Genetic Diversity Of Maize Population A And B Of Shaanxi Province

Construction of breeding population in maize to expand the genetic base of maizegermplasm is an important way to increase genetic diversity. Study genetic diversity of theprogress in population improvement is important to maize germplasm innovation andutilization. In order to study genetic diversity and improved effect of maize population A andB of Shaanxi province, we analysed agronomic traits, SSR markers, and combining ability ofimproved materials of maize population A and B of Shaanxi province from different sites atdifferent years and materials selected from different water and nitrogen treatments. The mainresults were as follows:1. With the increase of improvement cycles, productivity per plant and seed rate ofPopulation A increased gradually. Productivity per plant increased by4.75g for each cyclywith an increase of10.85%after4cycles improvement; the seed rate increased0.0069for percycly with an increase of2.43%after4cycles improvement. Productivity per plant ofPopulation B increased by8.87g for each cycly with an increase of28.66%after4cyclesimprovement; the seed rate increased0.0040for each cycly with an increase of1.39%after4cycles improvement. Plant height and ear height of Population A decreased gradually with theincrease of cycles. Plant height and ear height of Population B decreased, too. For thepopulations, productivity per plant and seed rate gradually increased, plant height and earheight decreased gradually after4improvement cycles. Agronomic traits had been optimizedafter directional selection.2. Comparison materials of2populations selected from Ankang, Hanzhoung, Yangling,Baoji, Yanan and Yulin from2009to2011, we found that with the increase of cyclesproductivity per plant and seed rate of material from different sites gradually increased, andplant height and ear height gradually reduced. The difference of productivity per plant, seedrate, plant height and ear height among materials from different sites were great. Agronomictraits of material selected from different sites showed great difference.3. Compared productivity per plant of strain from irrigation with nitrogen, irrigation withno nitrogen, dry with nitrogen and dry with no nitrogen, we found that productivity per plantof strains from irragation with nitrogen was low, and strains with highest productivity perplant were derived from the adverse selection (irrigation without nitrogen application, dry with nitrogen, dry without nitrogen). Seed rate showed the same trends. So we can getexcellent material by selection under stress conditions.4. Using33SSR primers to evaluated the genetic diversity of different cycles groups,122alleles were detected in the2populations, the result showed that polymorphic locinumber in2populations increased gradually with the increase of cycles with an increase of8.33%and6.09%, respetively after4cycles improvement. Population improvement richedgenetic diversity of populations.5. Materials of the2populations selected from6sites were analyzed by SSR makers.Different materials were clustered into3groups. Ankang and Hanzhoung clustered into1group, Yangling and Baoji clustered into1group, and Yanan and Yulin clustered into1group.material selected under similarity environment had the similarity of genetic material.6. Analysis of combining ability of strains from different water, nitrogen fertilizertreatment showed that55%strains of Population A showed positive effect for GCA in yieldand Population B was40%, so Population A and Population B showed great combining ability.The mean value of GCA in yield per plant was highest for strains from drought withoutnitrogen treatment. While GCA of strains from irrigation with nitrogen was lowest. Thecombinations with highest SCA in yield of2populations were from strains selected underdrought without nitrogen condition. Yield of the combinations were10%higher than thecontrol (Zhengdan958). So we can get excellent strains from drought and low nitrogenconditions.7. SSR molecular markers proved that strains from same population had similar geneticbasis. Population A and population B belonged to two allele populations. By analysiscombining ability, we found that strains from Population A and population B had high generalcombining and special combining ability with91227and Chang7-2. There was strongerheterosis between Population A and population B.