Response of Sweet Granadilla to Temperature and Thermal Lethal
Date Issued
2009
Date
2009
Author(s)
Chen, Li-An
Abstract
There are a few problems in passion fruit industry of Taiwan such as small cultivating area, high cultural cost, single cultivar, limited market and serious virus disease. There is desperate need to introduce new varieties to break through the difficulties. Passiflora ligularis (sweet granadilla) is a potentially edible passion fruit which has several good characters such as big fruit shape, unique taste, low acidity and high yield which make it suitable for fresh fruit use, especially that compatriots prefer sweeter tastes. After observation for three years, we concluded that most seedlings and cutting plantlets can’t survive because of the summer heat in lowland of Taiwan, but three seedlings survived for two summers which indicated that P. ligularis might have the potential to overcome its obstacle through breeding or cultivation technique and increase the diversity of edible passion fruits in Taiwan. Through the experiments, we now somehow have an overall idea about sweet granadilla thermal lethal phenomenon. Seedlings planting treated with day/night temperature 35/30ºC, 30/25ºC, 25/20ºC , 20/15ºC and 15/10ºC, respectively, all of the plants under 35/30ºC, and 42％ of plants under 30/25ºC were dead within 5 weeks. The growth situation is best under 25/20ºC. Repeat the experiment with cuttings under day/night temperature 30/25ºC, 25/20ºC, 20/15ºC, 15/10ºC condition. After 7 weeks, the death rate of plants under 30/25ºC goes to 50％, and the growth situation is better under 20/15ºC. Treated normal cutting plantlets, grafting plantlets and the ambiguous heat-less sensitive cutting plantlets under day/night temperature 30/25ºC, 20/15ºC and 3 root temperature which were 20℃, 25℃, 30℃, to understand the lethal thermal tolerant of top and root. At summer experiment, treated for 10 weeks, the death rate of 30/25ºC was 67％, and at winter time, after 7 weeks of treatment, the death rate of 30/25ºC was 59％. And the death rate of 20/15ºC was 6％ and 0％, respectively. Under 30℃ root zone temperature (RZT), the death rate were 50％ and 33％, respectively, 33％ and 28％ under 25℃ RZT, 25％ and 0％ under 20℃ RZT. The death rate for cuttings for 10 weeks at summer and 7 weeks at winter was 59％and 22％, 33％ and 17％ for the ambiguous heat-less sensitive cuttings ,and 17％ and 27％ for grafting plantlets. No matter with which air temperature, the growth was better under low RZT, and there was small difference between the materials. To analyze the leaf and root Fe, Mn, Zn content, and the total contents in leaves and root were higher under lower air temp. But the concentration for Mn and Zn were higher in chlorosis leaves than in normal leaves. To test the membrane thermostability (MTS) of sweet granadilla leaves. The MTS of the upper chlorosis type leaves that were induced by high air temp were significantly worse than the elder normal leaves. To identify the leaves into 4 typical grades under heat stress, MTS showed no significant difference between the normal type and the intermediate. And the MTS of semi-chlorosis type was under 60%, for the chlorosis type was eventually less than 10%, both significantly lower. To lower the RZT was helpful for sweet granadilla to face high air temp but still unable to overcome heat stress, and the ambiguous heat-less sensitive cutting plantlets and the grafting plantlets showed better tolerance than the cuttings, however, none of them were growing normally without chlorosis under high air temperature.
Subjects
sweet granadilla
temperature
lethal
Type
thesis
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