Yield stability oil palm progenies in early and later years of production
The production of cultivars that are highly yielding and stable in performance over a wide range of environments is a major objective in the breeding of oil palm (Elaeis sp.). Progenies resulting from nine crosses of oil palm were evaluated in the early (1-10 years), late (11-20 years) and the combined (1-20 years) periods of production for number of bunches (NB), fresh fruit bunch yield (FFB) and mean bunch weight (MBW). There were significant progeny differences for all periods of production for the three traits. Generally, about 70% of the variation in each trait was due to factors which were common to all environments; i.e. E-linear. Progeny x E-linear was also significant in a few cases. Mean for each trait was also positively correlated with the regression coefficient (b-value). In these progenies, the patterns of genotype x environment interaction, as shown by the joint regression approach, appeared to be determined in the early years of production and remains more or less the same in later years. NB and FFB were less variable than MBW over all production environments; therefore, MBW may not be a good selection criterion for yield in the oil palm.