Abstract
This study was conducted to investigate the combined effect of soil gel-conditioner (Aquasorb) addition to calcareous sandy soil (Typic Torripsamments) and irrigation water quality on growth, productivity, and water use efficiency (WUE) of snap bean (Phaseolus vulgaris L.) plant grown under different water levels. The gel-conditioner was added to the soil surface (0-60 mm) at the following rates (C): 0.0, 0.3, 0.6, and 0.9% (on dry weight basis). Natural irrigation waters having the following electrical conductivities (EC(w)):0.45, 3.10, and 6.25 dS m(-1) were used at three irrigation levels (IL): 40, 60, and 80% of evaporation from a free water surface (E(v)).
Generally, the addition of the gel-conditioner promoted seeds germination; and increased plant height, leaf area index and dry matter of shoots and roots of snap bean. However, these parameters significantly decreased by increasing EC(w), but with no significant effect for IL. The number and fresh weight of snap bean pods (productivity) and water use efficiency were significantly enhanced with increasing C and reduced with increasing EC(w). On the other hand, the effect of irrigation level on the number and fresh weight of snap bean pods ranked as follows : 80 > 60 greater than or equal to 40% of E(v), whereas, this effect on WUE ranked as follows: 40 > 60 greater than or equal to 80% of E(v). Exponential relationships between WUE, C and IL were found with r > 0.934.
Based on technical considerations, the general recommendations might be obtained from this study are: the best rate of soil gel-conditioner (Aquasorb) was more than 0.3%, the suitable irrigation water quality was that of lower salinity (0.45 dS m(-1)); and the best irrigation level was the 60% of E(v).