Pumpkin | Fruit Yield | Seed Oil | Heterosis | Potence Ratio | Combining Ability | Correlation

Alicylic acid (SA) and Ca2+ regulate the physiological and biochemical mechanisms in plants. A factorial experiment was designed to evaluate the effect of foliar application of calcium chloride (0, 10, 20, 30 or 40 mM) and salicylic acid (0, 0.5, 1, 1.5 or 2 mM) on the vegetative growth of romaine lettuce cv. Balady during 2013/2014 and 2014/2015 seasons at the Experimental Farm of Horticulture Department, Faculty of Agriculture, Ain Shams University, Qalubia Governorate, Egypt. Results clearly indicated positive effects of foliar applications of calcium chloride and salicylic acid either alone or in combination on lettuce growth, productivity and some physiological parameters. Foliar application of calcium chloride at 20 mM significantly increased vegetative growth parameters (plant length, head diameter, fresh and dry weights of head, number of leaves/head, average leaf area and leaf area index), chlorophyll (a, b, and total), leaf relative water content, leaf membrane stability index, and macro- and micro-nutrients. Moreover, salicylic acid spraying at 1.5 mM significantly gave the highest significant values of all aforementioned parameters. Exogenous applications of calcium chloride and salicylic acid either alone or in combination reduced nitrate accumulation in the leaves. Spraying of calcium chloride at 20 mM with salicylic acid at 1.5 mM was the most effective treatment which can be used as an applicable practice in romaine lettuce cv. Balady cultivation.

Faced with the scarceness of water resources and climate changes, drought is undoubtedly one of the most important abiotic stresses limiting the growth and productivity of plants especially in the arid and semi-arid areas. The uses of soil amendments like biochar and superabsorbent polymer, which characterized by enhancing water holding capacity and improving soil physical properties, become more important in these areas. A lysimeter experiment with sandy soil in a completely randomized design was conducted to study the effect of biochar or/and superabsorbent polymer on the growth and productivity of green pea cv. Master B under full irrigation (100% of WR) and water deficit (75% of WR) conditions during 2015/2016 and 2016/2017 seasons at the Experimental Research Farm, Horticulture Department, Faculty of Agriculture, Ain Shams University, Qalyubia Governorate, Egypt. Results revealed that lowering irrigation level to 75% of water requirements led to significant decreases in vegetative growth parameters, SPAD readings, leaf relative water content, leaf nutrients and pod yield components compared with the full irrigation. Adding biochar or/and superabsorbent polymer significantly increased the aforementioned characters under both full irrigation and water deficit conditions. Application of biochar with superabsorbent polymer was the most efficient to alleviate the deleterious effects of water deficit on green peas cultivation in sandy soils. In conclusion, applying biochar (1% w/w) with superabsorbent polymer (0.7% w/w) might be a promising novel approach to improve sandy soils characteristics and help green pea cultivation in these soils which are characterized by a low water holding capacity and low fertility.