Effects of Soil Moisture Stress on Two Varieties of Upland Cotton in Israel II. The Northern Negev Region

Abstract

SUMMARYThe effects of moisture stress at various stages of development were studied on two varieties of cotton in the arid Negev region of Israel. Experiments over two years indicated that the stage at which moisture stress occurred determined its effect: when at the beginning of flowering, yield was considerably reduced; at the peak of flowering there was a less pronounced effect; and when stress occurred during boll development it had an effect in only one year, when reserves of moisture in the deep soil layers were low. Lint yield ranged from 380 kg./ha. without irrigation to 2150 kg./ha. with five irrigations. Effects on lint length and lint strength were also studied. Two physiological indices, stomatal aperture and refractive index of leaf sap, were used to determine the onset of moisture stress.