TEMPERATURE CONTROLS THE RATE OF DEVELOPMENT IN SHORT-DAY AND LONG-DAY PLANTS DURING VEGETATIVE STAGE OF ONTOGENESIS

The work was conducted to study the effects of constant and alternating daily temperatures using DIF from –20 to +20 ^oС and the average temperature from 15 to 35°С on plant developmental rate under 8, 12 and 16 hour photoperiod. Model plants were short-day plant (SDP) soybean (Glycine max L. Merr.), long-day plant (LDP) wheat (Triticum aestivum L.), and neutral day plant (NDP) cucumber (Cucumis sativus L.).
It was shown that plants affected by temperature gradient may pass ontogenetic phases at smaller temperature sum, provided average daily temperature is lower than optimum. Data indicate that development of plants under conditions of gradient diurnal temperatures can be accelerated by DIF. This may have an important adaptive role, in particular for plants in the North. It also indicates that when calculating the sum of effective temperatures, one has to take into account whether temperature is constant or not.

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