Investigation of Proline, Chlorophyll and Carotenoids Changes Under Drought Stress in Some Onion (Allium Cepa L.) Cultivars

Drought is one of the major limitations for vegetable growth and productivity all over the World. In this study the effects of drought stress on proline, chlorophyll a/b, total chlorophyll and carotenoids were investigated in some onion (Allium cepa L.) cultivars (Kantartopu-3, Akgun-12 and Texas Early Grano) under the early plant growth phase.  Seeds were germinated in peat material and transferred to plastic pots after 21 days of sowing. The plants have been grown in vermiculite by “substrate culture” technique. Three different irrigation applications (pot/field capacity (PC) PC-90 (90% of PC), PC-70 (70% of PC), PC-40 (40% of PC) were tested under greenhouse conditions. After six weeks of transferring, leaf parts were isolated and studied for various indices. Irrigation rates affected significantly the all parameters of onion. The results indicated that drought increased accumulation of proline in onion seedlings, while decreased the content of chlorophyll and carotenoid.