Glycine Betaine and Salicylic Acid Induced Modification in Water Relations and Productivity of Drought Wheat Plants

A study of parameters associated with adjustments in internal water balance, namely: diurnal variation in transpiration rate, stomatal opening area, relative water content, water use efficiency, hormonal level of wheat flag leaves in relation to grain yield is presented. Drought induced marked decreases in diurnal and mean daily values of transpiration rate, stomatal pore areas (on upper and lower sides), relative water content, water use efficiency, indole-3-acetic acid (IAA), gibberellic acid (GA3), cytokinins (CKs) and grain yield but led to a significant increase in the abscisic acid (ABA) concentration in flag leaves of the wheat cultivars. Grain presoaking in salicylic acid or foliar application with glycine betaine alleviated the stress by keeping water within leaves and consequently recover the turgidity of stressed plants by restricting the transpiration rate, stomatal closure, decreasing the ABA level and enhancing the growth promoters particularly (IAA, GA3 & CKs) particularly with the sensitive cultivar. Furthermore, the effect was more pronounced with glycine betaine + salicylic acid treatment. The grain yield appeared to be positively correlated with IAA, GA3, CK, RWC, WUEG and WUEB but negatively correlated with ABA, SWD, transpiration rate and stomatal areas on both wheat cultivars

Does Glycine Betaine and Salicylic Acid Ameliorate the Negative Effect of Drought on Wheat by Regulating Osmotic Adjustment through Solutes Accumulation?

A pot experiment was conducted to evaluate the beneficial effect of foliar application of glycine betaine (10mM), grain presoaking in salicylic acid (0.05 M) and their interaction on drought tolerance of two wheat (Triticum aestivum L.) cultivars (sensitive, Sakha 94 and resistant, Sakha 93). Osmotic pressure, some osmolytes concentration and grain yield were determined. Water stress caused an increase in osmotic pressure, proline, total soluble nitrogen, total soluble sugars, organic acids, ions (Na+, K+, Ca+2, Mg+2 and Cl-) content as well as Na+/K+ ratio in cell sap flag leaves of both wheat cultivars. The resistant variety had higher values of osmotic pressure, proline, organic acids and ions content than the sensitive one. On the other hand, water stress induced marked decrease (P<0.05) in grain yield. The applied chemicals mitigated the effect of water stress on the used wheat cultivars. The effect was more pronounced with glycine betaine + salicylic acid treatment. The applied chemicals increased the osmotic pressure, the osmolytes concentrations as well as the grain yield. Furthermore, the osmotic pressure of flag leaf sap appeared to depend on proline, TSN, TSS, organic acids and the ions content. The economic yield (grain yield) was positively correlated with proline, keto-acids and osmotic pressure but negatively correlated with TSN, TSS and citric acid

Glycine betaine and salicylic acid induced modification in productivity of two different cultivars of wheat grown under water stress

A pot experiment was conducted to evaluate the beneficial effect of foliar application of glycine betaine (10mM), grain presoaking in salicylic acid (0.05 M) and their interaction on drought tolerance of two wheat (Triticum aestivum L.) cultivars (sensitive, Sakha 94 and resistant, Sakha 93). Water stress decreased wheat yield components (spike length, number of spikelets / main spike, 100 kernel weight, grain number / spike, grain yield / spike, grain yield / plant, straw yield / plant, crop yield / plant, harvest, mobilization and crop indices) and the biochemical aspects of grains(grain biomass, carbohydrates, total protein, total phosphorus, ions content and amino acids) in both wheat cultivars. The applied chemicals appeared to alleviate the negative effects of water stress on wheat productivity (particularly the sensitive one) and the biochemical aspects of yielded grains. The effect was more pronounced with GB+SA treatment. This improvement would result from the repairing effect of the provided chemicals on growth and metabolism of wheat plants grown under water deficit condition. In response to the applied water stress and the used chemicals, the grain yield of the sensitive and resistant wheat cultivars was strongly correlated with all the estimated yield components (shoot length, spike length, plant height, main spike weight, number of spikelets per main spike, 100 kernel weight, grain number per spike, grain weight per plant, straw weight per plant, crop yield per plant, harvest, mobilization and crop indices)

Does Exogenous Application of Kinetin and Spermine Mitigate the Effect of Seawater on Yield Attributes and Biochemical Aspects of Grains?

A pot experiment was conducted to evaluate the effect of grain presoaking in kinetin ( 0.1 mM), spermine (0.3 mM) and their interaction on yield components and biochemical aspects of yielded grains of wheat plants irrigated with 25% seawater . Seawater induced marked reduction in biochemical aspects of yielded grains especially carbohydrates content, nitrogenous constituents, total protein and nucleic acids contents as well as proline and organic acids (citric and keto-acids) content. Conversely, seawater stress increased phosphorus and ions (Na+, K+ and Cl-) content. Application of kinetin or spermine appeared to mitigate the effect of seawater stress on wheat yield and the biochemical aspects of yielded grains. The effect was more pronounced with kinetin + spermine treatment

Wheat can acclimate to seawater by pretreatment with kinetin and spermine through osmotic adjustment and solutes allocation

