Effects Of Ca²⁺ Treatment On Heat Tolerance Of Different Rosa Hybrida Varieties

Rosa hybrid, with a plants, which belongs to Rosoideae Focke in Rosa in Ruttan shrubs, can be used as a kind of vertical afforestation plants. The high temperature has a great effect on R. chinensis, which leads to many flowers of that come out less, have lower qualities and get into the half-sleeping movement. In summer the consistent high temperature is the main limited fact that influences the blossom and quality. Therefore, it is meaningful to improve the blossom quality and extend the flowering by taking effective measure to reduce the damage that the high temperature cause to Rosa hybrid. In this experiment, biennial leaves from Rosa hybrid plants were dealt with different concentrations of calcium chloride and corresponding physiological indices were determined under the high-temperature stress. The experiment provides some certain practical support for the idea that the stress resistance of Rosa hybrid can be strengthen with the calcium inducement. The results of the study are as following:1. The heat-resistance.’Rosa hybrida cv. Parkirerktor Riggers’ does better than Rosa hybrida cv. Spectra in heat-resistance, then comes’Rosa hybrida cv.Westerland, and finally ’Rosa hybrida cv. Carefree Wonder Climbing.’Rosa hybrida cv. Carefree Wonder Climbing is quite different from the other plants.2. Under the high temperature, the damage to the cell membrane of the Rosa hybrid, which is not heat tolerant, are worse than that of Rosa hybrid in the therm-resistant cultivar. Another point is that the conductivity went up in the same way. According to the corresponding physiological indices we get, we find that the conductivity can show the effect of heat-resistance in Rosa hybrid best. With prolonging of heat stress time, the conductivity went up, and the amount of proline and soluble proteins increased, but the amount of soluble proteins reduced in heat-sensitive varieties of Rosa hybrid.3. Proper concentrations of calcium chloride can reduce the damage caused by high temperature to Rosa hybrid such as ’Rosa hybrida cv. Spectrd,’Rosa hybrida cv. Parkirerktor Riggers’,’Rosa hybrida cv. Westerland and’Rosa hybrida cv. Carefree Wonder Climbing. In this way, the sharply increasing of conductivity could be alleviated, and the membrane lipid peroxidation was reduced to some extent. At the same time, the amount of proline was increased to maintain a relatively high level so as to strengthen the cell water-holding ability and improve the plants’heat-resistance.4. Generally, at the temperature of40℃, under the high-temperature stress, the effect on improving Rosa hybrida’s heat-resistance by keeping spraying12mmol/L CaCl2for four days is better than that by keeping spraying10mmol/L CaCl2for seven days. The difference between the two is not clear, while it is more clearly to see the difference by spraying8mmol/L CaCl2(P<0.01).5. At the temperature of45℃, under high-temperature stress, it has a better effect on improving the Rosa hybrida’s heat-resistance by keeping spraying12mmol/L CaCl2for six days.The effect is more clearly than that by spraying8mmol/L CaCl2and10mmol/L CaCl2(P<0.01).6. When the concentration of CaCl2is beyond15%, the injuries, caused by spraying CaCl2for ten days, happen to the plants and the effect of heat-resistance get worse. This is probably related to the excessive spraying. It shows that the best effect is the solution of10mmol/L CaCl2for five days which can effectively reduce the damage caused by high temperature.