Abstract. The study aimed to evaluate the effect of modified photoperiods and light intensities on grow-out production of tilapia under indoor tank culture system; specifically on water quality and on growth performance of tilapia. The study was conducted inside the greenhouse and considered two factors: photoperiod (24L:0D, 20L:4D and 16L:8D); and light intensity (40 watts m -2 , 60 watts m -2 and 80 watts m -2 ); also, a control treatment was set-up outside the greenhouse to receive the normal environmental condition. Light manipulations inside the greenhouse were able to sustain the water quality within the desirable level for tilapia cultured in tank; while control tanks shows high water quality variation. Growth performance of tilapia cultured in tank responds positively in prolonged photoperiod at different light intensities. However, light manipulation gave insignificant difference on feed conversion ratio and survival rate compared to normal condition. Results indicated that 20-hours photoperiod and 40 watts m -2 light intensity is just enough to sustain the recommended water quality and better growth performance of the cultured tilapia in indoor tank system. It can be concluded that longer photoperiod and restrained light intensity can improved the growth performance of tilapia under indoor tank culture.
Abstract. This study was conducted to develop an atmometer-based irrigation scheduling system for drip-irrigated onion production. The study was conducted at San Agustin, San Jose City Nueva Ecija from November 2016 -March 2017. Three treatments composing of three replicates were considered in the research. Treatments 1 and 2 were based on the recorded atmometer readings with an irrigation interval of two days and five days respectively. Treatment 3 is a soil moisture-based irrigation scheduling with a management allowed deficit of 50 %. Calibration curved was obtained by comparing the atmometer readings with the estimated evapotranspiration using Modified Penman-Monteith equation. It was used in computing the crop water requirement for Treatments 1 and 2. The important parameters that used to answer the objective of the study such as plant height, crop yield, bulb weight, bulb diameter, water use and water productivity, were acquired during and after crop production. The statistical analysis used in the study was Analysis of Variance for Complete Randomized Design and paired T-test. Based on the result, Treatment 1 was highly useful in increasing water productivity without sacrificing the crop qualities.
With the increasing cost of fossil fuel to generate power for cooling purposes, there is a need for alternative methods of cooling system that is sustainable and economically viable in producing high quality crops under tropical condition. This study aimed to investigate the effect of ground heat exchanger (GHE) for root-zone cooling on the growth, yield, and economic returns of aeroponically-grown strawberry plants under tropical greenhouse condition. The experiment had two treatments; the root-zone cooling methods (GHE, Air-conditioning Unit (ACU), and Control – no root-zone cooling) and photoperiods (8-hours, 16-hours, and 12-hours). We observed that the root-zone mean temperature under GHE was maintained at 26.75 °C, which was 2.61°C higher than ACU and 2.17°C lower than the control. The GHE and ACU did not significantly differ in terms of plant’s growth with larger and number of leaves, and longer petioles than the control. We found no significant interaction of the treatments on the yield nor difference between GHE and ACU with 181-186 g/plant. Projected benefit cost ratio using GHE is 4.24 and annual return of investment is at 32%. This study underscores the feasibility of GHE application for root-zone cooling under tropical greenhouse condition.
Aeration helps improve water quality and make it favorable to fish. SPFTAS was designed based on the environment and characteristics of freshwater ponds. SPFTAS consist of floating platform, power source, sensors, signaling and aeration system. It functions to disperse and increase dissolved oxygen (DO). It possessed capability to monitor real time condition of water, store data and send it through short messaging service (SMS). The SPFTAS oxygen transfer rate was 0.07 kg of oxygen using four diffusers and the standard aeration efficiency of 0.2710 kg oxygen/hp-hr. The standard oxygen transfer efficiency was 0.36 at 18 kg of oxygen transferred. SPFTAS increased DO level to 1.32 ppm and rated highly effective during the test. DO levels using 1, 2, 3 and 4 diffusers at different depths, distances and time results were significantly different. The DO level using different diffusers at time intervals was highest at 7.16 ppm in three hours operation. The total cost of automated SPFTAS was ₱ 170, 385.75. The cost analysis of using the machine indicated a breakeven point of 1, 440 hours per year. The annual operation expected save ₱ 32, 737.39 and expected recover the investment in 5.33 years. Finally, machine was found beneficial to increase DO concentration in fishponds.
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