Optimizing Planting Date Enhances Growth and Flowering of Broad Bean (Vicia faba L.) under Mediterranean Greenhouse Conditions

Abstract

This study evaluated the influence of planting date on vegetative growth and flowering performance of broad bean (Vicia faba L.) under semi-controlled greenhouse conditions in Sirte, Libya. A completely randomized design (CRD) was used with three sowing dates (15 February, 15 March, and 15 April 2024). Although the experiment included a limited number of replicates (n = 3), strict environmental control and uniform management practices were applied to enhance data reliability. Average greenhouse temperatures varied across planting periods, ranging from 12–18 °C in February, 15–25 °C in March, and 20–32 °C in April, thereby exposing plants to progressively increasing thermal conditions. These temperature differences provided a practical framework for evaluating plant responses to moderate and elevated temperature regimes. Results showed that planting date significantly affected plant growth and reproductive performance. Two-way ANOVA revealed significant effects on stem length (F = 18.4), leaf number (F = 12.7), and number of flowers (F = 21.5) (p < 0.05). Early planting (February) enhanced vegetative growth, as reflected by increased leaf production and expansion, whereas mid-March planting resulted in the highest flowering performance (13.5 ± 1.2 flowers plant⁻¹). In contrast, April planting, which coincided with higher temperature ranges exceeding 30 °C, led to significant reductions in flowering (6.0 ± 1.5 flowers plant⁻¹), suggesting the onset of heat-induced reproductive limitations rather than optimal growth conditions. Overall, the findings demonstrate that planting date influences the balance between vegetative and reproductive development in broad bean by altering plant exposure to temperature conditions. Under Mediterranean greenhouse environments, mid-March planting provided the most favorable thermal window for optimizing reproductive performance.