Comparative Preliminary Evaluation of Agronomic and Quality Traits of New"Zhongtang"Superior Lines

[Objectives]Sugarcane is the most significant sugar cash crop in the tropical and subtropical regions of China.However,it is notable for its narrow genetic basis,limited trait improvement,weak adaptability of varieties,and poor planting efficiency.In order to accelerate the process of sugarcane variety replacement and expand the basis of genetic variation,interspecific hybridization and multiple mutagenesis are the most effective methods for obtaining new sugarcane varieties.The evaluation and identification of phenotypic traits of germplasm represents a significant analytical method.The"Zhongtang"series of sugarcane varieties is distinguished by its high yield and high sugar content.New sugarcane germplasms with excellent agronomic and quality traits can be identified and developed as breeding parents and new breeding lines through comprehensive evaluation of the existing germplasm.[Methods]A total of 181 new lines were selected through genetic origin and orientation,and evaluated and appraised for growth,yield,and economic characteristics.The data on 6 important agronomic and quality traits,including tillering,initial plant height,plant height,stem diameter,number of effective stems,and brix at maturity,were used to discover superior lines.These traits were evaluated during the two production seasons of the participant lines.[Results]A comprehensive evaluation of seedling growth traits and economic traits at maturity of the experimental lines identified 30 excellent new germplasms of sugarcane.Among the selected lines,1501 and 1701 exhibited superior agronomic and quality traits,rendering them suitable as parental lines for sugarcane breeding or breeding as new varieties.[Conclusions]The exemplary results obtained in this study provide a solid foundation for the improvement of sugarcane germplasm,with the goal of enhancing quality and efficiency.These findings are of great scientific and practical significance to the study of sugarcane yield and sugar-related genes,as well as the exploration of the evaluation and utilization of sugarcane germplasm resources.

Effects of Space Radiation Mutation on Germination and Growth of Sugarcane Hybrid Seeds

[Objectives] This study was conducted to investigate the mutagenic effects of space radiation mutagenesis on sugarcane hybrid seeds. [Methods] Sugarcane hybrid spikes were subjected to space radiation mutagenesis treatment to identify the effects on the germination, seedling growth and plant growth and development of sugarcane hybrid seeds. [Results] The space radiation treatment had a great impact on the germination and growth of sugarcane hybrid seeds, especially on the germination of sugarcane seeds. The germination number per gram of seeds increased significantly, and the survival rate of seedlings increased significantly. The effect on the growth status was relatively small. The average number of tillers decreased slightly, the percentage of available stems increased, and the plants became higher, which resulted in a greater effect on sugarcane yield. Sugarcane sucrose was increased. The seed germination and late growth status indicated that space radiation promoted the germination and growth of sugarcane hybrid seeds. [Conclusions] This study provides a basis for the space radiation mutagenesis breeding of sugarcane hybrid seeds and the promotion of sugarcane breeding process.

Comprehensive Evaluation of Aluminum Tolerance in Sugarcane Varieties at the Seedling Stage and Screening of Identification Indexes

[Objectives]Aluminum toxicity is one of the important stress factors affecting sugarcane quality and yield in south China,breeding aluminum tolerant varieties is a cost-effective and practical way.In order to explore the characteristics of aluminum toxicity tolerance in different sugarcane varieties and establish the comprehensive evaluation system for screening and breeding new varieties with aluminum toxicity tolerance,this study was conducted to perform comprehensive evaluation of aluminum tolerance in different sugarcane varieties and screening of identification indexes.[Methods]With 26 sugarcane varieties bred in different ecological areas as materials,through a pot experiment,nine indexes which include sugarcane plant height,root length,shoot dry weight,root dry weight,root-shoot ratio,relative chlorophyll content,leaf proline content,and shoot and root aluminum contents at the seedling stage under acid-aluminum stress and control conditions were measured,and the aluminum toxicity tolerance coefficients of various indexes of each variety were calculated.On this basis,the aluminum tolerance of all varieties was comprehensively evaluated by principal component analysis,subordinate function,cluster analysis and stepwise regression analysis.[Results]Compared with the control,the nine indexes showed more abundant variation among the 26 varieties under acid-aluminum stress.The correlation analysis confirmed that the contributions of the nine measured indexes to aluminum tolerance were significantly overlapped,and the subsequent principal component analysis summarized and combined the ones with strong correlation among the nine indexes,converting them into two new independent comprehensive indexes.The cumulative contribution rate showed that the two new indexes covered 82.448%of the information of the original nine indexes.Then,the comprehensive evaluation D values of the acid-aluminum tolerance of the 26 varieties were calculated based on the subordinate function values combined with the weights of the contribution rates of the two new comprehensive indexes.By clustering analysis on the D values,the 26 varieties were divided into 3 groups.Three varieties with the highest D values among the 26 varieties,Yunzhe 11-1074,Zhongtang 2 and Haizhe 28,were classified as varieties with strong aluminum tolerance,and 11 varieties including Yuegan 56 and Guitang 58,were moderately aluminum tolerant,while 12 varieties including Haizhe 32 and Yunrui 10-187 were sensitive to aluminum stress.Finally,the optimal regression equation analysis was carried out with the comprehensive evaluation D value of aluminum tolerance as the dependent variable and the aluminum toxicity tolerance coefficients of various indexes as independent variables,and the evaluation model of aluminum tolerance in sugarcane was established.Root length,root dry weight,relative chlorophyll content,leaf proline content,shoot aluminum content and root aluminum content,which had significant effects on aluminum tolerance of sugarcane seedlings,were selected as the evaluation indexes of acid-aluminum tolerance of sugarcane seedlings.[Conclusions]This study not only obtained a number of aluminum-tolerant varieties,but also provides a theoretical basis and reference for future genetic breeding of aluminum-tolerant sugarcane.