| Summary: | The research on physiological characteristics of soybean cultivar with resistant to
drought stress condition is still limited, so that information about it not widely
known. Therefore, required to extract the information to determine the physiological
characters associated with drought resistance. The objective of research was to
determine the physiological characteristics of soybean cultivars with resistant to
drought stress. The research was conducted at Tridharma Garden, Faculty of
Agriculture, Gadjah Mada University, Banguntapan, Bantul, Yogyakarta in
January - March 2012. The research was arranged in randomized complete block
design factorial with three blocks as replication. The first factors were cultivars of
soybean, namely: Willis (drought tolerant), Tidar (drought tolerant), Gema (drought
tolerant), Grobogan (drought sensitive) and Argomulyo (drought sensitive). The
second factors were watering interval, namely: 1, 2, 4 and 8 days. Drought stress
treatment started at 24 days after planting. The observations were done on moisture
content, leaf relative water content, leaf water potential, nitrate reductase activity,
chlorophyll a, chlorophyll b, total chlorophyll, relative chlorophyll content,
photosynthetic rate, number of stomata, proline content, width of stomatal opening,
transpiration rate, wilting level, sensitivity test, number of leaves, leaf area, shoot,
root and seed dry weight. The results showed that drought stress interferes with the
physiological characteristics of soybean cultivars, especially to the drought stress
sensitive cultivars such as Grobogan and Argomulyo. Meanwhile, the physiological
characteristics of drought stress tolerant soybean cultivars (Willis, Tidar and Gema)
were only slightly affected by drought stress. Wilis, Gema and Tidar cultivars able to
adapt to the drought stress conditions through the accumulation of proline compounds
and reducing the width of stomatal opening, transpiration rate and nitrate reductase
activity. Wilis, Gema and Tidar also have higher chlorophyll a, b and total, relative
chlorophyll content and photosynthetic rate when compared to Grobogan and
Argomulyo.
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