| Abstract: | Baldy, P. 1986. Comparison between growth chamber and field-grownZea mays plants for photosynthetic carboxylase activities andother physiological characteristics with respect to leaf position.—J.exp. Bot. 37: 309–314. The lengths and fresh weights of leaves, and the amounts ofchlorophyll and protein per leaf, were higher in maize grownin a controlled environment than for field-grown maize harvestedat a similar stage of growth with the seventh leaf just emerging.However, the fresh weight and chlorophyll per unit leaf areawere not different and more protein was present per Unit leafarea in maize cultivated in the field, particularly in the 4thleaf. Except in the seventh leaf the youngest present, the PEP carboxylaseactivity was 2-fold higher in field-grown maize than in plantsfrom the controlled environment. The RuBP carboxylase activitywas not significantly affected by growth conditions. The maximumactivities of the carboxylases were found in the 5th leaf formaize grown in the controlled environment and the 4th leaf forfield maize; in these two leaves the ratios of the PEP: RuBPcarboxylasc activities were 3·0 and 4·4 respectively. The results are used to justify the choice of the fully expanded4th leaf of l9-d-old plants grown in a controlled environmentfor studies of the enzymes involved in the photosynthetic carbonmetabolism of this C4 plant. Key words: Growth conditions, PEP carboxylase/RuBP carboxylase activity ratio, Zea mays leaf position |
