SUMMARYAn experiment was conducted during the 1978/79 summer at the Central Cotton Research Institute, Multan-Pakistan to evaluate the crop production patterns of two cultivars of cotton (G. hirsutum L.) differing in their reaction to heat-induced sterility. Boll set in variety ST3 amounted to 7.7% of the total fruiting points, from flowers opening during the hottest months of June, July and early August, while almost all the fruiting points produced by cultivar B557 during the same period were shed and no bolls were set. Of the flowers examined during July, 83.3% in B557 contained non-dehiscent anthers against 6.7% in ST3.

Seed priming is considered as an important component that results in early establishment of crop seedling. Thus, the effect of seed priming with iron (Fe) and zinc (Zn) on growth and yield components of groundnut (cv. BARI-2011) was evaluated by using different doses of Fe (0.1% and 0.3%) and Zn (0.5% and 1.0%) in RCBD design with two factors factorial arrangement having three replications. The crop was grown in April, 2016 at the Research Farm of PMASArid Agriculture University, Rawalpindi, (Pothowar Pleatue) Punjab, Pakistan. Data revealed that plant height and number of plants were highest at 0.3% Fe in combination with 1.0% Zn. Similarly, numerical values for all measured yield components i.e., number of pods plant -1 , kernel weight (kg ha -1 ), 100 kernel weight (g), pod yield (kg ha -1 ), biological yield (kg ha -1 ), harvest index (HI) and shelling percentage were significantly higher at 0.3% Fe in combination with 1.0% Zn as compared to the control. The control plot resulted in the lowest values for all the parameters studied. It can be inferred from the results that seed priming at the rate of 0.3% Fe in combination with 1% Zn is recommended for obtaining higher yield of groundnut.

The effects of four cropping systems on water-stable aggregation were compared. Two methods of wetting the soil, (1) by capillarity and (2) under vacuum prior to wet-sieving, were also compared. Various soil constituents were determined to assess their roles in the promotion of granulation and stability. Water-stable aggregation in grassland was significantly higher than in the other three long-term rotations, corn once in 9 years, continuous wheat, and 4 years alfalfa in 10 years. No significant differences in water-stable aggregation were found among the other three rotations.Wetting the soil by capillarity was judged to give a better index of soil aggregate stability than wetting under vacuum. Organic carbon and stable aggregation were positively correlated in the grassland soil and in the soil of the cultural treatments combined over all depths, suggesting an important role of organic matter in stabilization of soil aggregates. It is pointed out, however, that in cultivated soils the cultivation or the type of root system of the crops may override the influence of the organic carbon. Total soluble salts were positively correlated with aggregation in a few treatments.

The consumptive use of water by cotton (G. hirsutum L.) variety 149F, sown at three dates, was calculated using Penman Et x crop factor method. The earlier the sowing date the more water evapotranspired, mainly due to differences in the length of the growing season and the amount by which it coincided with the monsoonal depression of potential evapotranspiration. An example is given of calculating the irrigation requirements of a mid-June sown cotton, accounting for average rainfall, showing that the water requirements of cotton during the early stages may be adequately met by the establishment irrigation and rains during July. Examples are cited to show that a charged profile at the beginning of the season may sustain good growth and produce satisfactory yield.The actual water use by crops varies greatly between seasons and locations, depending mainly on the evaporative condition of the atmosphere and the crop characteristics that determine ground cover and roughness of the canopy. Several direct and indirect methods for determining crop water requirements are reported in the literature (Israelson and Hansen, 1962;Hudson, 1965;Chang, 1968). The indirect methods include the use of different evaporation pans and empirical formulae to estimate evaporation from an open water surface, or potential evapotranspiration from a reference crop. These estimates are then related to actual water use by various constants, in a general relation represented by:where ET= Actual evapotranspiration or consumptive use, E = Potential evapotranspiration (evaporation from a short green crop, actively growing, completely covering the ground and adequately supplied with water), E o = Evaporation from an open water surface, and K = Crop or pan factor.The Penman method (Penman, 1948) which estimates E o , and its modification (Penman, 1956), which estimates E t , are widely used to calculate crop water requirements in both temperate and tropical climates (Chang, 1968;Farbrother, 1970). The Penman formula, combining a radiation energy term and an aerodynamic component, requires the following meteorological data; t This work has been carried out under UNDP/FAO Project PAK/73/026.

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