Standardization of irrigation and fertigation requirement for amaranthus under polyhouse

Abstract

The study entitled “Standardization of irrigation and fertigation requirement for Amaranthus under polyhouse” was taken up to compute the crop water requirement, irrigation schedule and fertigation schedule of amaranthus (Amaranthus retroflexus) crop and to find out the best treatment which gives maximum yield under polyhouse conditions in Tavanur region. The CROPWAT 8.0 model developed by FAO was used for the determination of crop water requirement and irrigation scheduling. Climatological data including temperature, sunshine hours, wind speed and relative humidity were collected from KCAET, for the last four months (March to June 2019). The required soil, crop and climate data inputs were given to the model and the cropwater demand and irrigation schedule for amaranthus was obtained. Average ETo was found to be 3.62 mm/day. Water requirement for amaranthus was found as 194.2 mm and the gross irrigation requirement as 276.4 mm at a 100% irrigation eficiency. Field experiment was conducted inside the naturally ventilated polyhouse in the research plot of Precision Farming Development Center situated at KCAET, Tavanur, during the period March 2020 to May 2020. In the present study, 60%, 80%, 100% and 120% of ETc were selected as irrigation treatments and 75%, 100%, 125% and 150% of RDF were selected as fertigation treatment. In this experiment, the land was leveled and beds were raised. Amaranthus variety CO-1 was chosen for cultivation. The experiment was laid out in factorial completely randomized design. The plot was divided into 16 beds having 16 treatments with three replications and two factors. Fertigation include both macro and micro nutrients applied as water soluble fertilizers through fertigation system with venturimeter. Vegetative parameters and yield parameters for each treatment were observed during different stages of crop growth. Analyzing the effect of different treatments, it was found that in amaranthus crop, better performance was found in the treatment T3F2 (irrigation 100% of ETc and fertigation 100% of RDF).The highest plant height (69 cm), number of leaves (27 nos), stem girth (5.5 cm), width of leaf (11.5 cm), length of leaf (18.2 cm) and yield from plant (0.145 kg) was noticed in T3F2. The lowest yield was for T1F1 (irrigation 60% of ETcand fertigation 75% of RDF). The highest IWUE (Irrigation water use efficiency) was for T1F3 (93.3 kg/ha.mm) and lowest was for T4F1 (46.7 kg/ha.m). On economic analysis, Benefit Cost Ratio was found to be 1.334. The results of this experiment showed that it is possible to obtain better performance in terms of both growth and yied for amaranthus variety grown under polyhouse conditions under 100% of irrigation and 100% dose of nutrients as they might have served as optimum doses among the treatments. Hence drip fertigation with 100% of ETc and fertigation of 100% of RDF has been standardized for cultivation of amaranthus under poly house of PFDC, KCAET, Tavanur, Kerala. The results of the study can be used as a guide for the farmers to plan their irrigation and cropping pattern. Also the results can be extrapolated to the future to analyze the trends in future crop water demands.