To examine polyamines (PAs) effect in modulating the drought induced by polyethylene glycol (PEG) in maize (Zea mays L.) seedlings (variety Khoibhutta, 8 day seedlings grown in petri dish in incubator) were subjected to 20% PEG (polyethylene glycol) followed by 20 µmol PAs, Putrescine (Put), Spermidine (Spd) and Spermine (Spm) with PEG solution for 48 hours. Sharp decrease in Relative Water Content (RWC), Chl a, Chl b, carotenoid (Car) and total pigment content was observed under drought compared to control condition, while PAs application reversed their decreasing trends. PEG significantly increased Reactive Oxidative Species (ROS) [superoxide (O2•−) and H2O2], Methyl Glyoxal (MG), Melondialdehyde (MDA) and Lipoxigenase (LOX) activity, while Pas decreased the contents considerably (except MG) as compared to those under drought. Drought increased proline content, which was further augmented in PA treatments. PAs failed to incline glyoxalase’s (Gly-I and Gly-II) activities, reduced under PEG. The activity and western blot confirmed the accumulation of Glutathione S-Transferase (GST) under drought, but PAs failed to augment the activity. Ascorbic Acid (AsA) and Glutathione (GSH) got oxidized into Dehydroascorbate (DHA) and oxidized Glutathione (GSSG) under drought but PAs effectively maintained homeostasis. Superoxide Dismutase (SOD), Peroxidase (POD), Ascorbate Peroxidase (APX), Glutathione Peroxidase (GPX), Monodehydroascorbatereductase (MDHAR), Dehydroascorbatereductase (DHAR), and Glutathione Reductase (GR) inclined in drought stressed seedlings, while Catalase (CAT) activity decreased under drought. PAs addition increased SOD, POD, GPX, CAT, MDHAR, and GR activities, but declined DHAR activity. These findings suggested important role of PAs in increasing tolerance under short term drought by modulating antioxidant effect.

Poor seed germination obstructs the early and uniform seedling emergence at the sub-optimal conditions which can be a major setback to early spring cucumber growers. Different seed priming methods ought to be efficient solutions for the problem. To standardize the best priming method, an experiment was laid out in a Completely randomized design at the Horticulture lab of IAAS, Lamjung Campus. The treatment consisted of demineralized distilled water (hydropriming), hormonal priming (GA3 100ppm and GA3 200 ppm), halopriming (NaCl 0.5% and KNO3 0.5%), and non-primed seeds as control. The seeds were soaked in the respective treatment for 24 hours and then dried to initial moisture content under shade conditions. Observation recorded significantly highest germination percentage in GA3 100ppm (19.25%) and hydro priming (19.25%). The lowest mean germination time was found in GA3 100ppm (4.19days) which was significantly at par with GA3 200ppm (4.33days) and hydro priming (4.48days). The germination energy was found highest in GA3 100ppm (39.58) followed by GA3 200ppm (33.65) and dry weight was recorded highest in hydropriming (0.0252g) followed by GA3 100ppm (0.0250g) whereas the highest root length was observed in KNO3 priming (12.955cm) which is statistically at par with hydropriming (11.42cm), GA3 200 ppm (10.872cm) and NaCl priming (10.42cm). The plumule length was observed highest in KNO3 (13.00cm) followed by NaCl (11.25cm). All primed seeds showed increased seedling vigor compared to the unprimed seeds. The study showed that applied treatment notably increased the germination characteristics and seedling stand.

The aim of this study was to investigate the effects of exogenous Melatonin (100, 300 and 500 µM) and L-tryptophan (125, 250, 375 ppm) applications on some growth parameters of lettuce plants grown under salt stress. The study was carried out under semi-controlled greenhouse conditions in spring (March/April) season. The exogenous applications to lettuce plants were carried out two times as foliar spraying. Salt stress was generated by adding NaCl (0 mM, 100 mM, 200 mM) to irrigation water. The complete randomized design was used with three replications in this experiment. At the end of the study, it was found that the highest doses of exogenous applications had the highest effect on the parameters of the number of leaves, salinity necrosis, fresh leaf weight, fresh root weight, and total surface area of lettuce plants under 200 mM salinity condition. When the effects of the subtract on these values were compared, the effect of melatonin was found to be more pronounced. Leaf width, leaf length, and leaf surface temperature values were not affected by the external application. These values only changed depending on salt concentration. As a result of the study, it was concluded that the application of 500 µM melatonin significantly increased salt tolerance in lettuce plants. However, in order to reach a more general conclusion, the dose ranges and genotype/variety numbers should be increased.

The most significant crop losses worldwide occur due to unfavorable temperatures such as heat, drought, cold, and freezing. Minerals like silicon can play important roles in the growth, development, and stress responses of plants. In this study, changes in stem/root length, dry weight, relative water content and silicon content, of peas under cold and freezing stress, as well as antioxidant system indicators such as proline, malondialdehyde, hydrogen peroxide, and chlorophyll levels, ion leakage, and the expressions of genes coding for the topoisomerase TOP2 and DNA helicase PDH47 enzymes, which play important roles in the replication, transcription, and repair of DNA molecules, were examined in root and stem tissues in the presence of two different concentrations of silicon. The results of the study showed that silicon application under cold and freezing stresses has induced various changes in pea metabolism, including increases in cell membrane integrity parameters and superoxide dismutase enzyme activity, as well as increase in the expressions of TOP2 and PDH47 genes. These changes have been found to have positive effects on the pea cold and freezing tolerance.