Condensed flowering is a viable strategy for reliable canola yields in terminal drought-prone regions

Context Annual grain crops in winter rainfall-dominated Mediterranean climates are frequently exposed to terminal drought stress. This abrupt and often premature end of season intensifies competition to access resources between new flowers and maturing pods, leading to late-stage flower abortion and inefficient resource use. Aims To gain a deeper understanding of the relationship between reproductive organ development and yield formation, and to evaluate the impact of terminal drought stress on this dynamic process. Methods This study investigated the temporal and spatial distribution of flower and pod numbers, as well as yield formation, under different water regimes in both glasshouse and field experiments. Key results The results showed that in field conditions with terminal drought stress, the pod-to-flower ratio ranged from 30% to 45%, whereas in well-watered glasshouse conditions, it ranged from 48% to 65%. The flowering duration of canola genotypes spanned over 5–6 weeks, with the majority of seed yield derived from flowers that emerged within 3.5 weeks after the first flower opening. Terminal drought stress initiated at flowering further reduced the effective flowering period to ~3 weeks. Conclusions Canola genotypes with strong branching ability exhibited a shorter and more compact flowering period, resulting in fewer flowers per branch but fewer ineffective flowers on each inflorescence. This trait may be considered an adaptive strategy to optimize resource allocation and reduce the impact of environmental stress during reproduction. Implications These findings support the hypothesis that selecting canola genotypes with a more synchronized and condensed flowering period could enhance resource allocation towards pod development, providing a viable strategy to achieve reasonable yields under terminal drought stress in Mediterranean-type climates.