EFFECTS OF TEMPERATURE, SOIL-WATER STATUS AND DEPTH OF PLANTING ON GERMINATION AND EMERGENCE OF MAIZE (ZEA-MAYS) ADAPTED TO SEMIARID EASTERN KENYA

The effects of temperature and soil water potential on maize germinati on were investigated in controlled environment conditions and the effe cts of depth of planting and a mulch on maize emergence were studied i n a field experiment in eastern Kenya. The rate of germination increas ed to an optimum temperature of 33.6-degrees-C above a base temperatur e of 6.1-degrees-C and decreased above the optimum to zero germination at 42.9-degrees-C. The thermal time for median germination increased from 51.5-degrees-Cd to 56.4-degrees-Cd as soil matric potential decre ased from -5 to -40 kPa. Soil water content, depth of planting, and th eir interaction had significant (P < 0.001) effects on final germinati on and emergence but mulch, or any interactions involving mulch, had n o such effects. Increasing depth of planting by 1 cm increased the the rmal time required for emergence by 2.8-degrees-Cd, and decreasing wat er content by 1% increased the thermal time required for emergence by 3.2-degrees-Cd.