Leaf area development of micropropagated potato plants: effects of leaf area of individual plants on logistic curve parameters and correlations among these parameters

Abstract

Leaf area increase of individual, in vitro produced potato plantlets was analysed over three growth phases: in vitro normalisation (3 weeks, 17 or 23°C), transplant production (2 weeks. 18/12 or 26/20°C) and tuber production (6 weeks. 18/12 or 26/20°C). In each phase, initial leaf area (ILA) and final leaf area (FLA) of logistically growing plants were related to parameters describing logistic growth (leaf area = A+C/(1+-exp((-Bxtt-M))); A: fitted minimum leaf area, B: fitted initial relative rate of increase, C: fitted maximum increment, M: fitted midpoint, MI: maximum rate of increase at M, MI = BxC/4). Higher ILA was associated with higher FLA during normalisation and transplant production, but not consistently during tuber production. During normalisation, higher ILA led to higher A, C and MI-values, and at 23°C also to higher B and earlier M. During transplant production, higher ILA was associated with higher C.During normalisation, leaf area increase of plants with higher FLAs was characterised by higher A, C and MI-values, and at 23°C also by earlier M. During transplant production, higher FLAs were associated with higher C and MI-values, and at 18/12°C also with higher A. During tuber production, higher FLAs were associated with higher C, M and MI-values.Correlations among parameters characterising logistic growth were of physiological origin, mathematical origin, or resulted from the actual shape of the logistic curve. A and B were positively correlated, likely because clearer S-shaped curves result in higher values of both. Both parameters usually were positively correlated with MI, likely because MI is a function of B, whereas A was correlated to B. Physiologically relevant correlations were found between M and C in the tuber production phase.