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EFFECTS OF ONTOGENETIC STAGES, LEAF POSITION AND COLOUR RATING ON CO₂ ASSIMILATION IN PHASEOLUS VULGARIS L., UNDER FIELD CONDITIONS

G.H. JAMRO, G.S. POSYPANOV*, V.N. POSYPANOV AND T.P. KOBZVA

Abstract: CO₂ assimilation rate in beans (Phaseolus vulgaris L) was investigated under field conditions. The rate of CO₂ assimilation in leaves was significantly affected by ontogenetic stages, leaf position and their interactions. Maximum CO₂ assimilation rate (15.332 mg CO2/dm^-2 hr^-1 was recorded at flowering stage followed by budding whereas, among the leaf positions. the higher rate of (14.985 mg CO_2/dm^-2 hr^-1 was observed in upper leaves followed by central and lower leaves. Both leaf area and dry matter accumulation was higher at the pod forming stage, highest CO₂ assimilation was recorded in deep green leaves followed by light green and yellow leaves. CO₂ assimilation rate drastically reduced after pod formation as the case with dry matter accumulation and leaf area. CO₂ assimilation was maximum in upper as well as deep green leaves as compared to lower leaves with light green or yellow colouring.

Department of Agronomy, Sindh Agricultural Univeristy, Talldojam, Pakistan.

Department of Crop Production, Agric. Academy, Moscow, USSR.