Retardation of senescence by low temperature and benzyladenine in intact primary leaves of soybean

Effects of temperature and benzyladenine (BA) on the senescence of intact primary leaves of soybean were investigated. Compared with high temperature (30°C for day and 25°C for night), low temperature (15°C for day and 13°C for night) significantly retarded senescence of intact primary leaves. Repeated daily treatment of the primary leaves with BA (200 mg/liter) beginning 15 days after growth at high temperature resulted in retardation of the senescence process. The lower activity of cytokinins in the primary leaves of seedlings grown under high temperature may be responsible for rapid senescence.