Genetic control of paste viscosity characteristics in indica rice (Oryza sativa L.)

Paste viscosity parameters play an important role in estimating the eating, cooking and processing quality of rice. Four cytoplasmic male-sterile (CMS ) lines and eight restorer (R) lines were employed in an incomplete diallel cross to analyze seed effects, cytoplasmic effects and maternal gene effec ts on the viscosity profiles of indica rice. The results indicated that the viscosity profiles of rice were controlled by the direct effects of the se ed, by the cytoplasm and by maternal plant. The seed-direct effects (V-A V-D) accounted for over 51% of the total genetic variances (V-A + V-D + V-C + V-Am + V-Dm) for all the traits, suggesting that seed direct effects wer e more important than maternal effects and cytoplasmic effects. The additiv e variances (V-A + V-Am) were much larger than the dominance variances (V-D + V-Dm,), which revealed that additive genetic effects were the major cont ributors of genetic variation for the paste viscosity profiles, and that se lection could be applied for viscosity traits in the early generations. Sig nificant cytoplasmic variance (V-C) was detected for hot paste viscosity (H PV), cool paste viscosity (CPV) and consistency viscosity (CSV). The cytopl asmic effects for these three traits can, therefore, not be neglected in ri ce breeding. It was also shown that seed heritabilities (h(0)(2)) tended to be larger than maternal heritabilities (h(o)(2)) and cytoplasmic heritabil ities (h(c)(2)). Prediction of the main genetic effects for 12 parents show ed that CMS lines had highly positive effects on all the traits except for the breakdown viscosity (BDV), and that R lines had both positive and negat ive effects on the paste viscosity characteristics.