Temperature Drop as a Tool for Cold Tolerance Increment in Plants

Abstract

The experiments were conducted with Cucumis sativus L., Triticum aestivum L., Brassica capitata, Solanum tuberosum, Zea mays L. and Pisum sativum L. Temperature drop increased cold resistance in all studied species. Level of cold resistance under the drop treatments was much higher than under the constant low temperature. It remained at a higher level for a longer period during de-acclimation. It is concluded that DROP technology is a good way for successful transplantation of greenhouse agricultural and bedding plants in early spring.

Short term temperature drops do not enhance cold tolerance

“…6, 7), and thus is a useful tool to control plant height in production of transplants. The different method used here to evaluate cold resistance is probably the most likely explanation why the results of the present study contradict previous studies on effects of temperature drop on cold resistance (Markovskaya et al 2003;Sysoyeva et al 1999Sysoyeva et al , 2005. In the other studies cold tolerance has been evaluated by visual inspection of damage to cells after freezing of leaf discs for 5 min at temperatures in the range of -10 to -15°C.…”

“…In conclusion, a short diurnal temperature drop does not increase cold tolerance in intact plants of Arabidopsis, swede, white cabbage and pea, and could not substitute for a hardening period at constant low temperatures as suggested earlier on the basis of studies of leaf discs exposed to short-term freezing (Markovskaya et al 2003;Sysoyeva et al 1999Sysoyeva et al , 2005. Also, we found no pre-hardening effect of exposure of plants to a diurnal temperature drop (white cabbage or pea) or negative DIF (pea) over the entire growth period prior to hardening.…”

“…Three temperature regimes were tested for a cold hardening effect: (1) 6 days with constant low temperature, 6°C for swede, white cabbage and Arabidopsis and 12°C for pea, (2) 6 days with daily temperature drops the first 2 h of the light period, down to 6°C for swede, white cabbage and Arabidopsis and down to 12°C for pea and (3) daily temperature drops in the entire growth period. The temperature drop experiments were performed according to Sysoyeva et al (2005).…”

“…Earlier studies have reported that diurnal temperature drops of 2 h appear to result in improved cold tolerance as compared to constant low temperature (Markovskaya et al 2003;Sysoyeva et al 1999Sysoyeva et al , 2005. In these studies low temperature tolerance was assessed by observation of ultrastructural changes after 5 min exposure of leaf discs of various plant species such as cucumber (Cucumus sativus), pea (Pisum sativum) and white cabbage (Brassica oleracea var.…”

“…capitata) to freezing temperatures. It then also appeared that the cold tolerance was more persistent after temperature drop treatments than after exposure to constant low temperature (Markovskaya et al 2003;Sysoyeva et al 2005). As the vernalization signal in Brassica is broken by fluctuations between high and low temperatures (Heide 1970), it follows that exposure of transplants of Brassica to diurnal temperature drops might be a tool to achieve cold tolerance without stimulating bolting.…”