Water scarcity and increasing salinity stress are significant challenges in the farming sector as they often exacerbate each other, as limited water availability can concentrate salts in the soil, further hindering plant growth. Lettuce, a crucial leafy vegetable with high nutritional value, is susceptible to water availability and quality. This study investigates the growth and development of lettuce plants under water scarcity and varying levels of salinity stress to identify effective strategies for reducing water consumption while maintaining or improving plant productivity. Field experiments were designed to simulate three drought levels (50, 75, and 100% of class A pan evaporation) and three salinity stress levels (control, 1500, and 3000 ppm NaCl), assessing their impact on lettuce’s morphological and biochemical parameters. The combination of reduced water supply and high salinity significantly hindered growth, underscoring the detrimental effects of simultaneous water deficit and salinity stress on plant development. Non-stressed treatment enhanced nitrogen, phosphorus, and potassium contents and progressively decreased with the reduction in water supply from 100% to 50%. Interestingly, higher salinity levels increased total phenolic, flavonoid, and antioxidant activity, suggesting an adaptive stress response. Moreover, antioxidant activity, evaluated through DPPH and ABTS assays, peaked in plants irrigated with 75% ETo, whether under control or 1500 ppm salinity conditions. The Yield Stability Index was highest at 75% ETo (0.95), indicating robust stability under stress. The results indicated that lettuce could be cultivated with up to 75% of the water requirement without significantly impacting plant development or quality. Furthermore, the investigation demonstrated that lettuce could thrive when irrigated with water of moderate salinity (1500 ppm). These findings highlight the potential for reducing water quantities and saline water in lettuce production, offering practical solutions for sustainable farming in water-scarce regions.

As a biostimulant, amino acids play crucial roles in enhancing plant growth and development. These roles, combined with the ability to be approved for organic usage, make amino acids a good choice for sustainable farming systems. This work investigates the effect of onion seed priming with different exogenous amino acids, specifically the impact of seed priming in enhancing a diverse range of morpho-physiological responses of onion seedlings. Here, we primed onion seeds (Cultivar Giza 6) with ten exogenous amino acids. Based on the growth parameters of onion seedlings, data showed that glutamine significantly improved the most studied parameters. Germination percentage (GP) ranged from 85% in Methionine (Met) to 98.5% in Proline (Pro) and Tryptophan (Try), with 10% over the control treatment. Glutamine (Glu) enhanced the vigor index (VI) of onion, giving the seeds a high ability to produce normal seedlings. The most extended root system (≥3.3 cm) was obtained from Glu, Glycine (Gly), Pro, and Try treatments. The maximum shoot length was obtained from treatments (Glu and Try) with more than 60% over control. Priming onion seeds with amino acids (AAs) increased chlorophyll contents compared with non-primed seeds. Glutamine and Threonine (Thr) had the highest results (122 and 127 μg/g fresh weight, respectively), while the Glu treatment registered the highest Carotene contents with 50% over the control treatment. Furthermore, the data illustrate that the principal component analysis-1 (PCA1) indicates 67.2% variability, and PCA2 indicates 14.8% variability. Strong positive correlations were observed between germination percentage, root length, shoot length, dry matter, chlorophyll a, and carotene. The study concluded that the primed onion seeds by glutamine, proline, and tryptophan had the best germination rates.

Studying the biostimulation effect of amino acids indicated their possible role in salt stress mitigation. In this investigation, six exogenous amino acids (alanine (Ala), arginine (Arg), glutamine (Glu), glycine (Gly), methionine (Met), and proline (Pro)) at 0.5 g/L were sprayed to evaluate their impact on lettuce plants cultivated under simulated salt stress conditions. Photosynthetic pigments, ion absorption, endogenous amino acids contents, catalase (CAT), and peroxidase (POD) enzyme activities were determined. A significant alleviation of salt stress was noticed when EAAs were used in the stress-induced plants, and applying Gly, Met, and Pro improved the plant status under salt stress conditions. The highest electric conductivity (568 μS/g) was testified from the control treatment (50 mM NaCl), while applying exogenous amino acids reduced electrical conductivity (EC), and the result was located between 469 and 558 μS/g. AAs alleviated Cl^- anions in the lettuce leaves by 25% in comparison to control plants. Na⁺ cations were alleviated when the stress-induced plants were sprayed with amino acids. In contrast, applying amino acids promoted K⁺ uptake, and Arg presented the highest contents (3226 μg/g). AAs promoted chlorophyll (chl a and chl b) concentrations compared to the control treatment, and Met produced the maximum chl a content, while the carotene (car) contents significantly augmented when Gly, Met, and Pro were applied. AAs were highly generated in non-stressed treatment (Std) compared to the control. Under simulated salinity stress, Met and Pro application enhanced proteinogenic amino acids expression. Compared to Ctl treatment, peroxidase enzyme activities significantly diminished in the other treatments, which fell by over 40% when Gly, Met, and Pro were sprayed.

