroplasts, and etiolated leaves transition from the “sink” stage to the “source” stage. De-etiolation has been extensively studied in maize (Zea mays L.). However, little is known about how this transition is regulated. In this study, we described a quantitative proteomic and phosphoproteomic atlas of the de-etiolation process in maize. We identified 16,420 proteins in proteome, among which 14,168 proteins were quantified. In addition, 8746 phosphorylation sites within 3110 proteins were identified. From the combined proteomic and phosphoproteomic data, we identified a total of 17,436 proteins. Only 7.0% (998/14,168) of proteins significantly changed in abundance during de-etiolation. In contrast, 26.6% of phosphorylated proteins exhibited significant changes in phosphorylation level; these included proteins involved in gene expression and homeostatic pathways and rate-limiting enzymes involved in photosynthetic light and carbon reactions. Based on phosphoproteomic analysis, 34.0% (1057/3110) of phosphorylated proteins identified in this study contained more than 2 phosphorylation sites, and 37 proteins contained more than 16 phosphorylation sites, indicating that multi-phosphorylation is ubiquitous during the de-etiolation process. Our results suggest that plants might preferentially regulate the level of posttranslational modifications (PTMs) rather than protein abundance for adapting to changing environments. The study of PTMs could thus better reveal the regulation of de-etiolation.

Corn straw is an abundant lignocellulose resource and by-product of agricultural production. With the continuous increase in agricultural development, the output of corn straw is also increasing significantly. However, the inappropriate disposal of straw results in wasting of resources, and also causes a serious ecological crisis. Screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. For this purpose, our research group isolated three actinomycete strains with efficient lignocellulose degradation ability from soil in the cold region of China: Streptomyces sp. G1^T, Streptomyces sp. G2^T and Streptomyces sp. G3^T. Their microbial properties and taxonomic status were assessed to improve our understanding of these strains. The three strains showed typical characteristics of the genus Streptomyces, and likely represent three different species. Genome functional annotation indicated that most of their genes were related to functions like carbohydrate transport and metabolism. In addition, a similar phenomenon also appeared in the COG and CAZyme analyses, with a large number of genes encoding carbohydrate-related hydrolases, such as cellulase, glycosidase and endoglucanase, which could effectively destroy the structure of lignocellulose in corn straw. This unambiguously demonstrated the potential of the three microorganisms to hydrolyze macromolecular polysaccharides at the molecular level. In addition, in the straw-returning test, the decomposing consortium composed of the three Streptomyces isolates (G123) effectively destroyed the recalcitrant bonds between the various components of straw, and significantly reduced the content of active components in corn straw. Furthermore, microbial diversity analysis indicated that the relative abundance of Proteobacteria, reportedly associated with soil antibiotic resistance and antibiotic degradation, was significantly improved with straw returning at both tested time points. The microbial diversity of each treatment was also dramatically changed by supplementing with G123. Taken together, G123 has important biological potential and should be further studied, which will provide new insights and strategies for appropriate treatment of corn straw.

Wide-narrow row maize planting patterns are a popular way to enhance maize yield via improving canopy PAR. To further optimize canopy PAR, we designed an improved wide-narrow row planting pattern (R2) based on the principle of the shortest pr...