Responses of Corn to Drought and to Nittrogen and Phosphorus Fertilization during Recovery from Drought Stress

Abstract

The response of an open-polinated Nakhon Sawan 1 (NS 1) and two hybrid (Pioneer 3012 and CP-DK 888) corn vrieties to drought and to nitrogen (N) and phosphorus (P) fertilizers applied soon after termination of drought was studied in the field during the dry season (january - April) of 1996 and 1997 at Nakhon Sawan Field Crops Research Center. Water regaime consisted of the control and drought treatments. The control plots were received sprinkler irrigation water with sufficient amount (40 mm) just after planting, 7 days after emergence (DAE) and then every 7 days until 98 DAE. While the water stressed (drought) plots also received 40 mm of water at planting were supplied only 10 mm of water at 7 DAE and were witheld from irrigation water scheduled at 14, 21 and 28 DAE. Then, the resumption of sufficient water supply was from 35 DAE. In 1996, NS 1 and Pioneer 3012 were used but CP-DK 888 was used in place of Pioneer 3012 in 1997. Either none, N, P (as P2O5) or N+P fertilizers of 93.75 and 62.50 kg N or P each/ha was applied at 37 DAE in 1996 and 1997, respectively. However, 31.25 kg N and P/ha was added to all plots at planting in 1997. At the end of a drought period (35 DAE), top dry mass, leaf areas and N and P concentrations in the tops of all 3 corn varieties were adversely affected by drought but being relatively more severe in NS 1. Overall, either hybrid gave higher grain yield than NS1, regardless of. water regime and N and P fertilization. An application of either N, P or N+P fertilizers few days after the start of a recovery period (37 DAE) could restore the final grain yields of perviously water-stressed corn plants.