Direct and Correlated Response to Recurrent Full‐sib Selection for Prolificacy in Maize¹

Abstract

Four cycles of full‐sib selection were conducted in ‘Partap’, an open‐pollinated cultivar of maize ( Zea mays L.), for prolificacy separately under low and high plant density environments. The four cycles were completed in 2 yrs by staggered sowing of evaluation experiments and breeding nurseries. Selected populations, one each from low‐ and high‐density experiments, were developed after each selection cycle resulting in eight populations. These, along with the original Partap were evaluated in three environments with two N levels and four plant population densities. Linear response per cycle for number of ears per plant was significant and was greater in the low‐density selection environment (0.06 ears = 5.5%) than in the high‐density environment (0.04 ears = 3.6%). There was a significant correlated increase of 4.5% per cycle for grain yield. Significant correlated responses were observed for several other traits also. In general, ear girth of both series of populations and number of kernel rows of the populations developed in the low‐density environment increased, whereas plant height and days to silk in both series of populations, and ear length and height in populations developed in the high‐density environment decreased as a result of selection. Selection for prolificacy, therefore, may be useful in developing high yielding, early maturing, and short statured genotypes.