Genetics of Vein and Stomatal Characters in Bromus inermis Leyss.1

Abstract

A half‐diallel involving seven parental clones of smooth bromegrass (Bromus inermis Leyss.) was used to elucidate the genetic variation of 14 characters, including width, vein number, vein frequency, interveinal distance, stomatal length, stomatal frequency, and the product of stomatal length and frequency for both leaf and sheath, Combining ability analyses showed that general combining ability (GCA) and specific combining ability (SCA) mean square values were significant, with the exception of the GCA mean square values for leaf vein frequency and interveinal distance. The preponderance of additive gene effects was evident from the variance components for vein number on both leaf and sheath, and leaf stomatal characters. High narrow‐sense heritabilities were estimated for these characters. Phenotypic and genotypic correlation coefficients indicated no association between leaf dimension and leaf vein frequency and interveinal distance. Plants with large leaf area, wide leaves, or high specific leaf weight tended to have high vein number, large stomatal size and low stomatal frequency. Selection for high vein frequency and narrow interveinal distance may increase forage yield of both the first harvest and the regrowth. Selection for small stomata on leaf and sheath, and high stomatal frequency on sheath, should improve forage yield of the first harvest.