Additive and Dominant Effect for Percent Brix of Stalk Juice and Estimated Stalk Sugar Content and Their Phenotypic Correlation in Corn (Zea mays L.)

Abstract

Recently it has been reported that percent Brix of stalk juice is applicable to indirect estimation of stover digestibility in forage corn. In this study, additive and dominant effect for percent Brix of stalk juice and estimated stalk sugar content (ESSC) were estimated by means of generation mean analysis for P_1, P_2, F_1, F_2, B_1 and B_2 generations of two crosses : Na26(flint)×Oh43 Ht (dent) and Na7 (dent)×Oh43Ht. Percent Brix was measured at the internode just above the top ear and ESSC was calculated as follows. ESSC=[(FW-DW)×percent Brix/{(100-percent Brix)×DW}]×100 where, FW=fresh weight, DW=dry weight. The relationship between percent Brix and ESSC was also investigated to clarify the effect of correction of percent Brix with dry matter content. Estimates of additive effect were approximately three times as large as dominant effect in both traits and both crosses. Estimates of dominant effect were small in both crosses and not significant in Na 26×Oh43Ht. Percent Brix was highly correlated with ESSC in segrigating generations, although the correlation were somewhat lower when percent Brix was higher than 9 to 10%. From the above results, it is inferred that selection of genotypes with high percent Brix of stalk juice is rather easy and percent Brix of F_1 hybrids is almost equivalent to the mid parental values. In indirect selection of stover digestibility, however, it is desirable that the preparatorily selected materials with high percent Brix are re-evaluated by ESSC.