Photo-sensitive and photo-insensitive cultivars of rice were grown in pot culture during wet (monsoon) and dry (winter) seasons to study diurnal and seasonal variations of organic and keto acid content and respiration rates of the leaves at different stages of growth.Organic acids accumulate with a large concentration of oxalic and tartaric acids in the photo-sensitive cultivar, Latisail in the dry, and in the photo-insensitive, IR-8 in wet seasons. Malic acid, being the most prominent, wasconcentrated in darkness and consumed largely in light in the following day. RQ valuesshow that diurnal variations which are highest in morning decline during day and rise again at night. © 1978 Annals of Botany Company.