Journal of Crop Production and Processing

Chlormequat chloride (CCC) as one of the most important growth retardants has been used for manipulation of growth and yield of cereal crops; however, the effect of CCC has not yet been well understood under drought stress conditions. Therefore, one greenhouse and a field experiment were conducted to examine the effects of CCC on yield and yield components of wheat in drought conditions at College of Agriculture, Shiraz University during 2012-2014 growing seasons. The treatments in greenhouse were application and no-application of CCC, wheat cultivar (Marvdasht, Shiraz and Chamran) and irrigation regimes (100%, 75% and 50% of FC); while the treatments in filed were different CCC concentrations (0, 3 and 5 g L^-1) and drought stress levels (no-, light-, moderate- and severe-drought). The results showed that under both greenhouse and field conditions, drought stress at different levels decreased yield and yield components of wheat cultivars. However, CCC improved drought tolerance in wheat with increasing yield and yield components; under field conditions, positive effects of CCC were enhanced with increasing its concentration up
to 5 g L^-1. The positive effect of CCC was greater under control and light stress compared to under severe stress conditions. In the greenhouse study where Marvdasht, Shiraz, and Chamran cultivars were evaluated, Chamran cultivar produced the highest grain yield under both normal and drought conditions; although Shiraz cultivar was found more responsive to CCC. Overall; drought stress reduced growth and grain yield of wheat crop; however, CCC could compensate, at least in part (i.e. 30% to 60%) for the latter reductions.