Variation in Crop Co-Efficient of Maize Varieties under Irrigated Condition

Abstract

A field study was conducted on clay loam soil at the research farm of The University of Agriculture Peshawar during Kharif 2012 to determine the crop co-efficient of maize using two traditional (V₁=Azam and V₂=Jalal) and two hybrid (V₃=3025W and V₄=30K08) varieties having four replicates. Soil moisture was determined by gravimetric method, actual evapotranspiration (ETa) was worked out by field water balance taking into account soil moisture, rainfall, and irrigation water applied. The Potential evapotranspiration (ETo) was estimated by Pan Evaporation method. Crop coefficient (Kc) was determined by dividing ETa over ETo for all growth stages. ETa of traditional maize variety V₁ was found lowest and highest for hybrid maize variety V₄. Comparison of seasonal ETa of selected maize varieties showed that V₂, V₃ and V₄ had 3, 24 and 34 % higher values compared to V₁. ETa of V₁ varied between 2.7 to 4.8 mm d^-1, for V₂ between 2.6 to 5.2 mm d^-1, for V₃ between 3.3 to 6.2 mm d^-1 and for V₄ between 3.4 to 6.5 mm d^-1. The seasonal ETa of selected varieties V₁, V₂, V₃ and V₄ was found 411, 422, 512 and 550 mm, respectively. Results showed that ETa of hybrid varieties was higher as compared to traditional varieties. Kc values of variety V₁ ranged from 0.38 to 0.87, for V₂ it ranged from 0.38 to 0.91, for V₃ ranged from 0.43 to 1.13 and for V₄ ranged from 0.47 to 1.19. It was concluded that FAO reported Kc values of a crop are generalized one for a wide range of climate therefore,Kc value of each crop variety should be investigated and used.

Keywords:Crop coefficient, Actual crop co-efficient, Reference crop co-efficient and Crop water requirement.