ALLEVIATION OF DROUGHT STRESS EFFECTS AT DIFFERENT GROWTH STAGES OF WHEAT PLANTS BY FOLIAR SPRAY OF SALICYLIC ACID

Drought stress has adverse effects on crop growth and yield, and its identification and monitoring play vital roles in precision crop water management. Accurately evaluating the effect of drought stress on crop photosynthetic capacity can provide a basis for decisions related to crop drought stress identification and monitoring as well as drought stress resistance and avoidance. In this study, the effects of different degrees of persistent drought in different growth stages (3rd leaf stage, 7th leaf stage and jointing stage) on the maximum carboxylation rate at a reference temperature of 25 °C (Vcmax25) of the first fully expanded leaf and its relationship to the leaf water content (LWC) were studied in a field experiment from 2013 to 2015. The results indicated that the LWC decreased continuously as drought stress continued and that the LWC decreased faster in the treatment with more irrigation. Vcmax25 showed a decreasing trend as the drought progressed but had no clear relationship to the growth stage in which the persistent drought occurred. Vcmax25 showed a significantly parabolic relationship (R2 = 0.701, p < 0.001) with the LWC, but the different degrees of persistent drought stress occurring in different growth stages had no distinct effect on the LWC values when Vcmax25 reached its maximum value or zero. The findings of this study also suggested that the LWC was 82.5 ± 0.5% when Vcmax25 reached its maximum value (42.6 ± 3.6 μmol m−2 s−1) and 67.6 ± 1.2% (extreme drought) when Vcmax25 reached zero. These findings will help to improve crop drought management and will be an important reference for crop drought identification, classification and monitoring as well as for the development of drought monitoring and early warning systems for other crops or maize varieties.

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Effects on Plant Hormone levels at Different Growth Stages in Diverse Grape Organs with Root Restriction

10.21203/rs.3.rs-681245/v1 ◽

2021 ◽

Author(s):

Jiajia Li ◽

Dongmei Li ◽

Boyang Liu ◽

Ruiqi Wang ◽

Yixuan Yan ◽

...

Keyword(s):

Salicylic Acid ◽

Abscisic Acid ◽

Plant Hormones ◽

Growth Stages ◽

Indolebutyric Acid ◽

Hormone Levels ◽

Berry Quality ◽

Isopentenyl Adenine ◽

Root Restriction ◽

Different Growth Stages

Abstract Endogenous plant hormones play important roles in germination, blossom, senescence, abscission of plants by a series of signal transduction and molecular regulation. The purpose of this research was to investigate the influence of root restriction (RR) cultivation on plant hormones variation tendency at different growth stages in diverse organs or tissues, ‘Muscat Hamburg’ (Vitis ‘Muscat of Alexandria’ × Vitis ‘Trollinger’) grapevine was used as test material. High Performance Liquid Chromatography (HPLC) was used to quantify hormone levels, aiming to investigate the influence of root restriction on the formation and transportation of plant hormones. The results revealed that RR treatment increased abscisic acid, salicylic acid, zeatin riboside, N6-(delta 2-isopentenyl)-adenine nucleoside concentrations, while reduced auxin, 3-indolepropionic acid, 3-indolebutyric acid, gibberellin A3, zeatin, N6-(delta 2-Isopentenyl)-adenine, kinetin, jasmonic acid and methyl jasmonate concentrations. To sum up, our results suggested that RR treatment could initiate stress responses via up-regulating abscisic acid and salicylic acid contents while down-regulating auxin and kinetin contents, resulting in the changes of fruit appearance and improvement of berry quality.

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Methionine-induced regulation of growth, secondary metabolites and oxidative defense system in sunflower (Helianthus annuus L.) plants subjected to water deficit stress

PLoS ONE ◽

10.1371/journal.pone.0259585 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0259585

Author(s):

Gull Mehak ◽

Nudrat Aisha Akram ◽

Muhammad Ashraf ◽

Prashant Kaushik ◽

Mohamed A. El-Sheikh ◽

...

Keyword(s):

Drought Stress ◽

Helianthus Annuus ◽

Water Deficit ◽

Soluble Sugars ◽

Foliar Spray ◽

Shoot Length ◽

Stress Conditions ◽

Growth And Yield ◽

Water Deficit Stress ◽

Growth Stages

Optimum water availability at different growth stages is one the major prerequisites of best growth and yield production of plants. Exogenous application of plant growth regulators considered effective for normal functioning of plants under water-deficit conditions. A study was conducted to examine the influence of exogenously applied L-methionine on sunflower (Helianthus annuus L.) plants grown under water-deficit conditions. Twenty-five-day old seedlings of four sunflower cultivars, FH331, FH572, FH652 and FH623 were exposed to control (100% F.C.) and drought stress (60% F.C.) conditions. After 30-day of drought stress, L-methionine (Met; 20 mg/L) was applied as a foliar spray to control and drought stressed plants. Water deficit stress significantly reduced shoot fresh and dry weights shoot and root lengths, and chlorophyll a content in all four cultivars. While a significant increase was observed due to water deficiency in relative membrane permeability (RMP), malondialdehyde (MDA), total soluble proteins (TSP), total soluble sugars (TSS), ascorbic acid (AsA) and activity of peroxidase (POD). Although, exogenously applied Met was effective in decreasing RMP, MDA and H2O2 contents, it increased the shoot fresh weight, shoot length, chlorophyll a, chlorophyll a/b ratio, proline contents and the activities of SOD, POD and CAT enzymes in all four cultivars under water deficit stress. No change in AsA and total phenolics was observed due to foliar-applied Met under water stress conditions. Of all sunflower cultivars, cv. FH-572 was the highest and cv. FH-652 the lowest of all four cultivars in shoot fresh and dry weights as well as shoot length under drought stress conditions. Overall, foliar applied L-methionine was effective in improving the drought stress tolerance of sunflower plants that was found to be positively associated with Met induced improved growth attributes and reduced RMP, MDA and H2O2 contents under water deficit conditions.

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