Document Type: Research Paper
Gorgan University of Agricultural Science and Natural Resources, Dept. of Agronomy, Iran.
Cotton Research Institue, Gorgan, Iran.
Restricted water resources are a limiting factor for irrigation applications throughout the world. The effects of irrigation regimes (amount) on cotton lint yield are known, but there is little information on the effect of irrigation regimes on seed quality of cotton. In this study, the effects of deficit irrigation after the onset of flowering on lint yield and seed quality of cotton (Gossypium hirsutum L.) with a drip irrigation system were evaluated during 2006 and 2007 in the northern Iran. After the onset of flowering, four irrigation regimes (0, 40, 70 and 100% of Class A pan evaporation (%PE)) were applied when the cumulative evaporation amount from class A pan reached approximately 40-50 mm. Lint yield showed a quadratic response to %PE and maximum lint yields were achieved with 82 and 91% PE irrigation regimes in 2006 and 2007, respectively and seed quality (based on standard germination and seed vigor tests) increased with a decrease in deficit irrigation. Thus when the amount of applied water was reduced by 30 (70% PE) and 60% (40% PE), decrease in lint yield was about 4 and 14%, respectively. The results of this study showed that irrigation treatments of 40-70% PE would be optimum for lint yield and seed quality production under drip irrigation.