evaluation of the effect of closed and perforated plastic tunnel microclimates on leaf expansion and phenological stages of cucumbers

cucumbers grown under open air conditions, encounters chilling damages, during cold seasons. plastic tunnels provide suitable heat environment for growing cucumber. the objective of this research was to evaluate cucumber phonological stages and leaf area expansion within three different plastic tunnel microclimates to moderate air temperature and air humidity. three microclimates including 1. completely closed plastic tunnel (mc), 2. perforated plastic tunnel (mp10), with 100 holes (10 mm in diameter) per m2, and 3. perforated plastic tunnel (mp15), with 100 holes (15 mm in diameter) per m2, as experimental treatments, were employed using a complete block design with three replications. by employing snk post-hoc, the results showed a significant difference for growth degree-days and leaf area expansion between tunnels. within mc tunnel, phenological stages always occurred ahead of other treatments. cucumber leaf numbers and secondary side shoot within mc were significantly higher than perforated plastic ones. late in the season leaf area of mp10 reached mc's. in conclusion, mp10 microclimate with relevant microclimate condition could be a good option for early cucumber production.