Irrigation scheduling studies on soilless culture media for Polyhouse cultivation of vegetable crops

Abstract

Field study on the effect of alternate growing systems and irrigation schedules for soilless culture of salad cucumber and okra under drip irrigation was conducted inside the naturally ventilated polyhouse in the research plot of Department of Irrigation and Drainage Engineering situated near the LH KCAET, Tavanur, during October 2018 to January 2019. In the present study coirpith, perlite and vermiculite (3:1:1) and Ernakulam KVK media are selected as substrate media and data on climatic parameters, plant morphological parameters, chemical properties and yield parameters were recorded. In this experiment, the land was levelled and beds were raised. Okra variety Varsha Upahar and salad cucumber variety Hilton were chosen for cultivation. The experiment was laid out in factorial completely randomized design. The plot was divided into 2 parts with okra on one half and salad cucumber on other half having three treatments with three replications and two factors. Fertigation in coirpith, perlite and vermiculite and Ernakulam KVK media include both macro and micro nutrients applied as water soluble fertilizers from two tanks (tank A and tank B) through fertigation system with venturimeter. Data about vegetative parameters for each treatment were observed during different stages of crop growth. The results on the effect of alternate growing systems used, irrigation frequency and their combined effect on crop growth and yield parameters were statistically analyzed. Analyzing the effect of alternate growing systems, it was found that in okra crop maximum vegetative growth was found in coirpith, perlite and vermiculite mixture whereas higher yield was obtained in KVK media. The highest yield was for Ernakulam KVK media in once in three day irrigation (102.66 g/plant) followed by coirpith, perlite and vermiculite media in alternate day irrigation (88g/plant). In salad cucumber with once in three days irrigation in coirpith, vermiculite and perlite media provided us with a considerable yield and in terms of vegetative growth daily and alternate irrigation scheduling in the same media were found to be better. The highest yield was for once in three days irrigation in coirpith, vermiculite and perlite media (251.33g/plant) followed by Ernakulam KVK media in once in three day irrigation (176.66 g/plant). Irrigation interval significantly affected irrigation water use efficiency (IWUE). In okra the highest IWUE was for Ernakulam KVK media in once in three day irrigation (41.63kg/ha.mm) and lowest was for coirpith, perlite and vermiculite media in daily irrigation (2.88kg/ha.mm) whereas in salad cucumber highest IWUE was for coirpith, perlite and vermiculite media in once in three days irrigation (75.3 kg/ ha.mm). Even though crops under alternate day irrigation were identified with remarkable yield, once in three days irrigation can be suggested in the areas experiencing water shortage. The results of this experiment showed that it is possible to obtain satisfactory yields of okra and salad cucumber variety grown under polyhouse conditions in two different media under varying irrigation schedules. The KVK media is nutrient rich soilless media so fertigation required was less whereas inert growing media like coirpith demands full fertigation with all macro and micro nutrients.