MSc

An experiment was conducted at the Rice Research Station, Mannuthy, Thrissur during the period from November 1990 to April 1991 to study the influence of date os sowing and levels of irrigation on the growth and yield of watermelon (Citrullus lanatus) grown in rice fallows.
The experiment was laid out in split plot design with three replications. The treatment consisted of seven dates of sowing (November Ist, November 16th, December 16th, December 32st, January 15th and January 30th) in the main plot and four levels of irrigation (IW/CPE ratio of 1.0, IW/CPE ratio of 0.75, IW/CPE ratio of 0.50, pot watering -1 pot per day per pit) in the sub plot.
Observations on various morphological characters, flowering and yield attributes were recorded during the course of investigation. Soil moisture observations were taken before, and 24 hours after irrigation to compute consumptive use and soil moisture depletion. The daily values of various weather elements recorded at the meterological observatory were collected to work out the crop weather relationship.
The plants irrigated daily (10 litre/pit/day) were superior to others with regard to vine length, date of picking maturity, date and number of male and female flower production, number of fruits, fruit girth, weight, yield and total dry matter production, but was on par with IW/CPE ratio of 1.0. Irrigation at IW/CPE ratio of 1.0 was superior with regard to the number of nodes for female flower production and number of seeds per fruit. Irrigation treatment IW/CPE ratio of 0.50 recorded the highest sex ratio, hundred seed weight and T.S.S. content. The crop sown on November 16th was superior to others with regard to most of the crop characters.
The crop weather relationship studies showed that the temperature range during flowering and early fruit development (3rd to 7th week), maximum temperature during fruit development (7th to 10th week) and relative humidity during maturity (11th to 13th week) negatively correlated with yield. While for total dry matter production there was a negative correlation between temperature range during flowering (3rd to 5th week), maximum temperature during fruit development and early maturity (8th to 11th week) and relative humidity during maturity (11th to 13th week).
It was found that irrigation and sowing date has a significant effect on overall growth and yield of the crop. The highest yield was recorded in crop sown on November 16th irrigated daily (10 litre/pit /day). The best performance may be attributed to the optimum weather conditions during the crop period and the effective utilisation of water.
From the soil moisture studies it is evident that the consumptive use increased with the frequency of irrigation. The top 15 cm of the soil layer accounted for the highest soil moisture depletion. The depletion was more from the deeper layers in the drier regimes. The water use efficiency was highest for the plants irrigated at IW/CPE ratio of 0.5. sown on November 16th.
Results of the present experiment indica that at Mannuthy and surrounding water melon can be successfully raised in rice fallows if irrigated daily (10 litre/pit/day.) and sown in the middle of November.