Gramineous crops are the core crops for China's food security and stable agricultural production. However, the problem of lodging has long seriously restricted their high and stable yields as well as quality improvement. This article systematically reviews the main types, influencing factors, evaluation methods, genetic basis and improvement strategies of lodging in gramineous crops, and looks forward to the future research directions. Research shows that crop lodging is mainly divided into stem lodging and root lodging. Its occurrence is regulated in a coordinated manner by internal factors such as plant morphology and structure, stem mechanical properties and cell wall components, as well as external conditions such as natural environment and cultivation management. In terms of lodging assessment, methods such as field observation, model evaluation, and high-throughput remote sensing each have their own advantages and are suitable for different research and application scenarios. Important genes related to plant height, stem strength and plant type have been identified in several gramineous crops, providing a theoretical basis for genetic analysis and molecular improvement. Lodging-resistant breeding is shifting from traditional hybrid breeding and marker-assisted selection toward molecular design and gene-editing breeding, as well as genomic selection-assisted breeding.This paper further summarizes the current challenges of lodging resistance breeding and potential strategies for the improvement in gramineous crops: 1) Construct a field anti-lodging capacity prediction model based on small samples; 2) Analyze the common basis of lodging resistance traits in grasses and explore differentiated improvement strategies; 3) Construct precise molecular design breeding targeting key genes and cis-regulatory elements; 4) Establish a cultivation model that matches “variety-region-technology”, with the aim of providing theoretical basis and practical reference for the basic research and production practice of lodging resistance.
【Objective】Drought is one of the key factors causing wheat yield reduction, and developing wheat germplasm with strong drought resistance is a major challenge in current wheat breeding. Spring wheat plays a crucial role in safeguarding national food security. Clarifying the drought resistance of spring wheat germplasm will provide a basis for the exploration of drought resistant genes and drought germplasm innovation in spring wheat.【Method】In this study, a total of 396 spring wheat varieties (lines) treated with drought stress were used to determine the relative water content of leaves, chlorophyll content and leaf area index et al during the grain filling stage, and also measure plant height, spike length, and effective tillers et al in the maturity stage, the drought resistance coefficient of each index was calculated. A comprehensive evaluation of drought resistance for each spring wheat variety (line) was conducted based on descriptive statistics, principal component analysis, membership function method, cluster analysis and correlation analysis. 【Result】Compared with the normal irrigation conditions, all indices of each spring wheat variety in the grain filling stage and maturity stage decreased under drought stress. Among them, plot yield, leaf area index, and biomass showed higher decreases, while chlorophyll content, spike length, and relative water content of leaves exhibited the lower decreases. Significant differences were observed in drought resistance among the different varieties (lines). Under drought stress, the variation coefficient of each relevant index ranged from 6% to 34%, while the variation coefficient of each index ranged from 5% to 34% under normal irrigation condition. Principal component analysis was performed on the drought resistance coefficients of 4 indices at the grain filling stage and 8 indices at the maturity stage, 6 principal components were extracted with a cumulative variance contribution rate of 78.07%. The comprehensive drought resistance coefficient (D value) was calculated using the membership function value, and cluster analysis was conducted based on the D value to classify the 396 spring wheat varieties (lines) into 5 categories, followed by inter-group variance analysis, we found that the spring wheat varieties (lines) with strong drought resistance showed the highest plot yield, and it had the lowest decrease. Meanwhile, correlation analysis between the D value and the drought resistance coefficients of 12 indices revealed that the number of spikelets, biomass, flag leaf area, and effective tillers were considered as the effective comprehensive evaluation indices for spring wheat drought resistance identification. In addition, there were highly significant positive correlations between the relative water content of leaves and plant height, effective tillers, number of spikelets, biomass, the internode length below spike and plot yield, the chlorophyll content exhibited a highly significant correlations with 1000-grain weight, and flag leaf area had a remarkable positive correlations with spike length and 1000-grain weight under normal irrigation conditions. However, under drought stress, there were highly significant positive correlations between the relative water content of leaves and biomass, plot yield and 1000-grain weight, the flag leaf area had a remarkable positive correlations with spike length and biomass. Which indicated a close relationship between drought resistance indices in the grain filling stage and key agronomic indices in the maturity stage for spring wheat. 【Conclusion】There were 20 spring wheat germplasm resources with strong drought resistance that were selected in this study, which showed the highest yield and the lowest yield reduction under drought stress, and the number of spikes, biomass, flag leaf area, and effective tillers could be considered as the effective comprehensive evaluation indices for spring wheat drought resistance identification.
