Cucurbit Genetics Cooperative Report 2:23 (article 14) 1979
Varietal Differences in Growth of Melon (Cucumis melo L.) at Low Temperature
Station d'Amélioration des Plantes Maraîchères, I.N.R.A. Domaine Saint Maurice, 84140 Montfavet-Avignon, France
Melon is known as requiring high temperatures for a good growth, but we did not know differences in varietal reaction occur at low temperature.
First, we studied the action of root temperature. For that, young plants of four melon cultivars were cultivated in nutrient solution, the temperature at the root level being constant and equal to 12°C, 15°C, 18°C, and 21°C. The experiment was conducted twice, in May 1976 and in February 1977.
When root temperature was maintained at 12°C, growth was very poor, especially in 1977 in a period of weak radiation. At this temperature, we observed some differences in varietal reaction. Yellowing of the foliage occurred on 'Persian-Small Type' followed by a partial wilting of the plants while 'Vedrantais' remained green and healthy. Growth of the 'Persian-Small Type' was weakened by low temperature more than growth of 'Vedrantais'.
From these tests, we concluded that varieties do not react similarly when grown in nutrient solution with a low temperature. Differences are more pronounced when global radiation is low.
Later, we tested varietal reactions of 31 lines in natural cold conditions, a non-heated plastic greenhouse. After several days where mean temperature was below 15°C, we observed wilt, then necrosis, and some plants died. Rate of new leaf emergence was lessened. These various symptoms were correlated. Statistical analysis shows that significant varietal differences occurred. 'Persian-Small Type' was the least resistant variety for all the characters studied. The most resistant lines tested were 'Freeman's Cucumber', 'Shiroubi Okayama', 'Savor', 'Sucrin de Tours', and PI 136173.