A key issue in salt adaptation is the osmotic adjustment, therefore, during ear emergence the effect of exogenous application of kinetin and spermine on osmotic pressure (OP) and solutes allocation (total soluble sugars, total soluble nitrogen, proline, organic acids and inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl-) were quantified in flag leaf of wheat plants irrigated by seawater at 25%. Seawater salinity induced significant increase in osmotic pressure. Furthermore, seawater stress induced marked increase in total soluble sugars, total soluble nitrogen, proline, organic acids, as well as Na+, K+, Ca++, Mg++, Cl- and P+++ in wheat flag leaf. On the other hand, seawater decreased SPR, SAR and PAR in flag leaves of wheat plants. Grain priming with kinetin, spermine or their interaction appeared to mitigate the ill effect of seawater on wheat plants by increasing its own capability to be more tolerant against seawater salinity by inducing additional increase in osmotic pressure and the osmolytes concentrations in flag leaf during ear emergence. Moreover, the effect was more pronounced with the interaction of kinetin and spermine treatment

Comparative Morpho-Biochemical Responses of Wheat Cultivars Sensitive and Tolerant to Water Stress

Water stress is likely the most important factor that adversely affects plant growth and development. In this study two wheat cultivars Gemmieza-7 (sensitive) and Sahel-1 (tolerant) were subjected to water stress and compared in terms of growth parameters (growth vigor of root and shoot), water relations (relative water content and saturation water deficit ) and protein as well as nucleic acids (DNA and RNA) content in flag leaves of both cultivars. In general, water stress caused noticeable reduction in almost all growth criteria of root, shoot and flag leaf which was consistent with the progressive alteration in water relations, protein and nucleic acids content of both cultivars during grain filling. Furthermore, degree of leaf succulence and degree of leaf sclerophylly were severely affected by water stress in both wheat cultivars. In relation to wheat cultivar, the sensitive was more affected by water stress than the tolerant one. Generally, the application of salicylic acid, trehalose or their interaction induced marked increase in growth vigor of root and shoot, water relations and protein as well as nucleic acids in flag leaves of both wheat cultivars in compare with control and water stressed plants. In conclusion, Sahel-1 has suitable mechanisms to enable it to respond more effectively to water stress than Gemmieza-7

Endophytic actinomycetes from spontaneous plants of Algerian Sahara: indole-3-acetic acid production and tomato plants growth promoting activity

Twenty-seven endophytic actinomycete strains were isolated from five spontaneous plants well adapted to the poor sandy soil and arid climatic conditions of the Algerian Sahara. Morphological and chemotaxonomical analysis indicated that twenty-two isolates belonged to the Streptomyces genus and the remaining five were non- Streptomyces. All endophytic strains were screened for their ability to produce indole-3-acetic acid (IAA) in vitro on a chemically defined medium. Eighteen strains were able to produce IAA and the maximum production occurred with the Streptomyces sp. PT2 strain. The IAA produced was further extracted, partially purified and confirmed by thin layer chromatography (TLC) analysis. The 16S rDNA sequence analysis and phylogenetic studies indicated that strain PT2 was closely related to Streptomyces enissocaecilis NRRL B 16365T, Streptomyces rochei NBRC 12908T and Streptomyces plicatus NBRC 13071T, with 99.52 % similarity. The production of IAA was affected by cultural conditions such as temperature, pH, incubation period and L-tryptophan concentration. The highest level of IAA production (127 lg/ml) was obtained by cultivating the Streptomyces sp. PT2 strain in yeast extract-tryptone broth supplemented with 5 mg L-tryptophan/ ml at pH 7 and incubated on a rotary shaker (200 rpm) at 30°C for 5 days. Twenty-four-hour treatment of tomato cv. Marmande seeds with the supernatant culture of Streptomyces sp. PT2 that contained the crude IAA showed the maximum effect in promoting seed germination and root elongation

Impact of osmotic stress on seedling growth observations, membrane characteristics and antioxidant defense system of different wheat genotypes

The objective of the present study was to find out a straightforward technique for screening the tolerance of ten wheat genotypes to two levels of osmotic stress at early seedling stage. Data revealed that polyethylene glycol-induced drought had general negative effect on seedling morphological characters indicated by plumule and radicle length, number of adventitious roots as well as seedling biomass and water content. Water deficit could also suppress membrane integrity by stimulating lipid peroxidation with marked increase in membrane leakage and subsequent decrease in its stability index. For all the addressed germination parameters and seedling membrane features, the impact of severe drought was more pronounced than that of moderate drought. Simultaneously, moderate stress could activate peroxidase, polyphenol oxidase and ascorbic peroxidase of the studied genotypes; but these enzymes were inhibited by severe stress. The activity of catalase, superoxide dismutase and glutathione reductase was conversely retarded by drought whether at moderate or severe level. More interestingly, a novel function “Stress Impact Index; SII” was introduced to rank the estimated morpho-physiological traits (SIItrait) as well as the considered genotypes (SIIgenotype) according to their sensitivity to stress. Values of SIItrait implied that germination parameters were generally affected by drought more intensively than membrane characteristics and finally came the antioxidant enzymes with the least degree of suppression when applying stress. Based on the magnitudes of SIIgenotype, Sids 13 seemed to be the most drought-tolerant wheat cultivar while Shandawel 1 could be the most sensitive one at their juvenile growth stage