Studies on the drought and heat stress response of green bean ( Phaseolus vulgaris L.) varieties under phytotronic conditions

Abstract

The drought tolerance of six green-and yellow-podded varieties of green beans with different genetic backgrounds was tested in the phytotron. During the week prior to flowering the plants were kept either at 25/15°C (day/night) or at high temperature (30/15°C), with RH 75% and optimum water supplies. The heat-stressed plants were then divided into three groups; the first was returned to the control (25/15°C) chamber (RH 75%, optimum water supplies), while the second and third were exposed to mild drought stress (RH 60%, 50% water) at temperatures of 30/15°C and 35/25°C, respectively, throughout the flowering period.The varieties survived the short period of heat stress (30/15°C) prior to flowering without damage provided the temperature during flowering was reduced to 25/15°C and the water supplies were optimum. There was a sharp increase in the carotene level in the leaves of drought-stressed plants when the temperature during flowering was 30/15°C, but in plants exposed to 35/25°C during flowering the level dropped to near the control level. The latter group exhibited considerable damage, with a reduction in the water-soluble antioxidant content (ACW: antioxidant capacity of water-soluble substances) and the chlorophyll b content compared with the control.The antioxidant content (ACW) in the dark green leaves of green-podded varieties was lower than in the yellow-podded varieties and did not change as the result of drought and heat stress. In yellow-podded varieties, however, there was a significant decline in ACW in response to stress. Differences between the varieties in their adaptability to drought and heat could be detected as changes in the chlorophyll and carotene contents of the leaves even at 30/15°C.

Traits Related to Heat Stress in Phaseolus Species

“…The south part of Anatolia is predicted to be one of the most heat-affected regions by climate change. Yield reduction due to the heat stress effects was also similar to that which was explained by Nemeskéri, Remenyik [64], who showed that a decrease in yield is the result of the alteration of the reproductive organs, which are particularly affected by heat stress [20,26,[65][66][67]. The role of genes in the tolerance of bean species to heat stress is complex and can vary depending on the specific species and trait being examined.…”

Ecological drought resistance and adaptability of apple varieties

“…In the leaves of Idared, the ACW content was high, which is the sign of drought according to our earlier findings Ecological drought resistance and adaptability of apple varieties 119 (Nemeskéri et al 2008). In Jonagold, the leaves contain initially few ACL antioxidants, which increases during the drought (July 8 -23) and signalises the defence against high temperature and radiation (Table 5).…”

“…There are several methods serving the measurement of the water content of plants, but their efficacy depends on the purpose of the examination (Jones, 2007). In some vegetables, one week of drought may cause visible symptoms, leaves turn yellow and flowers abscise (Nemeskéri et al, 2008). In fruit trees, only utterly heavy drought of soil and of atmosphere may cause conspicuous symptoms, e.g.…”

Defence Strategies of Annual Plants Against Drought

“…Both the phytotron and field experiments illustrated that the yellow-podded green bean varieties respond to drought more sensitively than green-podded ones (Nemeskéri et al, 2008(Nemeskéri et al, , 2010. This was confirmed by the decrease in chlorophyll a and b components and the antioxidant capacity of water soluble (ACW) substances in the leaves of yellowpodded beans compared to the well-watered plants during flowering at severe drought stress in the phytotron, while there was not remarkable change in comparison with greenpodded ones (Table 2).…”