Vol. 73 No: 4

Title:
Mobilization of ¹⁴C-carbohydrate Reserves in Relation to Vegetative Growth and Inflorescence Development in June Bearing Strawberry Plants

Authors:
T. NISHIZAWA, Y. SHISHIDO and H. KUMAKURA

pp: 499-506

Abstract:
Single leaves of June-bearing strawberry plants (Fragaria × ananassa Duch. cv. Donner) were exposed to ¹⁴CO₂ at four growth stages from 6 September to 17 January and the mobilization of ¹⁴C-labelled reserves in relation to the plant growth after forcing was analysed. The dry mass of roots increased continuously from late summer (6 September) to the onset of forcing (24 January). Under forcing conditions, the dry mass of roots, soluble sugar and starch contents per roots decreased by 33%, 53% and 96%, respectively to full bloom stage (21 February) with a concomitant increase in the dry mass of inflorescences and new leaves. These results suggest that carbohydrate reserves, especially starch, accumulated in the previous growing season in the roots of June-bearing strawberry plants are mainly utilized for the initial vegetative growth and flowering. The accumulation rate of non-structural carbohydrates per roots was greater between 6 September and 12 October (17.5 mg per day) than between 25 November and 24 January (11.0 mg per day). However, when plants were exposed to ¹⁴CO₂ on 6 September and 12 October, the percentage distribution of ¹⁴C in each plant part changed little under forcing conditions and ¹⁴C distribution to non-structural carbohydrate fractions in the roots was minimal. On the other hand, when plants were exposed to ¹⁴CO₂ on 25 November and 24 January, ¹⁴C distribution to the roots decreased until full bloom under forcing conditions with a concomitant increase to the inflorescences and new leaves. Moreover, ¹⁴C distribution to the soluble sugar fractions in the roots also decreased. These results suggest that soluble sugars accumulated in the roots during late autumn to winter are mainly remobilized and utilized for the early growth of inflorescences and new leaves.

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