Productivity and Quality of Lima Bean Grown in Sandy Soil as Affected by Plant Densities and NPK Applications

Two field experiment were carried out during 2008 and 2009 summer seasons (5(th) March), at the experimental farm of Faculty of Agriculture, Sohag University Egypt, to investigate the influence of three plant densities (17.1, 11.4 and 9.1 plant/m(2)) and four NPK equations i.e., 119.6-55.3-59.5, 159.5-73.8-119.0, 199.3-92.2-178.5 and 239.2-110.7-238.0 Kg N-P-K/ha on productivity and quality of lima bean cv. 'Raio de sol' grown in sandy soil. The obtained results showed that, plant population densities significantly affected vegetative growth parameters i.e., (plant height and number of branches/plant); yield and its components expressed as number of pods/plant, pod length, pod width, number of seeds/pod, weight of 100-seeds and total seeds yield as well as quality characteristics i.e., protein, phosphorus and potassium percentages as well as vitamin B1. However, the medium plant densities (11.4 plant/m(2)) resulted in the highest values of pod length cm, weight of 100 seeds, and total seeds yield, in both seasons. Increasing NPK rates significantly increased all studied characteristics in the two experimental seasons. Moreover, the plants received the highest rate (239.2-110.7-238.0 Kg N-P-K/ha) gave the highest values for all studied characteristics as compared to other NPK equations. The interaction between the two studied factors (plant densities and NPK equations) significantly affected vegetative growth criteria, seed yield and its components as well as quality characteristics. Meanwhile, the combinations between medium plant density and NPK application rate (11.4 plant/m(2) and 199.3-92.2-178.5 Kg N-P-K/ha) recorded the highest values for pod length, number of seeds/pod, weight of 100 seeds, and total seeds yield as well as all quality characteristics in both seasons.