关键词: 多穗轴节类, 穗轴节数, 发育遗传, 抽穗期, 普通小麦

Abstract: 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)F₁ 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)F₁ 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.

Key words: MULTIPLE RACHIS NODE (MRN), RACHIS NODE NUMBER, DEVELOPMENT GENETIC, HEADING DATE, TRITICUM AESTIVUM L.