The Study On The Methods Of Maize Inbred Lines Selected Under The High Density Conditions

This article studies how to select excellent inbred lines in high density on three aspects. Firstly, selected6inbred lines which from4main domestic heterosis groups and Pioneer groups, including Zheng58,MO17,Chang7-2,Dan340,PH6WC and PH4CV, was planted respectively in90,000/hm2,110,000/hm2,130,000/hm2,150,000/hm24densities. Studied the density-resistance and stress-resistance of the inbred line,as well as the best planting density. Secondly, using split plot design to plant hybrid cultivars(including JNY986, G748, JNY885, G684,Xianyu335and Zhengdan958) in6densities(60,000/hm2,75,000/hm2,90,000/hm2,110,000/hm2,150,000/hm2).Studied if the density impact on the yield components though the ANOVA, Path Analysis and yield comparison. Identified the optimal planting density. Thirdly,Taking PH4CVxchang7-2as the basic material, we selected inbred lines under the selective pressure of6×104plants/hm2,9×104plants/hm2,12×104plants/hm2and15×104plants/hm2. We composed the NCⅡdesign with4backbone inbred lines and5representative lines which were selected from the S3generation, and analyzed the yield performance; GCA and SCA.1. The analysis of density-resistance of the inbred line. This study chang7-2of ear length pointed in high and low density difference long minimum value, is0.4cm, and density of the correlation coefficient minimum of just0.1931, influenced by density slightly, these traits are the dominant. The ear height of Dan340is its dominant characters. Zheng58dominant traits is resistance to lodging ear. The MO17, it dominant is stem diameter. The PH6WC,whose dominant traits is more than others. So this inbred line is density-independent line. The representative of Pioneer high male group--PH4CV, whose dominant traits is ASI, ear row numbers, ear, ear diameter.The density experiment to6representative inbred lines indicated PH6WC,Dan340,Chang7-2and MO17The density of90000/hm2density (g) the highest yield per plant, were126.57,105.77,70.33,98.70. should be enlarge the inbred line selection density from the perspective of yield per plant. the upper limit, the effect is poor if surpass the limit. The inbred line selected density of PH4CV and Zheng58can be enlarged to110000/hm2density (g), the effect is poor if surpass this density.2. The analysis of density-resistance of the hybrid cultivars. The results of ANOVA to the traits indicated that the variation of the plant height and ear mainly depend on the hybrid per se, density influenced slightly. So these two characters can be not considered in density-resistance selection. Stems thick, long ears, ASI, yield per plant influenced by hybrid and density combined action. The miss rate, barren tip, ear diameter and row grains is influenced by the environment.The experimental condition, the combination G746in six density under the highest yield average,24.01kg. The empty bar rate lowest average,9.56%, bald, pointed the mean length minimum,1.00cm,-grain weight mean is the highest, about24.01g.MISS rate, bare-tip length,100-kernel weight is the important index traits to response the density-resistance. Different heterosis pattern hybrid combination has different density tolerance, the heterosis pattern of G746is Tong siping×Reid,this pattern is the best density tolerance pattern. Reid can be used to improve the Tang group, increase the stress resistance in the high density, increase the yield potential. The G684has the lowest yield,which from Lvdahonggu×Reid. This pattern is poor, has not reach the improved effect.Path analysis to the yield of hybrid in6density, rejected the indistinctive characters, the results showed that:in the density of60,000/hm2and75,000/hm2, the characters direct effect to the yield sored by size is seed rate in the density of90,000/hm2, the characters direct effect to the yield sored by size line grain number, in the density of110,000/hm2,130,000/hm2,150,000/hm2, the the characters direct effect to the yield sored by size hundred grain weight. This shows that different hybrid density various characters to yield contribution different size, low density in, consideration should be given to the increase of the hybrid seed rate, high density in main increase of hybrid in-grain weight.3.The best density of maize inbred lines selected The results indicated that: GCA of5inbred lines which selected under the12×104plants/hm2were all positive, the highest value12F-3was12.74, the parents who had the highest value of SCA were also came from the inbred lines under the selective density of12×104plants/hm2; meanwhile, the yield of the combination which derived from that density was much higher than the best of CK, the highest grain yield per plot was15.57kg from PH6WC×12F-5. We take the12×104plants/hm2as the best density for PH4CV×chang7-2combination among the4selective densities.