Effects of Climate Temperature and Water Stress on Plant Growth and Accumulation of Antioxidant Compounds in Sweet Basil (Ocimum basilicum L.) Leafy Vegetable

Abstract

The effects of climate temperature and water stress on growth and several stress markers were investigated in sweet basil plants. Some growth parameters (shoot length and number of leaves) and photosynthetic chlorophyll contents were determined every two days during plant growth, and foliage leaf material was collected after 15 and 21 days of treatment. Both climate temperature and water stress inhibited sweet basil plant growth; especially, total chlorophyll levels were decreased significantly in response to high-temperature treatments. Under strong stresses, basil plants induced the synthesis and accumulation of glycine betaine (GB) as a secondary osmolyte, although at less content when compared with the proline content under the same stress conditions. Proline concentrations particularly increased in leaves of both basil stressed plants, accomplishing levels high enough to play a crucial role in cellular osmoregulation adjustment. Stress-induced accumulation of these antioxidant compounds was detected in sweet basil. Therefore, it appears that sweet basil-treated plants are able to synthesize antioxidant compounds under strong stress conditions. On the other hand, total sugar concentrations decreased in stress-treated basil plants. Both temperature and water stress treatments caused oxidative stress in the treated plants, as indicated by a significant increment in malondialdehyde (MDA) concentrations. An increase in total phenolic and flavonoid concentrations in response to water stress and a highly significant decrease in carotenoid concentrations in basil leaves were observed; flavonoids also increased under high climate temperature conditions.

Interactive Impacts of Temperature and Elevated CO2 on Basil (Ocimum basilicum L.) Root and Shoot Morphology and Growth

“…While under high-temperature treatment, the index of flavonoids of basil decreased considerably. These findings contradict many studies [31,38,39] because increased flavonoids are usually associated with thermophilic plant defense mechanisms against heat stress. Moreover, increased growth temperature from 30/22 • C to 38/30 • C for basil under elevated CO 2 produced more Anth content.…”

“…In this current research, increasing the temperature to 38/30 • C at ambient CO 2 concentration caused less adverse effects on the early season's morphological features (17 DAT) of basil. Previous research indicated an increase in the PH, NN, and BN primarily because basil plants prefer warmer temperatures [31]. For instance, in this current study, high-temperature stress caused a significant decrease in late-season basil PH, NN, and BN by 17%, 16%, 18%, respectively, compared to the control treatments.…”

Yield, Physiological Performance, and Phytochemistry of Basil (Ocimum basilicum L.) under Temperature Stress and Elevated CO2 Concentrations

“…Moreover, basil leaves subjected to low-temperature stress were identified to experience chlorosis due to rapid degradation of carotenoid, chlorophyll, and antioxidant content [11,18]. It is important to note that the alteration of basil leaf pigments due to chilling stress could damage the photosynthetic apparatus, with detrimental impacts on plant growth and development.…”

The Short-Term Metabolic Modulation of Basil (Ocimum basilicum L. cv. ‘Genovese’) after Exposure to Cold or Heat

“…In addition, an increased chlorophyll a / b ratio and decrease in chlorophyll to carotenoid ratio can be seen in heat-tolerant cultivar [ 5 , 22 ]. Al-Huqail et al [ 14 ] showed total chlorophyll reduction in basil leaves under high temperature; however, the authors did not indicate a specific genotype used in this study. In our study, both short-term chilling and heat stress caused a significant increase in chlorophyll a , chlorophyll b , and carotenoid content in leaves of tested basil cultivar.…”

“…It is known that, because of a poor tolerance of young leaves and buds to low temperature in cultivated plants, a sudden frost in early spring causes cold stress and negatively affect the commercial yield, whereas the combination of warmer maximum temperatures leads to earlier budburst and greater risk of damage [ 8 ]. Therefore, in order to develop improved crops with complete yield potential, it is important to understand the numerous plant mechanisms and their interactions during abiotic stresses and to explore the ways to improve the temperature tolerance of basil plants [ 14 ].…”