Sizeable variation in total dry weight (TDW) production and reproductive to vegetative ratio (R/V's) of Pima and Egyptian cot­ton in favour of Pima cotton were observed. For Egyptian cotton the early maturing cultivars G.83 and G.85 were smaller in stature and produced less dry weight and were more efficient in squaring and boiling than G.80 and G.86 in all sampling occasions in the three en­vironments sampled. As for increasing the total biomass of Egyp­tian cotton, it would be necessary to increase the crop growth rate (CGR). For the duration of time that samples were collected in this study, higher values for the crop growth rate (CGR) and relative growth rate (RGR) of Pima cultivars versus Egyptian ones were de­tected, although differences did reach the significant level. There­fore, if the CGR of Egyptian cotton were improved along with im­proved partitioning of dry matter into reproductive organs, yield improvements would be realized. Maximum CGR was reached about two weeks earlier than the corresponding maximum LAI. This indicates that the expanded LA was over optimal for these cultivars. At LP planting system, maxi­mum LAI was reached about 2-3 weeks, earlier compared to CN planting system.Therefore useful variability for R/V would likely result in increased genetic advance for yield.