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.
