Browsing by Author "PRAGNA, GUGULOTH"
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ThesisItem Open Access HYDRAULIC PERFORMANCE EVALUATION OF DRIP IRRIGATION SYSTEM FOR CABBAGE (Brassica oleracea L)(PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD, 2016) PRAGNA, GUGULOTH; G. MANOJ KUMAR, GA field experiment entitled „„Hydraulic performance evaluation of drip irrigation system for cabbage (Brassica oleracea L)‟‟ was carried out during Rabi season, 2015-16 at College Farm, College of Agriculture, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad, to evaluate the hydraulic performance of drip irrigation system for improving water productivity of cabbage. The treatments were laid out in split plot design with two irrigation levels namely 0.6 ETc (I1)and 0.8 ETc (I2) as main plot treatments and four discharge rates 1.6 lph (D1), 2.2 lph (D2), 3.0 lph (D3) and 4.0 lph (D4) were as sub-plot treatments. The experimental soil was sandy clay loam in texture, moderately alkaline in reaction and non-saline. The moisture content at field capacity was 18.25%. The system was tested for its uniformity co-efficient, emission uniformity, and the co-efficient of variation. The head discharge relationships at different operating pressure i.e. 0.5, 0.7, 0.9, 1.25 and 1.5 kg/cm2 for emitters were expressed and the best fitted model with highest R2 was determined. Twenty five day old cabbage seedlings were transplanted on 15th October 2015, maintaining a crop geometry of 40 x 40 cm with lateral spacing of 120 cm with paired row planting. Irrigation was scheduled based on crop evapotranspiration (ETc). Statistical analysis has been conducted to obtain the effect of different irrigation levels and dripper discharge on plant growth parameters like dry matter production (g/plant), root length (cm) and yield attributes like cabbage head weight (kg) and diameter (cm) and yield (t/ha). The input files of climate, crop, soil type, management (irrigation) and initial soil water condition were given into the Aqua Crop model. The model was run to simulate the yield and water productivity. Simulation performance was evaluated by calculating statistical co-efficient of determination (R2), prediction error (Pe), model efficiency (E), root mean square error (RMSE) and mean absolute error (MAE). Results indicated from developed models for the pressure discharge relationship that the exponent of the pressure was less than and equal to 0.5 which indicated that the nature of flow from the dripper was not an orifice flow. The co-efficient of variation values of all considered drippers at different operating pressure is estimated to be 0.04 to 0.1 infers that drippers are of good quality. The Emitter flow variation is also less than 25% which is in an acceptable range. Emission uniformity ranged from 81.78 % to 83.38 % at 0.5 kg/cm2 to 89.36 % to 89.94 % at 1.5 kg/cm2 for different drippers. Co-efficient of uniformity ranged from 92.15 % to 94.36 % at 0.5 kg/cm2 to 95.25 % and 96.21% at 1.5 kg/cm2 for different drippers. The uniformity co-efficient and emission uniformity increased while co-efficient of variation decreased as operating pressure increased for drippers. Among four levels of dripper discharge rates, 1.6 lph significantly gave higher dry matter production (g/plant), root length (cm), head weight (g) and diameter (cm) and yield(t/ha). Among two irrigation levels (0.8 ETc and 0.6 ETc), crop irrigated at 0.8 ETc gave higher yield but water use efficiency (t/ha-mm) is higher for crop irrigated at 0.6 ETc. Hence irrigation water could be saved by irrigating the cabbage crop at 0.6 ETc without compromising for the yield. Thus, in areas with water shortage condition, adopting irrigation at 0.6 ETc for cabbage production would give beneficiary results. The interaction effect of dripper discharge and irrigation levels was non-significant for all parameters. Prediction error for cabbage yield ranged from 8.23% to 11.96 % with an efficiency of 0.93. Prediction error for water productivity ranged from 1.15% to 3.5% with an efficiency of 0.73. The AquaCrop tends to follow closely the trend in the measured data of cabbage yield and water productivity, but with slight under and over estimations with acceptable range of prediction error