In a variety test, performed at the Texas A&M University Research Station, College Station, TX, four upland cotton cultivars were examined in two planting dates. Cultivars were Acala SJ-2, TAMCOT SP 37 H, B.D.-19 and B.D.-12. During the growing season, the cultivars were monitored by sampling the plants once a week, according to the empirical model routine. Leaves and stems were chemically analyzed for macronutrient elements. A comparison of the developmental behavior was made between the empirical model and the "COMAX-GOSSYM" simulation model. Yield and fiber quality were determined at the end of the season. The possible causes for a difference (c.a. 50%) in lint yield of the "Acala" types in Texas and Isreal are discussed.