Hubungan Aktivitas Nitrat Reduktase dan Kadar Klorofil Kultivar Kedelai Tahan Kekeringan
<em>Plants suffering from drought stress can be indicated by the changing of character on the morphology, anatomy and physiology, characterized by inhibition of leaf growth, accelerated root growth, stomata closure and leaf curly. Cultivars that are tolerance to drought can physiologically adapted by increasing prolin level reduce the osmotic potential in order to maintain turgor in the condition of low tissue water potential. The research was aimed to study the physiological characters of drought tolerant soybean cultivar of determine the relationship of nitrate reductase activity and chlorophyll content of drought-tolerance cultivars and susceptible to drought stress conditions. The research was conducted at Tridharma Garden Agricultural Faculty of Gadjah Mada University, Banguntapan, Bantul, Daerah Istimewa Yogyakarta from January to March 2012. The experiment was arranged on Factorial Complete Block Design with three replications. The first factor was soybean cultivar consist of five levels those are Wilis (drought tolerance), Tidar (drought tolerant), Gema (drought tolerant), Grobogan (susceptible) and Argomulyo (susceptible). The second factor was watering interval consist of four levels which were watering once a day, every 2 days, every 4 days and every 8 days. Drought stress treatment begans at 24 DAP. Parameters observed were moisture content, nitrate reductase activity, chlorophyll a, chlorophyll b, and total of chlorophyll at 56 DAP. Portable data analysis using SAS 9.1. for windows. The results showed that nitrate reductase activity contributes to greater levels of chlorophyll of drought tolerance cultivars "Wilis", "Tidar" and "Gema" on the conditions of drought stress than the susceptible cultivar "Grobogan" and "Argomulyo".</em>