PREDICTIVE MODEL FOR GRAIN CRACKING IN TERMS OF RICE PLANT AND PANICLE MORPHOLOGY DERIVED FROM MULTIVARIATE-ANALYSIS

Rice plant and panicle morphology in relation to grain cracking were studied in 17 varieties at four stages of maturity. The data were subjected to principal components analysis in order to identify structure within the data and reduce dimensionality. The first four factors collectively accounted for 72% of the trace. The first factor was dominated by yield and biomass related attributes, and the second with percentage cracked grains and grain moisture-III stage. The projection of varieties onto the planes defined by the first, second, third and fourth factors reflected scattering of varieties over all the quadrants indicating desirable wide variations in the varieties studied, and the results could be generalised. The discussions mainly centred on grain cracking which was primarily influenced by plant height, panicle length, grains/panicle, sequence of grain maturity and the microenvironments-particularly towards the last stages of maturity. Predictive models in terms of the above attributes explained more than 96% of cracking. The role of agronomic practices in controlling grain cracking is discussed. It is indicated that dwarf plants influenced by microenvironment need different panicle morphology and physiological sequence to minimise cracking as compared to tall plants which generally escape the influence of microenvironment.