Lettuce plants (Lactuca sativa L.) were grown under salinity stress conditions. Amino acids (histidine (His), lysine (Lys), phenylalanine (Phe), and threonine (Thr)) were individually applied to the seedlings to study their impact on the status of the photosynthetic pigments, ion absorption, proteinogenic metabolism, and peroxidase activity. Investigating the effect of exogenous amino acids on the metabolism processes showed their potential role in inducing salt stress tolerance in lettuce plants. Generally, a destructive impact on lettuce plant morphology was observed when the plants were exposed to salt stress. In contrast, the significant (p < 0.05) mitigation of salt stress was registered when EAAs were applied to the stressed seedlings while using Threonine and lysine enhanced the status of the plants under salinity stress. For the salt treatment, the maximum electric conductivity (580.2 μS/g) was reported while applying EAAs to stressed plants’ decreased EC, and the data ranged from 522 to 554 μS/g. EAAs decreased the chloride ions in the leaves by 23–30% compared to in the stressed plants. Additionally, the sodium contents were mitigated when the stressed plants were sprayed with EAAs. In contrast, applying EAAs enhanced the potassium uptake, and Thr gave the highest K⁺ contents (3022 μg/g). EAAs increased the chlorophyll content compared to the control except when histidine was applied, while the carotene contents significantly increased when histidine and phenylalanine were used. Endogenous amino acids are highly expressed in non-stressed lettuce plants compared to the stressed ones. Under salt stress conditions, the threonine usage increased the expression of proteinogenic amino acids except methionine and tyrosine. Compared to the salt-stressed plants, the peroxidase activity significantly decreased in the other treatments, which fell by over 32% when His, Lys, and Phe were applied.

Blossom-end rot (BER) is a physiological disorder caused by calcium deficiency, often paired with moisture stress and irregular traditional watering practices. To understand the biological mechanism affecting the incidence of BER, different tomato genotypes were cultivated in sandy soil and were traditionally irrigated. Nine tomato genotypes were investigated to assess their susceptibility to BER, and the incidence rate varied from 7.1% in “Voskhod” to 57.6% in “Majnat” genotypes. This study also comprehensively analyzed various physiological and biochemical parameters to elucidate their correlation with BER incidence in tomato plants. Our findings revealed a range of parameters positively correlated with BER incidence, including the relative water content of roots, the number of fruits per plant, vitamin C content, and potassium content. Parameters related to fruit quality, such as titratable acidity, peroxidase content, and firmness degree, also showed positive correlations with BER incidence. Conversely, parameters such as total yield per hectare, chlorophyll content, average plant height, and calcium content demonstrated strong negative correlations with BER incidence, suggesting potential protective effects against this disorder. This study highlights that genotypes with higher marketable yields, such as ‘Voskhod’ (65 tons/ha), showed lower BER incidence, underscoring the importance of selecting the appropriate genotype in improving yield and reducing blossom-end rot in tomato fields. Conversely, cultivars with high BER sensitivity, such as ‘Chelnok’ (26.3 tons/ha), require specially designed cultivation management to avoid production declines.

Актуальность. Томат считается важной овощной культурой, которая играет большую роль в сохранении здоровье человека, поэтому исследования морфологических, физиологических и пищевых свойств томата актуальны. Фермеры часто используют некоторые химические вещества, которые имеют сходную структуру и активность с эндогенным растительным гормоном, называемым (экзогенным), в качестве недорогой альтернативы для регулирования роста растений и увеличения урожайности. Влияние многих из этих веществ на рост и качество сельскохозяйственных культур еще не изучено. Методика. Целью данного исследования является оценка влияния четырех регуляторов роста (Крезацин, Хитозан, Циркон и Энерген) на рост, продуктивность и качество двух российских сортов томата (Моряна и Супергол) в условиях дельты Волги. Результаты. Результаты показали, что использование Энерген на сорте Моряна усилило большинство изученных признаков (всхожесть – 83,1%, свежая масса вегетативных частей – 241,9 г, сухая масса вегетативных частей – 74,4 г, количество цветков / растений – 51,0, количество плодов / растений – 35,6, урожайность растений – 2,44 кг, сумма сахаров – 5,1°Brix, содержание аскорбиновой кислоты – 25,6 мг/100 г. Применение Энергена на сорте Супергол дало максимальное значение высоты растений (85,6 см), массы плода (72,6 г); в то время как при использовании Крезацина на сорте Mоряна было достигнуто самое высокое содержание сухого вещества в плодах (6,77%) и кислотность (0,53%). Применение Циркона на сорте Моряна привело к увеличению количества листьев на растении (56,8) и содержания нитратов (27,6 мг/кг). Максимальный LAI (150,1 см2 ) получен при использовании хитозана на сорте Супергол, тогда как его применение на сорте Моряна дало самый высокий уровень каротиноидов (4,12%).