Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality, and energy. It is the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimensional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabolomics, proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotectants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.

Field-based trials and genotype evaluation until yielding stage are two important steps in improving the salt tolerance of crop genotypes and identifying what parameters can be strong candidates for the better understanding of salt tolerance mechanisms in different genotypes. In this study, the salt tolerance of 18 bread wheat genotypes was evaluated under natural saline field conditions and at three saline irrigation levels (5.25, 8.35, and 11.12 dS m⁻¹) extracted from wells. Multidimensional evaluation for salt tolerance of these genotypes was done using a set of agronomic and physio-biochemical attributes. Based on yield index under three salinity levels, the genotypes were classified into four groups ranging from salt-tolerant to salt-sensitive genotypes. The salt-tolerant genotypes exhibited values of total chlorophyll, gas exchange (net photosynthetic rate, transpiration rate, and stomatal conductance), water relation (relative water content and membrane stability index), nonenzymatic osmolytes (soluble sugar, free proline, and ascorbic acid), antioxidant enzyme activities (superoxide dismutase, catalase, and peroxidase), K⁺ content, and K⁺/Na⁺ ratio that were greater than those of salt-sensitive genotypes. Additionally, the salt-tolerant genotypes consistently exhibited good control of Na⁺ and Cl⁻ levels and maintained lower contents of malondialdehyde and electrolyte leakage under high salinity level, compared with the salt-sensitive genotypes. Several physio-biochemical parameters showed highly positive associations with grain yield and its components, whereas negative association was observed in other parameters. Accordingly, these physio-biochemical parameters can be used as individual or complementary screening criteria for evaluating salt tolerance and improvement of bread wheat genotypes under natural saline field conditions.

Water deficit stress can negatively affect oil quality, crop yields and soil infertility. Thus, we investigated the effects of rice-straw biochar, foliar silicon and their combination on quality, yield and physiological traits of sunflower grown under three water deficit stress treatments. Water stress treatments were 50% (WS₀; no stress), 70% (WS₁; moderate stress) and 90% (WS₂; severe stress) depletion of the available soil moisture. The results showed that WS₁ and WS₂ negatively affected oil quality, mycorrhizal spores, yield and physiological traits of the sunflower; however, biochar, silicon and their combination significantly (p ≤ 0.05) improved most of those traits. Oil and oleic acid contents of sunflower grown under WS₂ were decreased by 18% and 25.8% compared to those grown under WS₀, respectively. Nevertheless, the biochar and silicon combination resulted in higher oil (10.2%) and oleic acid (12.2%) in plants grown under WS₂ than those grown in untreated plots. Also, a significant increase (182% and 277%) in mycorrhizal spores was obtained in soil treated combination of biochar and silicon under WS₁ and WS₂ in comparison to untreated soil, respectively. On the other hand, plants grown under WS₁ and WS₂ exhibited reduced seed yield ha⁻¹ by 16.5% and 53.5% compared to those grown under WS_0, respectively. However, seed yield ha⁻¹ were increased by 26.8% and 27.1% in plots treated with combined treatment compared to untreated plants, respectively. In addition, the biochar and silicon combination significantly increased stomatal conductance by 21.4% and 12.1%, reduced proline by 56.6% and 51.2% and reduced catalase activity by 13.4% and 17.3% under WS₁ and WS₂ compared to those grown in untreated plots, respectively. Therefore, the combined treatment of biochar and silicon can minimize and alleviate the negative effects of WS₁ and WS₂, improve oil quality, physiological traits, microbial activity and seed yield ha⁻¹ in sunflower plants.

Improving salt tolerance of genotypes requires a source of genetic variation and multiple accurate selection criteria for discriminating their salt tolerance. A combination of morpho-physiological and biochemical parameters and multivariate analysis was used to detect salt tolerance variation in 15 wheat lines developed by doubled haploid (DHL) technique. They were then compared with the salt-tolerant check cultivar Sakha 93. Salinity stress was investigated at three salinity levels (0, 100, and 200 mM NaCl) for 25 days. Considerable genetic variation was observed for all traits, as was high heritability (>60%) and genetic gain (>20%). Principal component analysis indicated the ability of nine traits (root number, root length, root dry weight, shoot length, shoot dry weight, specific root length, relative water content, membrane stability index, and catalase) to identify differences in salinity tolerance among lines. Three traits (shoot length, shoot dry weight, and catalase) were indicative of salt-tolerance, indicating their importance in improving and evaluating salt tolerant genotypes for breeding programs. The salinity tolerance membership index based on these three traits classified one new line (DHL21) and the check cultivar (Sakha 93) as highly salt-tolerant, DHL25, DHL26, DHL2, DHL11, and DHL5 as tolerant, and DHL23 and DHL12 as intermediate. Discriminant function analysis and MANOVA suggested differences among the five groups of tolerance. Among the donor genotypes, Sakha 93 remained the donor of choice for improving salinity tolerance during the seedling stage. The tolerated lines (DHL21, DHL25, DHL26, DHL2, DHL11, and DHL5) could be also recommended as useful and novel genetic resources for improving salinity tolerance of wheat in breeding programs.

The primary goal of integrated nutrient management (INM) strategies is to substitute a portion of chemical fertilizers with a more sustainable and environmentally safe organic compost in order to mitigate soil degradation, improve crop production, and protect the environment. Therefore, the present study was conducted to assess the impacts of different INM practices, namely full-dose NPK (T1), compost of cow manure at 5 t ha⁻¹ (T2), compost of poultry manure at 5 t ha⁻¹ (T3), compost of mixed sheep and camel manure at 5 t ha⁻¹ (T4), 50% NPK combined with the mixture of the three types of composts at the rate of 5 t ha⁻¹ (T5) or 10 t ha⁻¹ (T6), and mixture of the three types of composts at the rate of 10 t ha⁻¹ (T7), 15 t ha⁻¹ (T8), or 20 t ha⁻¹ (T9) with or without biofertilizers for each treatment on several physiochemical and biological proprieties of soil and final grain yield of field crops after 2 years of field-scale experiments. The results showed that all INM practices generally significantly (p < 0.05) improved the initial values of all tested soil physiochemical and biological proprieties, whereas improvement was more prominent for the plots treated with T5–T9, compared with those treated with T1–T4. Seed inoculation with biofertilizers also significantly (p < 0.05) increased different soil proprieties by 2.8–12.0%, compared to that of the non-inoculation treatment. Principal component analysis revealed that most soil chemical properties were closely associated with T5–T6 treatments, while most soil physical and biological properties appeared to be more related to T7–T9 treatments. Our results indicated that recycling agricultural wastes into new productive composts and integrating it into appropriate INM practices as shown in T5–T9 treatments may induce favorable changes in soil properties and improve crop production under arid conditions even in the short term.

Several species belonging to the genus Tabernaemontana have been well researched and utilized for their wide-ranging biological activities. A few of the most prominent species include Tabernaemontana divaricata, Tabernaemontana catharinensis, Tabernaemontana crassa, and Tabernaemontana elegans. These species and many others within the genus often display pharmacological importance, which is habitually related to their chemical constituents. The secondary metabolites within the genus have demonstrated huge medicinal potential for the treatment of infections, pain, injuries, and various diseases. Regardless of the indispensable reports and properties displayed by Tabernaemontana spp., there remains a wide variety of plants that are yet to be considered or examined. Thus, an additional inclusive study on species within this genus is essential. The current review aimed to extensively analyze, collate, and describe an updated report of the current literature related to the major alkaloidal components and biological activities of species within the genus Tabernaemontana.