Abstract
To assess the effect of triacontanol (TRIA) on rice plants grown under normal or drought conditions, rice seeds were presoaked in TRIA (35 ppm) for two hours. After 20 days of sowing, rice seedlings developed from TRIA-treated or untreated seeds were subjected to drought stress. After 10 days of plant exposure to drought stress, data of major growth attributes and the content of photosynthetic pigments were recorded. Moreover, the effect of drought stress on stomatal conductance and the photochemical efficiency of PSII (Fv/Fm) were followed. The data obtained indicated that the species of rice (Oryza sativa L.) cultivar Giza 177 under investigation was sensitive to drought stress where there were significant decreases in the fresh and dry weights of shoots and roots and in stomatal conductance, as well as in the content of chlorophyll a, chlorophyll b, and carotenoids. Seed priming with TRIA enhanced both growth and acquired plant tolerance to drought stress. Thus, TRIA via the enhancement of stomatal conductance through the regulation of stomatal closure, the rate of water loss, ABA metabolism, the accumulation of osmolytes, and the regulation of aquaporins genes improved the water status of plants grown under water scarcity. Moreover, TRIA via increasing the content of free amino acids and sugars under drought stress may increase the chance of plant tissues to retain more water under scarcity conditions.
Highlights
Drought is one of the major environmental constrictions limiting plant development and productivity [1]
The results obtained showed that the relative water content was decreased in the leaves of rice seedlings exposed to drought
TRIA pretreatment induced a significant increase in Chl a, Chl b, and the contents of leaves of drought-stressed seedlings, compared with the untreated stressed controls (Table 3)
Summary
Drought is one of the major environmental constrictions limiting plant development and productivity [1]. The major crops will exhibit over 65% reduction in their yield by 2050 because of drought all over the world [2,3]. Rice is one of the major staple food crops for most of world population, and belongs to semi-aquatic plants, so it requires a high soil moisture level [4]. Rice plants are susceptible to water scarcity, which induces a variety of morphological, molecular, and physiological changes [5]. It was reported that major growth attributes of important crops are severely affected by drought stress [6]. It was reported that drought stress disturbs the leaf water potential, transpiration rate, and stomatal conductance [7]
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