【Objective】In order to analyze the genetic diversity of tropical sorghum germplasm resources, screen for superior sorghum germplasms, and to provide a critical support for the innovation of sorghum germplasm and the breeding of the new cultivar that with high-quality and high-yield in the temperate regions of northern China.【Method】Taking 70 tropical sorghum germplasm resources as test materials, and 10 phenotypic traits of the test germplasm resources were observed in the field. Multiple statistical methods such as Shannon-Weaver diversity index, correlation analysis, cluster analysis and principal component analysis, stepwise regression analysis were comprehensively applied for the analysis and comprehensively evalution the genetic diversity of tropical sorghum germplasm resources in the temperate region of China. Molecular marker-assisted selection combined with conventional hybridization was used to carry out target trait design breeding, and a new high-quality and high-yield forage sorghum variety with both bmr and PS genes and safe seed production in the northern temperate regions was bred.【Result】The phenotypic variations of the germplasm resources were abundant, and the diversity indices of the 10 traits ranged from 1.44 to 2.00. Correlation analysis showed that the plant height was extremely significantly positively correlated with stem diameter, number of leaves, leaf length, leaf width and biological yield. The growth stage was extremely significantly positively correlated with Brix, but extremely significantly negatively correlated with plant height, stem diameter, number of leaves, leaf length and biological yield respectively. Cluster analysis divided 70 resources into 3 groups with significant differences in phenotypic characteristics. Principal component analysis reduced 10 trait indicators to 5 independent principal components, with a cumulative contribution rate of 85.921%. 10 elite resources including IS 18542 were selected based on the comprehensive evaluation scores (F value). The stepwise regression analysis showed that all of the 10 phenotypic traits could be used as key indicators for the comprehensive evaluation of forage sorghum. 3 photoperiod sensitive resources of Ma5/Ma6 genotype were identified, excellent parents lines 74A, 1390R and 107R and the new silage sorghum variety Long mu No.1 that with high-quality and high-yield was bred by molecular design breeding.【Conclusion】Based on the genetic diversity analysis and comprehensive evaluation of phenotypic traits, the extensive phenotypic variations and rich genetic diversity of tropical sorghum germplasm resources in temperate regions were clarified, and the 10 key indicators for the comprehensive evaluation of forage sorghum germplasm resources were determined. The genes pyramiding breeding had discovered and created excellent parents with both bmr gene and PS genes, and the new forage sorghum variety with high-quality and high-yield was bred, indicated that the forage quality and yield were improved at the same time.
【Objective】This study aimed to investigate the effects of different light quality combinations on the growth and development, photosynthetic physiological characteristics, expression of key flowering genes, and single-plant grain formation in barley (Hordeum vulgare L.), to optimize the light quality ratio, and to achieve a breeding configuration enabling multiple generations per year, so as to promote the application of rapid breeding technology in barley. 【Method】 Under controlled environmental conditions, two spring-type two-rowed beer barley cultivars, including Hua 22 and Yanmai 3, were cultivated under six LED spectral combinations: white light (W), red light (R, λmax≈660 nm), blue light (B, λmax≈450 nm), and red-blue composite lights (1R﹕1B, 1R﹕3B, and 3R﹕1B). The "accelerating effect" of different light quality combinations was comprehensively evaluated using the entropy-weighted TOPSIS method. This evaluation was based on monitoring key developmental stages throughout the entire growth cycle, measuring photosynthetic physiological parameters, analyzing the transcript levels of key flowering genes via quantitative real-time PCR (qRT-PCR), and assessing yield components (number of grains per spike and 1000-grain weight). 【Result】Under the white light (W) treatment, although Hua 22 and Yanmai 3 completed a generation cycle within 50 and 44 days, respectively, they exhibited a lower number of grains per plant and a reduced germination rate. In contrast, 3R﹕1B light combination ensured rapid barley growth (Hua 22, 56 days per generation; Yanmai 3, 49 days per generation), which also significantly improved the number of grains per spike and seed germination rates. No significant differences were observed in the SPAD value, photosynthetic parameters, or chlorophyll fluorescence parameters between the 3R﹕1B treatment and white light treatment. With the increase in blue light proportion, the whole growth period of barley was prolonged, and the SPAD value, photosynthetic parameters, and chlorophyll fluorescence parameters all decreased. qRT-PCR results indicated that light qualities with a high red light ratio accelerated the reproductive process by upregulating flowering-promoting factors, such as HvFT1, HvBM3, and HvAP1, as well as downregulating the flowering repressor HvRAV2-like.【Conclusion】The 3R﹕1B light spectrum not only ensured the rapid growth and development of barley but also significantly increased grain yield, achieving optimal multi-generation cycles per year. This study laid a technical foundation for rapid breeding in barley.
