Seed Quality-Related Traits Influence Germination of Helianthus annuus L. Grown Under Three Levels of Water Supply

In order to select a suitable sunflower genotype with a high germination rate and germination speed under controlled field conditions, a selection program was launched. The effect of seed quality-related traits on the emergence time, germination percentage (G%), and germination index (GI) using three water regimes (rainfed, 50% water supply, 100% water supply) was assessed for six lines selected from an adapted sunflower population: C₈.₃.₁.₂ (Line1), 64A71 (Line 2), C₇.₃.₂.₂ (Line 3), C₁.₃.₁.₁ (Line 4), C₅.₂.₃.₂ (Line 5), and C₃₁.₁.₁.₂ (Line 6). Total seed crude protein (SCP), seed oil content (SOL), kernel-grain ratio (KGR), hull-kernel ratio (HKR), seed length:width ratio (LWR), and 100-seed weight (HSW) were assessed. Genotype and water regime independently affected G%, which ranged from 31%–72%, 39%–96%, and 35%–89% for rainfed, 50% water, and 100% water regimes, respectively. All lines showed the highest G% at 50% water supply except for C₇.₃.₂.₂. Except for C₇.₃.₂.₂ and C₁.₃.₁.₁, G% decreased when the water level increased. There was a significant positive correlation between KGR and G% in 50% and 100% regimes (r = 0.63, r = 0.59, respectively; P < 0.01). However, the association was significantly negative between HKR and G% in 50% and 100% regimes (r = −0.47, r = −0.63, respectively; P < 0.01). The G% in the 100% regime was also significantly and positively correlated with SCP (r = 0.49; P < 0.05). Compared with the 50% and 100% regimes, G% in the rainfed treatment was not correlated with any seed-related traits. The HKR, KGR, and SCP can be considered to be the most selective criteria since they show a significant correlation with the 50% and 100% water regimes. In conclusion, 50% water supply is the most adapted regime for most of the sunflower genotypes examined in our study.