A Greenhouse Study on Growth, Yield and Anatomical Parameters of Three Pea Cultivars: under Different Irrigation Levels and Growth Regulators

This experiment was carried out during the fall season 2009-2010 in the vegetable greenhouse, Horticulture Department, Dohuk University. Three pea cultivars namely Local crinkle, Local Smooth and Canadian were subjected to three irrigation levels where plant irrigated whenever 25, 50 or 75% of pot available water capacity were depleted, besides plants were sprayed with either 100mgl-1 gibberellic acid (GA3), 100mgl-1 indole-3-butyric acid (IBA), 2.5gl-1 micronutrient and distilled water as a check treatment. The objective was to evaluate the cultivar performance under adequate and inadequate irrigation during flowering, pod swelling and seed filling stages to find out which is the best, particularly under moderate and severe drought, besides that we intended to evaluate the possibility extent of boosting drought resistance of these cultivars by the aid of GA3, IBA and micronutrients. The obtained results exhibited that irrigating pea plants whenever 25% 0f pot available water capacity was depleted appeared to be the paramount irrigation treatment followed by that of 50% depletion and irrigation level of 75% are not advisable. 25% irrigation level manifested the highest leaf number per plant (26.33), plant height (141.15 cm), root dry weight (0.16g), flower number per plant (6.48), individual pod fresh weight (3.56g), seed number per pod (3.47), green pod yield per plant (14.53g), weight 100 seeds (23.02g), seed fresh weight per pod (1.44g), pericarp fresh weight (2.05g), aperture length of upper leaf stomata (4.38μm), stomata length of leaf lower surface (6.23 μm), stomata aperture length of leaf lower surface (4.75 μm), smallest vessel width (3.72 μm), protein content of dry seed (25.3%), GA3 (346.63 mgkg-1 dry seeds), and IAA (4109.72 mgkg-1 dry seeds). The best plant response was confined to these sprayed with micronutrient, then IBA and the lowest was GA3-treated pea. Pea sprayed by 2gl-1 micronutrients manifested the highest root dry weight (0.16g), leaf dry matter percentage (26.36%), stem dry matter percentage (35.77%), flower number per plant (6.43), pod number per plant (4.49), individual pod fresh weight (3.01g), seed number per pod (3.64), yield of fresh pods per plant (13.33g), total pod number per plant (4.11), weight of 100 seeds (23.51), fresh weight of pericarp (1.6g), stomata length at upper leaf surface (6.05μm), stomata length at lower leaf surface (6.6 μm), stomata width at lower leaf surface (3.78 μm), stomata aperture length at lower leaf surface (4.61 μm), stomata aperture width at lower leaf surface (2.38 μm), stomata population at lower and upper leaf surface (5971.88 and 3792.19 stomata mm-2, respectively), chlorophyll percentage out of gross pigments (40.05%), proline content (0.0062 μgg-1 dry seeds), ABA (713.31 mgkg-1 dry seeds) and IAA (3725.23 mgkg-1 dry seeds). Crinkle pea appeared to be the potent cultivar it gave the highest yield of green pod (14.6 gplant-1), plant height (119.8cm), leaf dry weight (0.27g), root dry weight (0.25g), leaf dry mater percentage (28.79%), stem dry matter percentage (36.39%), flower number (6.75), pod number per plant (4.62), individual pod dry weight (1.21g), pod fresh weight (2.72g), seed number per pod (2.95), pericap fresh weight (1.51g), dry pericarp (0.57g), upper leaf surface stomata width (3.7μm), upper leaf surface stomata length (6 μm), stomata aperture length of upper leaf surface (4.32 μm), stomata aperture width of upper leaf surface (2.2 μm), aperture length of lower leaf surface stomata (4.64 μm), aperture width of lower leaf surface stomata (2.32 μm), stomata length at lower leaf surface (6.4 μm), stomata width at lower leaf surface (3.96 μm), the widest and lowest vessels width (10.37 and 3.8μm, respectively), vessels number per bundle (12.46) and chlorophyll percentage related to gross pigments (34.74%). Local smooth comes next then the worst cultivar was Canadian. Therefore, crinkle was most drought resistant pea cultivar