Identification of Tropical Late Yellow Maize Germplasm Under Waster Stress Conditions

Abstract

Drought is a limiting factor for maize production of Thailand. It damages an estimated annually 3 to 22% of the planted area, resulting in yield losses of approximately 129,000 to 858,000 metric tons. During the dry season of 2004, tropical late yellow maize (Zea mays L.) germplasm including 41 inbreds, 26 hybrids and 35 open pollinated varieties (OPV’s) were evaluated in separate trials under water stress during flowering stage and under non water stress conditions at Nakhon Sawan Field Crops Research Centre (NSFCRC), Tak Fa, Nakhon Sawan province. Each group, treatments were arranged in randomized complete block design with three replications. The water stress condition was managed by irrigation withdrawal achieving severe drought stress during flowering stage, compared to non water stress or well watered condition irrigated weekly. The objectives were to compare some agronomic traits of tropical late yellow inbred, hybrids and OPV’s and to identify superior germplasm for further use in hybrid development programme. Significant differences (P_0.05) were found among tested inbreds, hybrids and OPV’s for all traits measured. Grain yield (GY) of inbreds, hybrids and OPV’s were 772, 3,837 and 2,388 kg ha-1 with anthesis – silking interval (ASI) ranged from -0.3 to 10, 0 to 6.3 and 0 to 12 days, respectively. Grain yield was positively correlated with number of ears per plant (EPP), chlorophyll content (CHE) and number of seeds per row (SPR). It indicated that increase in GY under water stress was associated with increase in EPP, CHE and SPR. The ASI and LRO were negatively correlated with GY, suggesting an increase in GY was associated with a reduction in ASI and LRO. Several inbreds, hybrids and OPV’s showed good performance under water stress condition four inbreds, one hybrid and two OPV’s had greater grain yield (GY) and number of ears plant-1 (EPP), but shorter ASI than overall mean.