Effect of Water Deficit on Soil Variability, Plot size, Shape and Number of Replications for Chickpea

摘要

Two uniformity trials were undertaken on chickpea cv. Giza 159 during the winter seasons of 2004/2005 and 2005/2006, at the Experimental Farm of Faculty of Agriculture, Suez Canal University, Ismailia, Egypt. The study was designed to estimate the soil variability, optimum plot size, shape and adequate number of replications for chickpea under normal and water stress environments. The experimental area for each trail consisted of 800 basic units (1×1 m). Seed yield in grams was determined for each basic unit. Yield values from adjacent basic units were combined to obtain the combinations of different plot sizes and shapes for each trail.rnEstimates of soil heterogeneity (b) were 0.397 and 0.541 in the first season as well as 0.461 and 0.713 in the second season for normal and water stress conditions. The variance per basic unit area (V_x) and coefficient of variability (CV) decreased as plot size increased in both water regimes and seasons. The adequate plot size was found to be 5 - 8 m~2 for normal irrigation and 8 - 10 m~2 for water stress using maximum curvature and comparable variance methods. In respect of plot shape, long narrow plots were effective in reducing the variance per unit area and the coefficient of variability. The standard errors decreased as number of replications or plot size increased but the rate of decrease becomes negligible as number of replications exceeded 6 to 7 in both water regimes.