热带亚热带玉米自交系耐密抗倒性鉴定评价OA

[Objective]The study aimed to screen tropical and subtropical maize inbred lines with strong density tolerance,so as to provide theoretical references for breeding density-tolerant maize varieties in the southwestern maize region of China.[Method]52 tropical and sub-tropical maize inbred lines were used as materials,and two planting densities,conventional density(55 000 plants/hm2)and high density(120 000 plants/hm2),were set to analyze effects of planting density on agronomic traits,yield traits,and lodging rate of maize inbred lines.Comprehensive evaluation of density tolerance of the inbred lines was conducted based on density tolerance coefficients,principal component analysis,membership function analysis and cluster analysis.[Result]Compared with conventional density planting conditions,under high density planting conditions,the unit yield,plant height,ear height,and barren ear tip of maize inbred lines all extremely significantly in-creased(P＜0.01,the same as below),while stem diameter,ear length,ear diameter,ear rows,and 100-kernel weight all extremely signifi-cantly decreased.Among the 52 maize inbred lines,45 exhibited a yield density tolerance coefficient greater than 1.000,accounting for 86.50％.Through principal component analysis,nine individual indicators were transformed into five comprehensive principal components,with a cumulative contribution rate of 77.87％.Among them,ear height,ear diameter,100-kernel weight,unit yield,and ear length had a significant influence on density tolerance of maize inbred lines.The membership function method was used to conduct comprehensive evaluation of densi-ty tolerance of maize inbred lines,and with cluster analysis,the 52 inbred lines were classified into three categories:type Ⅰ(strong density tolerance,16 lines,accounting for 30.77％),type Ⅱ(weak density tolerance,13 lines,accounting for 25.00％),and type Ⅲ(moderate density tolerance,23 lines,accounting for 44.23％).Under high-density planting conditions,29 inbred lines(55.77％)showed a lodging rate of 0.Among the 16 inbred lines of strong density tolerance,13(81.25％)had a lodging rate of 0.[Conclusion]The enhancement of maize unit yield lies in increasing planting density.Ear height,ear diameter,100-kernel weight,unit yield,and ear length can serve as main indicators for evaluating density tolerance of maize.The proportion of materials with strong density tolerance and lodging resistance in tropical and subtropical maize inbred lines is relatively high.In the breeding practice of density-tolerant maize,attention should be paid to applying maize inbred lines of strong density tolerance such as GML7322,Hybrid212,GML2020,LV61-2212,LV61-4321 and PR8-1311.