Impact of deficit irrigation on the physiological and agronomic traits of 24 safflower (Carthamus tinctorius L.) genotypes grown in Iran

The impact of two irrigation regimes (well-watered versus water limited conditions) on yield and grain composition of 24 safflower genotypes was compared in a two-year field trial arranged as a split plot design. Safflower genotypes at limited irrigation had higher total chlorophyll and proline levels compared with well-watered irrigations. In term of total chlorophyll content, safflower genotypes G17 (1.4 mg g-1 FW), G24 (1.37 mg g-1 FW) and G7 (1.36 mg g-1 FW) were statistically higher relative to other genotypes under well water conditions. In contrast, under limited irrigation conditions, G15 (1.76 mg g-1 FW) had the highest total chlorophyll suggestive of differential response among genotypes. The highest plant height and leaf dry weight were detected in G3 (84.4 cm and 13.3 g plant-1, respectively) under limited irrigation. Difference in number of heads plant-1 under well-watered (29.5 plant-1) was observed compared to limited irrigation (20.5 plant-1) among genotypes. Under well-watered (49.8 g) and limited irrigation (44.1), G2 and G9 showed the highest 1000 seed weight, respectively. Among accessions, G24 yielded more seed compared to other genotypes under well-watered (2342 kg ha-1) and limited irrigation (1137 kg ha-1) posing it as potential line for further breeding. With regards to seed oil yield, G23 was the highest under well-watered (735 kg ha-1) and water limited conditions (356 kg ha-1), with water limited conditions found to reduce seed oil content by ca. 1.5% among lines. Under both well-watered and water limited conditions, highest biological yield (14003 and 11238 kg ha-1, respectively) and lowest harvest index (6.9% and 6.1%) were detected in G3 genotype. Based on this experiment, it is could be concluded that under well and limited irrigation, high seed yield and oil yield was achieved in G23, while seed oil concentration did not change remarkably by stress conditions.