THE GENETICS OF STOMATAL LENGTH AND FREQUENCY IN CLONES OF BROMUS INERMIS AND THE RELATIONSHIPS BETWEEN THESE TRAITS AND YIELD

Abstract

Stomatal length and frequency were studied using a 7 × 7 diallel cross of smooth bromegrass (Bromus inermis Leyss.) clones and compared with data from an earlier study of the agronomic traits of the crosses. Silicon rubber impressions taken on different parts of a leaf, as well as on different leaves, showed that though variation was small for stomatal size, it was present for stomatal frequency. General combining ability was highly significant for both stomatal characters. Differences among the seven clones were marked. Both stepwise multiple regression and factor analysis were used to investigate the dependence structure that existed for stomatal and agronomic characters. Partial regression coefficients showed that stomatal frequency was related to yield. Factor analysis showed that the two stomatal characters accounted for 20% of the total variation in the dependence structure, whereas characters such as date of head emergence and plant height only accounted for 15%. These results reflect the importance of stomatal size and frequency in a breeding program in relation to agronomic practices.