The Effect of Temperature on Development and Dry-matter Accumulation of Vicia faba Seeds

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Abstract
Vicia faba plants were grown at 16 °C and the temperature raised to 21 or to 26 °C, 51 d post anthesis (p.a.). Temperature increase accelerated pod and seed development, stimulated dry-matter accumulation, starch and protein synthesis. However, the duration of dry-matter accumulation of seeds was shortened, resulting in a decrease of final seed weight. The effect of temperature on storage capacity (determined by cell number and cell size) was also investigated. Formation of new cells in the layer under the epidermis continued for a much longer period than previously has been described in the literature. At all stages of development cotyledons contained young and small cells with small nuclei at the outside and they became larger and older towards the centre of the cotyledon. Cells at the centre were only able to divide at an early stage of seed development up to day 59 p.a. Thereafter cell division occurred mainly in the first cell layer under the epidermis up to 63–67 d p.a. Nuclear counts of macerated cotyledon cells did not show an effect of temperature on the number of cells. It has, however, been questioned if this method was suitable to measure accurately the number of cells at the last stages of seed development. The rate of cell expansion was stimulated by higher temperatures but the duration of expansion was shortened and the final size of cells was not affected by the different temperature treatments. Senescence of the pod wall was accelerated at higher temperatures and it is possible that transport of sucrose from the pod wall to the seeds terminated earlier than at lower temperatures. This may have resulted in an inhibition of cell formation at the periphery of the cotyledons and in an inhibition of starch and protein synthesis.