Development of micropropagated potato plants over three phases of growth as affected by temperature in different phases

Abstract

To assess (after)effects of temperature on plant development, in vitro potato plantlets produced at 17 or 23 °C (normalisation phase, 3 weeks) were planted into soil in growth chambers at 18/12 or 26/20°C (transplant production phase, 2 weeks), and transplanted to glasshouses at 18/12 or 26/20°C (tuber production phase, 6 weeks). The latter phase commonly takes place in the field. Transition from one phase to another, especially from in vitro to in vivo conditions, greatly increased leaf growth and to a smaller extent stem growth. Within a phase, higher temperature stimulated vegetative growth, but delayed tuber formation and reduced tuber yields, harvest index (HI) and tuber dry matter concentration. Temperature during tuber production was more important for high yield than temperatures during earlier phases. Normalisation and transplant production temperatures nevertheless showed after-effects in later phases. Lower normalisation temperatures advanced plant development: they increased vegetative growth in subsequent phases and finally increased fresh tuber yield and HI. This could have yield advantages at locations where field production seasons are short. Lower transplant production temperatures reduced vegetative growth in the next phase, but enhanced early tuber production. Finally they increased tuber dry weight and HI when tuber production temperatures were high. This may increase yield at locations where field conditions delay tuber formation.