INFLUENCE OF ENDOSPERM CELL NUMBER ON KERNEL SIZE AND WEIGHT IN MAIZE (ZEA MAYS L.)

CESAR AUGUSTO BRASIL PEREIRA PINTO, Purdue University

Abstract

Kernel size and weight in maize respond to physiological and environmental treatments especially in the early stages of kernel development. This sensitive early stage is the period when cell division occurs, suggesting that number of cells per endosperm might be related to kernel size and weight. The objectives of this study were: (i) to determine the relationship of endosperm cell number and kernel size and weight, and rate and duration of grain fill; (ii) to determine the contribution of number and size of starch granules to kernel weight and their relationships to endosperm cell number, and rate and duration of grain fill; (iii) to evaluate the effects of rates of applied N on endosperm cell number and the associated responses on kernel size and weight. A planting date experiment (planted on 12 May and 31 May) was conducted in 1983 and a N-rate experiment, including three levels of applied N (0, 90, and 270 kg ha('-1)) was carried out in 1984. Three single cross hybrids (P3732, B73 x Mo17, and B73 x Mo17 opaque-2) were randomly assigned to whole units in a randomized complete block design with three replications. In 1984, I used the same single cross hybrids but in addition, paired-row plots involving P3732 and B73 x Mo17 were planted and reciprocal crosses were made. Samples were taken every two days starting at 8 days after pollination (DAP) up to 24 DAP. Thereafter, samplings were made every 8 days until maturity. Endosperm cell number was positively associated with endosperm (r = 0.849**) and kernel (r = 0.831**) dry weights, rate of grain filling (r = 0.734**), kernel volume (r = 0.690**), starch content (r = 0.872**), and number of starch granules per endosperm (r = 0.763**). Nitrogen fertilization increased all parameters studied. An endosperm dosage effect was observed for endosperm cell number in response to N fertilization. Endosperms from P3732, P3732 x (B73 x Mo17), (B73 x Mo17) x P3732, and B73 X Mo17 were increased in cell number by 24, 40, 44, and 72%, respectively, from the zero level of applied N treatment to 270 kg N ha('-1). Starch granule number was more important than granule size in determining differences in kernel dry weight. Number of starch granules per endosperm increased as a consequence of the larger number of endosperm cells. Final kernel size was dependent in part on the amount of water taken up by the kernels during the early to mid stage of development.

Degree

Ph.D.

Subject Area

Agronomy

COinS