Heat Stress Leads to Poor Fruiting Mainly Due to Inferior Pollen Viability and Reduces Shoot Photosystem II Efficiency in “Da Hong” Pitaya

High summer temperatures (day/night: 40 °C/30 °C) are known to cause poor fruiting, reduced fruit/seed weight, and delayed fruit development in the “Da Hong” red-fleshed pitaya (Hylocereus polyrhizus); however, the mechanisms of these effects are unknown. This study examined how high temperature (HT...

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Published inAgronomy (Basel) Vol. 12; no. 1; p. 225
Main Authors Chu, Yu-Chun, Chang, Jer-Chia
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.01.2022
Subjects
Cross-pollination
Efficiency
Fertility
Fertilization
Flowers & plants
Fruit set
Fruits
Germination
Heat stress
Heat tolerance
High temperature
high-temperature stress
Hylocereus
Photoinhibition
Photosystem II
pistil
Pollen
Pollination
Seeds
Shoots
stamen
Viability
Mexico
Vietnam
Israel
China
Taiwan
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Summary:High summer temperatures (day/night: 40 °C/30 °C) are known to cause poor fruiting, reduced fruit/seed weight, and delayed fruit development in the “Da Hong” red-fleshed pitaya (Hylocereus polyrhizus); however, the mechanisms of these effects are unknown. This study examined how high temperature (HT, 40 °C/30 °C) affects stamen and pistil fertility through pollination combinations and fruit set in “Da Hong” pitaya and evaluated photosystem II (PSII) efficiency in yellowed shoots (cladodes). The in-vitro pollen germination rate was significantly higher at optimal temperature (OT, 30 °C/20 °C) than at HT, which was also associated with a reduced flower length, poor fruit set, small fruit size, and low number of seeds after self-pollination. Meanwhile, fruit set and fruit development were remarkably improved by using the pollens taken from plants grown at OT and moderate temperature (MH, 35 °C/25 °C) after mutual cross pollination, indicating that the reduction in seed number caused by incomplete fertilization due to inferior pollen viability was the main cause of poor fruiting under HT rather than pistil or photoinhibition, although HT treatment was linked to reductions of PSII efficiency at both the adaxial and abaxial ends of shoots. The results suggested that pollen viability was most affected under HT stress; thus, yielding remarkably reduced fruiting.
ISSN:2073-4395
2073-4395
DOI:10.3390/agronomy12010225