MSc

An investigation was carried out in Department of Agricultural Meteorology, College of Horticulture, Vellanikkara during 2015-16 to determine the the effect of growing environments and microclimate on growth and yield of cucumber and crop
weather relationships in cucumber under different growing environment. The study was
conducted in polyhouse, rain shelter and open field simultaneously at Agricultural Research Station, Mannuthy in a split plot design with 3 replications with six dates of
planting i.e., 15 January, 25 January, 5 February, 1 June, 10 June and 20 June 2015. The observations on morphological, phenological and yield attributes like plant height, leaf area index, biomass at the time of last harvest, days to first flowering and harvest, days to last harvest, percentage fruit setting, fruit yield per plant, average fruit weight, total yield, number of harvest and crop duration were recorded at different
stages of development of the crop. The weather parameters like temperature, relative humidity, solar radiation, soil temperature and soil moisture were recorded using automatic weather station installed inside each growing environment. The UV radiation
and carbon dioxide concentration were recorded using the UV biometer and CO2 meter respectively. Canopy temperature and Canopy Air Temperature Difference (CATD) was recorded using infrared thermometer. PAR was recorded using digital plant canopy imager. The date of transplanting and growing environment had a significant effect on the morphological, phenological and yield parameters of cucumber. The highest and lowest plant height was obtained for the crop planted inside the polyhouse and open field respectively. Maximum LAI was recorded in the crop transplanted inside the polyhouse on 1 June 2015 and on 10 January 2015 and the least values of maximum LAI was observed in the crop under the open field conditions transplanted on 20 January 2015.The highest biomass at the end of the crop was observed in the crop
transplanted inside the polyhouse on 25 January 2015. Polyhouse crops took least days to first flowering and first harvest. Total yield was highest in the crops transplanted
inside the polyhouse and average fruit weight, percentage fruit set and fruit yield per plant was also more in polyhouse as compared to rain shelter and open field. To determine the critical weather elements affecting the crop growth, correlation
analysis was done and it was observed that higher solar radiation, PAR and UV radiation showed significant negative correlation with crop growth, yield and yield attributing characters. Carbon dioxide concentration in the morning time (6 AM) is more inside the poly house as compared to open field and rain shelter. Multiple linear regression models were fitted, to predict the duration of crop, days to first flowering,days to last harvest, leaf area index and total yield based on weather variables. Even though, the light intensities were comparatively very less inside the polyhouse, this was the major substantiating reason for greater vegetative vigour of the
plants, both in terms of height and leaf area index. Lower light intensities delayed auxin destruction and promoted cell division and expansion. Higher LAI values, higher CO2 content which ensured relatively higher net photosynthesis rates and higher photosynthate formations and assimilation, higher percentage fruit set, optimum soil temperature resulted in high yield in cucumber. So within a polyhouse, it is possible to create a microclimate which is better suited for the development of crop than the outside environment, thus giving better
production and uniform quality.