Crop co-efficient, Irrigation scheduling, Water rewuirement, Lysimeter, Cauliflower
Seedlings of cauliflower at 30 days old (variety: Snow white) were planted on 29 November 2009 in four lysimeter tanks maintaining row to row spacing and plant to plant spacing 60 cm and 45 cm , respectively. The crop was harvested at 27 January, 2010. The soil was silty clay loam with field capacity and bulk density, 28% and 1.5 gm/cc, respectively. The selected treatments were:
T1= Irrigations at 15, 25, 35, 45 days after planting (DAP) allowing drainage
T2= Irrigations at 15, 25, 35, 50 days after planting allowing drainage
T3= Irrigations at 15, 25, 40 days after planting allowing drainage
T4= Irrigations at 15, 30, 45 days after planting allowing drainage
The micro-lysimeter contains 4 tanks, each having an area of 1.0 m x 1.0 m. Therefore, no replication of the treatments was possible. Climatic data such as, maximum and minimum temperatures, air humidity, sunshine hours and wind speed together with the location information like elevation, latitude and longitude were incorporated in the software, ETo Calculator or CROPWAT to estimate the potential evapo-transpiration. The crop was irrigated in accordance with the design of the treatments. Measured quantity of water was applied to the tanks to ensure drainage. During the crop season, no rainfall occurred. Crop evapotranspiration (ETc) was measured by the following way:
ETct = (Wa + Re) – (Dw + Ss)
Where, ETct = crop evapo-transpiration in mm for time period, t
Wa = applied water, mm
Re = rainfall, mm, for time t
Dw = drainage water, mm, for time, t
Ss = stored soil moisture, mm, for time, t
Then from the potential evapotranspiration (ETo) estimated for the specified period, the value of Kc for the period was determined from the ratio, ETc / ETo.
Annual Research Report 2010, IWM Division, BARI, Gazipur
The crop coefficient values of cauliflower at initial, development, mid season and late season stages were found values of 0.48, 0.95, 0.91 and 0.75, respectively from the lysimeter study. The results obtained from the study are recommended for determining water requirement of cauliflower.