Influence of silk age on grain yield and yield components of normal and male-sterile maize (Zea mays, L.)

Maize yield can be increased by a mixture of a cytoplasmic male-sterile hybrid and a low percentage of an isogenic or non-isogenic pollinator hybrid (10 to 20%). Then the flowering of ears and tassels should be well synchronized, a shortage of pollen or an aged silk might decrease the success of pollination and therefore, reduce grain yield. One experiment (in 1998) with one hybrid in Switzerland and two experiments (in 2000 and 2001) with two hybrids in Thailand were conducted to estimate the influence of different pollination dates on the pollination success for male-fertile and male-sterile maize. A cytoplasmic finale-sterile hybrid was used in Switzerland, and plants in Thailand were detasseled. All the plants were manually pollinated with fresh pollen. The optimal pollination date did not depend on the male fertility of a plant. The maximum number of grain sets at ample pollen supply and one pollination date was usually attained 3 to 5 days after the emergence of the silk and started to decrease at 7 days silk. Under a limited supply of pollen the grain set declined faster. Although grain yields and yield components differed between experiments, male sterility had neither a negative nor a positive impact on the grain set at delayed pollination date.