Technical Abstract: In semi arid environments in-season rainfall events can be frequent and of varying amounts. Under such conditions the speed with which normal metabolism is reestablished in the plant can be an important factor in crop performance. Cessation of leaf expansion and growth is a response to plant water deficits in cotton. In an effort to determine the time-frame for resumption of leaf growth following rainfall, leaf expansion rates and cylcin activities were monitored in field-grown cotton. In a three year field experiment cotton (Gossypium hirsutum) was grown under full irrigation and rainfed conditions. Leaf water status was monitored by relative water content and pressure chamber methods. Rainfed plants experienced cycles of water deficit and recovery over the season. Expansion rates in uppermost expanding leaves (1cm sq) were monitored in situ on 24 hour intervals and the leaves were harvested for cyclin determinations. Total RNA was extracted from leaf samples. Northern gels were run and blotted. The blots were probed with an Arabidopsis D2 cyclin probe (J22). Cyclin presence was detected and was found to vary in response to plant water status.