Air and root medium temperature and the rooting of chrysanthemum and rose cuttings

Cuttings of the chrysanthemum cultivar 'Horim' and rose cultivar 'Garnette' were rooted at 21°C, 24°C, 27°C root temperature in a factorial combination with 15°C, 18°C and 21°C air temperature. In each of the air and root temperatures, rose cuttings from different positions of the flower shoot were rooted. The effects of air and root temperatures and their interactions on root formation of chrysanthemum and rose cuttings were studied. Increasing the air temperature from 15°C to 21°C accelerated rooting and distinctly increased the number of roots per cutting on both plants. Higher root temperatures (24°C, 27°C) had a favorable influence on the rate of the rooting process but did not enhance the number of formed roots. Increasing both temperatures significantly increased the growth of the roots and their fresh and dry weight. An adverse effect of the root temperature was noticed on the breaking and growth of rose buds. Increasing the temperature from 21°C to 27°C strongly decreased the percentage of breaking buds and their growth. The results are discussed from the point of view of the influence air temperature on the contents of growth substances in the cuttings.