对两个亚热带优质蛋白玉米群体的适应性混合选择研究——Ⅰ.开花期性状的直接选择响应

Effects of Mass Selection on Adaptive Improvement of Exotic Quality Protein Maize Populations Ⅰ. Direct Response to Selection for Early Silking

用混合选择法改良亚热带优质蛋白玉米(QPM)群体在我国北方长日照条件下的适应性。经过4轮选择,中群13和中群14两个群体在北京三年试验的平均抽丝日期分别从85.1和86.9天缩短为67.5和68.8天,平均每轮提早4.1和4.5天。散粉日期的变化幅度较小,平均每轮提早2.2和2.3天。由于这两个性状的选择响应有差异,使散粉至抽丝的间隔天数(PSSl)分别从11.2和12.2天缩短为2.4和2.5天,平均海轮缩短2.0和2.3天,大大改善了雌雄协调性。1991年在北京春播,三亚秋播和济南、武功、成都夏播所做的多点联合评价试验表现相同的趋势,两个群体的抽丝日期平均每轮提早2.0和1.6天,PSSI则平均每轮缩短1.11和0.97天。在北京长日照条件下积累的改良效果,在短日照和夏播条件下仍然表现极显著的选择响应。这表明,混合选择法是改良外来玉米种质适应性,提早开花和改善雌雄协调性的有效途径。

Two subtropical quality protein maize (Zea mays L.) (QPM) populations, C. Pop. 13 and C. Pop. 14, were under bi-parental mass selection for four cycles aiming at improvement of their adaptability to the long-day conditions in northern China.Analysis of variance indicated that significant progress (P<0.01) was available among populations for all traits under evaluation in the condition of Beijing. The mean days to silking and to pollen shedding at the cycle 4 of two populations were significantly (P<0.01)reduced than the original cycle, C0. In other words, they were earlier in flowering. The advanced cycles began to approach silking (67.5 and 68.8 days, respectively)nearly 17.6 and 18.1 days earlier than the origional cycles (85.1 and 86.9 days), giving an estimate of least square of b= -4.1 and -4.5 days per cycle, respectively. There seemed a less response to selection in days to pollen shedding over cycles, giving an estimate of least square of b = -2.2 and -2.3 days per cycle, respectively. Consequently, this would make pollen shedding to silking interval (PSSI = 2.4 and 2.5 days for C4) more niched than the original cycles (PSSI= 11.2 and 12.2 days for CO), as the gains in term of b were -2.0 and -2.3 days per cycle in C. Pop 13 and C. Pop 14, respectively.Similar evaluating experiment was conducted in Beijing (long-day condition), Sanya (short-day) and Jinan, Wugong and Chengdu (summer sowing with intermediate day length) in 1991. The results of 5-location experiments showed similar trends of response to selection (P<0.01) as in Beijing. The b values were -2.0 and -1.6 days per cycle for days to silking, -1.11 and -0.97 for PSSI, in C.Pop 13 and C.Pop 14, respectively. The selection progress gained under long-day condition in Beijing was also obtained under short-day or intermediate day length conditions. Therefore, mass selection is fairly effective in improving the exotic maize populations to adapt long-day conditions in temperate zone through earlier silking and better synchronized flowering of male and female flowers.