Selection strategy for grain quality traits in upland rice breeding programs

ABSTRACT The evaluation of grain quality traits is essential in rice breeding programs. However, their complexity and multitude of components make the process challenging. The aim was to evaluate the industrial, physical, chemical, and cooking quality traits of upland rice grains and to identify a reduced set of factors that accurately represent these traits, facilitating the indirect selection of desirable genotypes in the breeding programs. A total of 27 genotypes from the Value of Cultivation and Use (VCU) trial of the Upland Rice Breeding Program were evaluated in four environments over two years. The traits evaluated were total yield, milling yield, chalkiness, grain size, apparent amylose content, gelatinization temperature, minimum cooking time, water absorption index, volume expansion coefficient, hardness, and stickiness. The measured values were subjected to joint analysis of variance and principal component analysis (PCA). Subsequently, phenotypic correlation coefficients and path analyses of the traits that emerged prominently in the PCA were conducted. Grain size, water absorption index, and chalkiness are independent, indicating the importance of direct selection to achieve genetic gains. Apparent amylose content and gelatinization temperature are strongly associated, allowing for indirect selection between them.