普通小麦穗轴节数发育遗传研究

Genetic Control of Rachis Node Number Development in Common Wheat (Triticum aestivum L.)

多穗轴节类（ ＭＲＮ） 小麦系指通过增加小穗着生部位（ 穗轴节） 来提高每穗小穗数的遗传类型。通过ＭＲＮ、普通穗类（ＣＳ）、（ ＭＲＮ×ＣＳ）Ｆ１ 及ＭＲＮ 衍生品系穗轴节发育特征比较，探讨穗轴节发育遗传及其与生育期长的不利特征的关系。结果表明：ＭＲＮ 的初始穗轴节数目多、分化期长，部分基因型初始穗轴节分化速率也高于ＣＳ；多穗轴节类的穗轴节数多可能源于初始穗轴节数和后生穗轴节数增加，其中初始穗轴节数增加是主要的因素；抽穗晚的主要原因是初始穗轴节分化期长；由于初始穗轴节数和初始穗轴节分化期受不同的遗传控制，因此在育种工作中要克服多穗轴节类生育期长的不利性状是可能的。

Genotypes, with significant more rachis nodes, thus more spikelet number per spike than CS (Common Spike) in wheat, are named MRN (Multiple Rachis Node) wheat. Formation of spikelets could be divided into two different, relative phases: development of rachis nodes (RN) and development of spikelets. Studies on developmental differences of RN formation between MRN, CS and (MRN×CS)F 1 were conducted under field condition. The MRN lines were characterized by a higher number of IRN (Initial Rachis Node) per spike, prolonged IRN developmental phase, and late heading date, while CS lines had relatively lower IRN number, shorter IRN phase, and earlier heading date. Higher IRN number was found to be dominant in (MRN×CS)F 1 and IRN phase, heading date under the same genetic control with dominant/super dominant for short duration. Higher rate of IRN producing in some MRN lines might be governed by dominant gene. Characters in ARN (Additional Rachis Nodes) developmental phase of MRN behaved differently with genotype, seemed to be governed by more complex genetic control. It is suggested that the formation of MRN be mainly determined by higher IRN, while late heading date is due to the prolonged IRN phase. Genetic differences between IRN number and IRN phase, revealed in this paper, give a practicable possibility to produce early MRN lines.