Herry Suhardiyanto

Pendinginan Zona Perakaran (Root Zone Cooling) pada Produksi Benih Kentang menggunakan Sistem Aeroponik

High temperature is the major constraint to potato cultivation in the lowland for it causes stress and inhibit initiation of potato tuber. This study was designed to investigate the effects of root zone cooling upon seed potato production using aeroponics system in lowland wet tropical climates. Cultivation techniques used in this study was the aeroponics system with three cooling temperatures (10, 15, and 20 oC) and control (greenhouse room temperature). Plantlet of potato ‘Granola’ variety derived from tissue culture propagation were used. The results showed that the highest number of tuber and tuber weight that can be harvested up to 90 days after planting were obtained from cooling the root zone temperature at 10 °C with the average number of tuber 14.85 tubers plant-1and average weight of tubers 409.15 mg tuber-1. Plants grown at root zone cooling at 15 and 20 °C treatments produced lower number of tubers and lower tuber weight than at 10 oC, while plants grown at greenhouse temperature did not produce tubers. Keywords: cultivation techniques, Granola, high temperature, lowland tropical, potato tuber

Development of a ph Control System for nutrient solution in EBB and Flow Hydroponic Culture Based on Fuzzy Logic

Abstract This paper outlines the development of a fuzzy-based control system for maintaining a proper acidity (pH) level of nutrient solution in ebb and flow hydroponic cultures. The nutrient solution pH is kept at a desired set point by controlling two valves: (I) acid valve (to control me addition of acid solution necessary) and (2) base valve (to control the addition of base solution necessary). The control algorimm has been developed based on membership functions of fuzzy set. In order to get smoothness, the fuzzy rules have twenty-one linguistic statement which are determined by methods of trials and errors using the membership functions based on me skilled operators experience Applying me fuzzy logic to control me pH of the nutrient solution increased the smoothness of the pH tl1e during control course. Performance of the control system is discussed and recommendations are provided for future work.

Design and implementation of a computer-based control system for greenhouse in tropical regions

Abstract One difficulty of utilizing greenhouse technologies in a tropical area is to cope with: i) high level daily solar radiation, temperature, and humidity, ii) fluctuation and distribution of daily solar radiation, temperature, and humidity. This paper discusses our design and experimental results of a computer-based control system for greenhouse in tropical regions using PID and fuzzy logic control techniques.