KERNEL WATER CONTENT AND POTENTIAL SINK CAPACITY IN HIGHLAND MAIZE HYBRIDS

Abstract

In maize (Zea mays L.) potential sink capacity (PSC) at crop level can be estimated as the product of kernel number per unit area (KN) and maximum kernel water content (MKWC). PSC can be used to study the role of some growth factors on grain yield in response to changes in KN and individual kernel weight (KW). In this study we measured kernel water content and PSC in three commercial highland maize hybrids (‘Condor’, ‘H-48’ and ‘H-50’) in two sowing dates (normal: 11/04/08, and late: 29/04/08), two nitrogen rates (30 and 180 kg ha^-1) and two population densities (6.25 and 9.25 plants m^-2), during the Spring-Summer season of 2008 in Toluca Valley, México. All maize hybrids showed an increase in KN when N concentration and population density were increased in the two sowing dates. KN varied from 1500 to 2500 grains m^-2 thus reflecting the wide variation in growing conditions occurring during flowering and grain filling periods. The duration of the grain filling period was not affected by delaying the sowing date or decreasing the concentration of N; however, the highest N concen-tration induced a gain (P < 0.05) in grain filling rate, which reflected in higher values of MKWC and KW. Grain yield of these hybrids was strongly associated with PSC established during the flowering period and start of the grain filling period. These results highlight the importance of the deterministic role of a high PSC value to increase grain yield potential of Mexican highlands maize hybrids.