Phenotypic variation in physiological determinants of yield in spring sown safflower under Mediterranean conditions

Safflower (Carthamus tinctorius L) growth and productivity are influenced by many factors like genotype, environment and agronomic practices. This field study was conducted to investigate the effects of phenotypic variation in physiological traits on development and yield of spring sown safflower under Mediterranean conditions. Twenty-one genotypes of varying origin were grown for two growing seasons without irrigation. Data were recorded on phenological development stages and seed yield, seed oil content, harvest index (HI) and, seed growth rate (SGR), biomass growth rate (BGR) and economic growth rate (EGR) were determined. Seed yield varied greatly among genotypes and ranged from 1333 to 2870 kg ha(-1). There were large variations in SGR and EGR, which were linearly and positively related to seed yield and explained a large amount of the variation in yield, with r(2) values between 0.83 and 0.99. The relative contribution of biomass and HI to the variation in seed yield among genotypes appeared to be dependent on the growing season. When the environmental conditions allowed the genetically controlled variation in biomass production to become more apparent, most of the variation (87%) among genotypes in seed yield were due to the differences in biomass and were not resulted by genotypic differences in HI. Genotypes differed in seed oil content that ranged from 26.7% to 35.8%. Oil yield was mainly determined by seed yield in both seasons. Results indicated that spring sown safflower could be considered as an alternative rainfed crop in cool Mediterranean areas where winter kill is a problem. In conclusion, SGR, BGR and EGR were found to be important physiological determinants of seed yield, which could be used as additional selection criteria for yield improvement. (C) 2009 Elsevier B.V. All rights reserved.