The easier and more economical control of root-zone temperature (RZT) as compared to that of other environmental factors such as air temperature could be an effective solution to temperature stress for the crop plants in hydroponics. The present study was designed to investigate the effect of root-zone temperature on the growth and yield of cucumber (Cucumis sativus L.) plants in recirculating hydroponic system under greenhouse of dimension, 9m x 30m during three cropping periods of the year in Oman viz. summer (June-August), fall (September-November) and spring (February-May) during year 2016/2017 at Directorate General Of Agriculture and Livestock Research of the Ministry of Agriculture & Fisheries located at Rumais Barka of Oman. The plants were grown in perlite medium at root-zone cooled temperatures of 22áµ’C, 25áµ’C, 28áµ’C treatments besides the control i.e. root-zone uncooled temperature of 33áµ’C as control treatment. The treatments were arranged in Complete Randomized Design (CRD) with four replications. The results indicated that the crop at root-zone temperatures of 22áµ’C and 25áµ’C gave the superior performance in terms of plant height, leaf number, chlorophyll content, leaf area cm2, fruit number/m2, yield in ton per greenhouse (t/gh), fresh and dry weight of shoot and root with significant differences between the treatments in all three periods. Fruit yield varied from 4.5t/gh to 6.4t/gh for root-zone temperature (RZT) and from 4.2 t/gh to 6.8 t/gh for the cropping periods. The higher yields of 6.4 t/gh and 6.4t/gh were found under RZT of 22áµ’C and 25áµ’C, respectively and were significantly higher (p<0.05) than that under control (33áµ’C; 4.5t/gh). In respect of cropping periods, the crop during fall period (February-May) gave higher fruit yield (6.8t/gh) than that during summer period (4.2t/gh). Â Thus the results indicated that cooling of root-zone temperature through nutrient solution is essential during high temperatures of summer (June-August) in Oman.Â
The agriculture investment decision affected by risk of capital and operation cost, yield and sale price of planted crops. This study examined risk of investment in green-house cucumber and tomato production and optimum mix of crop pattern at Al Batinah, Al Sharqiya Regions of Oman. The net present value with Monte Carlo simulation models are used to test risk efficiency and project viability. The result indicated that investment in two green-houses and growing one tomato crop and two cucumber crops (Tom1Cuc2) per year is more profitable and risk aversion. Stochastic Efficiency with Respect to a Function (SERF) performed and confirmed that (Tom1Cuc2) is the most risk efficient cropping system and got a positive NPV with 62% probability followed by growing tomato crop in two seasons with a positive NPV with probability of 58%. The study concluded tomato and cucumber producers are faced with different production and financial situations and their risk preferences play an important role in determining their production decisions. Risk premium analysis shows that greenhouse tomato growers need to be paid up to RO 2 847 to keep growing tomato instead of (Tom1Cuc2) cropping system. Greenhouse cucumber growers can sacrifices of RO 5 373 to justify not to switch from planting cucumber to grow (Tom1Cuc2) cropping system. Government subsidy should be given to farmers to construct new greenhouses to maximize their resource use efficiency, benefit from extended cropping season, protect their crops from adverse environmental conditions and increase food security.
One of the main concerns related to closed systems is the potential spread of root pathogens. With the recirculation of nutrient solutions, ozone treatment was tested for the efficacy against plant pathogen (Pythium), dissolved oxygen levels, growth and yield of cucumber crop in hydroponic closed system during December-March 2020/21. Two nutrient solution feeding tank were used one with ozone treated and other without ozone treated in randomized complete design (RCD) with four replication. The results showed that no plants were affected with pythium diseases in both treatments Ozone treated and untreated during winter season. Significant (p < 0.05) differences were observed in chlorophyll content, as SPAD values between the two treatments and their interactions in cucumber. Also, no significant differences were observed in yield between the two treatments.
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