MS1与MS1-HS两种选择方法在玉米群体ZZ4中的改良效果比较Ⅰ.主要农艺性状的变化

对中综4号（ZZ4）完成了4轮改良S1-半同胞联合家系选择（简称MS1-HS）和4轮改良S1后代选择（简称MS1）。结果表明：以籽粒产量为主要目标的MS1-HS选择，每轮群体自身产量获得3.6%的遗传增益，群体S1后代籽粒产量可获得6.6%的增益；MS1选择每轮群体则可获得4.0%的遗传增益，群体S1后代籽粒产量可获得7.3%的增益。单穗籽粒产量

Improvement Effect of MS1 and MS1-HS Recurrent Selection on Maize Population ZZ4 I.Changes of Major Agronomic Traits

Four cycle of modified S1 HS recurrent selection (MS1 HS) and modified S1 progeny (MS1) recurrent selection aiming at improvement of grain yield in ZZ4 maize ( Zea mays L.) population have been completed in northern China. The responses to major agronomic traits for two methods in ZZ4 were evaluated in 2000 at four locations. Analysis of variance indicated that significantly progress( P <0.05)was available among populations for all traits .The grain yields of the cycle 4 populations in ZZ4 with two methods were significantly( P <0.01)higher than that of the original population(C0). The gains of grain yields per cycle were 3.6% and 4.0% for MS1 HS and MS1 selection methods respectively, giving an estimate of least square of b =163.4 kg/ha and 181.1 kg/ha per cycle, respectively. There seems a stronger response to selection in the average grain yield of S1 progeny of population per cycle, the gains were increased by 6.6%(MS1 HS) and 7.3%(MS1) as the gains in term of b were 249.7 kg/ha and 256.4 kg/ha for MS1 HS and MS1 selection methods respectively. The increase of grain yield per plant relied mainly upon the increases of ear length and number of kernels per row, secondly upon ear diameter and number of rows per ear. But the shelling ratio and 1 000 kernel weight were less increased. The correlated response of the other major agronomic traits was gained with selection by two methods. The plant height and ear height were increased cycle by cycle, but the resistances of lodging and wilting ect. were increased with selection by both two methods. The mean days to silk emergence and pollen shedding for the population with 4 cycle selections were about two days late than that of the original population(C0).