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Keywords:

  • dormancy-regulating chemicals;
  • desert grasses;
  • glycophytes;
  • salinity-induced dormancy;
  • seed germination

Abstract

The effects of dormancy-regulating chemicals (DRCs) on alleviating innate and salinity-induced dormancy (SID) were assessed in seeds of four perennial forage grasses (Pennisetum divisum, Sporobolus spicatus, Coelachyrum brevifolium and Centropodia forsskalii). These grasses have the potential to be used for restoration or rehabilitation of degraded rangelands of the Arabian Gulf deserts. The four species showed various levels of innate dormancy. Germination of seeds stored for 2 months was not enhanced by any of the five studied DRCs in both C. brevifolium and P. divisum, but significantly improved by thiourea, fusicoccin and gibberellic acid (GA) in C. forsskalii and by thiourea, fusicoccin and nitrate in S. spicatus. Salinity had a significant negative effect on all the studied grasses. Sporobolus spicatus was more tolerant to salinity, compared with the other species. The effect of DRCs on alleviating SID depended on species. Whereas DRCs had little effect on alleviating SID in C. forsskalii and P. divisum, they greatly alleviated it in S. spicatus and C. brevifolium. Partial alleviation was observed by fusicoccin in C. brevifolium and by GA, kinetin and thiourea in C. forsskalii. Nitrate, fusicoccin and GA resulted in a complete alleviation in S. spicatus seeds in 200 mm NaCl.