Four local sesame varieties were tested at three plant populations. Increase in plant density increased seed yield, which was positively related to number of pods per plant, seeds per pod, 1000-seed weight, heights of main stems and numbers of nodes per plant. Changes in soil moisture did not affect relative turgidity, whereas stomatal openness decreased as the irrigation interval became longer.

Availability of soil water was investigated and the methods of determining the lower limit of availability by biotic and standard 15-bar pressure were compared. Greenhouse-grown sunflower and okra were the test crops for the biotic method. The pressure membrane equipment was used for standard 15-bar moisture determination. Okra and sunflower took up water beyond the standard 15-bar tension, thus lowering the moisture content at moderate wilting below the generally accepted values. In topsoil okra wilted at very high tensions, but at somewhat lower tensions in subsoil samples, unlike sunflower which wilted at higher tensions in subsoil samples. An equation is given which may be used to estimate the moisture content at the moderate wilting point of plants with known wilting tensions.

The effects of three irrigation regimes on growth, yield and quality of cotton were investigated for two seasons in relation to earliness, quality and water-use efficiency, expressed as m. of water/kg. cotton produced. Light irrigations of cotton, at 75 mm. per irrigation every ten days, were economically better than the traditionally-accepted practice of irrigating every 14 days, and markedly better than prolonging the irrigation cycle to 20 days, mainly due to increased market value of the crop. The results also showed that irrigation intervals of 20 days, besides depressing yield, had a deleterious effect on fibre strength, though the different water regimes did not seem to affect other quality tests.