Continuous high and low temperature induced a decrease of photosynthetic activity and changes in the diurnal fluctuations of organic acids in Opuntia streptacantha

Abstract

Opuntia plants grow naturally in areas where temperatures are extreme and highly variable in the day during the entire year. These plants survive through different adaptations to respond to adverse environmental conditions. Despite this capability, it is unknown how CAM photosynthetic activity and growth in Opuntia plantlets is affected by constant heat or cold. Therefore, the main objective of this research was to evaluate the short-term effect of high (40°C) and low (4°C) continuous temperatures on the photosynthetic efficiency, the organic acid content (malic acid) and the relative growth rate (RGR) in seven-month-old Opuntia streptacantha plantlets during 5, 10, and 15 days. Chlorophyll fluorescence analysis allowed us to determine that high temperatures negatively impact the photosynthetic efficiency of O. streptacantha plantlets, which exhibited the lowest values of maximum quantum efficiency of the photosystem II (Fv/Fm = 52%, Fv/F0 = 85%), operational quantum yield of PS (ΦPSII = 65%) and relative electron transport rate (rETR = 65%), as well as highest values of basal fluorescence (F0 = 226%) during 15 days of treatment. Similarly, low temperatures decreased Fv/Fm (16%), Fv/F0 (50%), ΦPSII and rETR (16%). High temperatures also decreased nocturnal acidification in approximately 34–50%, whereas low temperatures increased it by 30–36%. Additionally, both continuous temperatures affected drastically diurnal consumption of malic acid, which was related to a significant RGR inhibition, where the specific photosynthetic structure area component was the most affected. Our results allowed determining that, despite the high tolerance to extreme temperatures described for Opuntia plants, young individuals of O. streptacantha suffered photosynthetic impairment that led to the inhibition of their growth. Thus, the main findings reported in this study can help to predict the potential impact of climatic change on the establishment and survival of succulent species of arid and semiarid regions of Mexico.

Relationship between weather conditions and the physicochemical characteristics of cladodes and mucilage from two cactus pear species

“…It was reported [34] that continuous high (40˚C) and low (4˚C) temperatures caused severe stress to young cactus pear cladodes, but in this case, the cactus pear plants grew in an orchard, and are subjected to ordinary day-night and seasonal weather which allow for acclimation and temperature adaption to occur [35]. In fact, it was found that in CAM plants, the optimal CO 2 fixation rates adapt to current growth temperatures.…”

Quality suitability regionalization analysis of Angelica sinensis in Gansu, China

“…sinensis is highly significant [ 17 ]. A moderately low temperature aids in the accumulation of organic acids [ 18 ], and longer periods of sunshine did not increase the volatile oil composition [ 19 ]. This may be related to the fact that A .…”

“…sinensi s is 6.5–8. Investigation found that the soil in the Gansu production area was alkaline; thus, the content of the index components negatively correlated with the soil pH [ 22 ].…”

“…The influence of temperature and moisture on the content of index components of A. sinensis is highly significant [17]. A moderately low temperature aids in the accumulation of organic acids [18], and longer periods of sunshine did not increase the volatile oil composition [19]. This may be related to the fact that A. sinensis is a low temperature, short sunshine plant [20].…”

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“…The appropriate soil pH of A. sinensis is 6.5-8. Investigation found that the soil in the Gansu production area was alkaline; thus, the content of the index components negatively correlated with the soil pH [22].…”