Comparative Evaluation of Naturally Ventilated Polyhouse and Rainshelter on the Performance of Cowpea

Abstract

A study was conducted in the Instructional Farm of KCAET, Tavanur, Kerala, during the period from August to December 2014 to compare the performance of cowpea grown under polyhouse and rainshelter in relation to open field cultivation. Cowpea variety Vellayani Jyothika, a trailing type legume released by KAU, was used for the study. Fertilizers were applied through drip irrigation system using venturi assembly. The variation of weather parameters such as maximum and minimum temperature, relative humidity, soil temperature and rainfall during the crop growth period was studied. Mean monthly values of temperature, relative humidity and soil temperature inside the polyhouse was higher than that in rainshelter and open field throughout the growth period. The maximum rainfall (360.7 mm) was recorded in the month of October and minimum rainfall (6.3 mm) was recorded in the month of December. Crop growth parameters such as plant height, internodal length, number of branches and time taken for flower initiation were noted during various crop growth stages for all the treatments. During all growth stages, the plant height and internodal length were significantly higher inside the polyhouse followed by rainshelter and open field. Among the different treatments, early flower initiation (39 days) was noted in the polyhouse. Yield parameters such as number of pods per plant, average length of pods and total yield per plant for each treatment were noted during various crop growth stages. The number of pods per plant was significantly higher in open field. Average length of pods inside polyhouse and inside rainshelter was higher than that in the open field. There was no significant difference in total yield of cowpea harvested from the observation plants under the three treatments. The maximum Benefit Cost ratio of 1.73 was obtained in the open field cultivation. Benefit Cost ratio of polyhouse and rainshelter were 1.06 and 1.34 respectively. Incidence of pests and diseases were also comparatively low inside the rainshelter and higher incidence of pests and diseases were noticed in the open field. From the results of the study it was evident that growing cowpea (Vellayani Jyothika) inside the rainshelter is more profitable than growing it inside naturally ventilated polyhouse.