Improving the physiological status expressed in adjusting the osmolytes and nutrients balance of plant cell is a crucial matter for ameliorating the hazards of salinity. In this context, humic substances have a significant role for stimulating the plant tolerance to various stresses. Therefore, the current study aimed to assess the importance of foliar spray of humic acid (0 and 150 mg L⁻¹) for avoiding the effect of salt stress (0, 4000 and 8000 mg L⁻¹) on vegetative growth of pittosporum plant, protein, proline, peroxidase activity and nutrient components related to salinity. The treatments were arranged in a randomized complete block design with 3 replicates. Results revealed that the highest vegetative growth was recorded with mg L⁻¹ humic acid. While, salinity levels of 4000, and 8000 mg L⁻¹ led to increases in protein, proline peroxidase activity, and chloride and sodium inions. Compared to humic acid-untreated plants, application of humic acid under salinity level of 4000 mg L⁻¹ enhanced plant height, root fresh weight plant⁻¹, root dry weight plant⁻¹, shoot fresh weight plant⁻¹ and shoot dry weight plant⁻¹ by 12.6, 10.9, 17.7, 43.4, 19.4%, respectively, in the second season. Humic acid application under all salinity levels showed favorable effect for keeping leaves in both seasons, since fallen leaves number was reduced. The increases in potassium (K) content reached about 12.0 and 22.4% under 4000 mg L⁻¹ and 8000 mg L⁻¹, respectively, owing to humic acid application. Protein, proline content and peroxidase activity showed the minimal values under humic acid × salinity level of 4000 mg L⁻¹. It could be concluded that application of humic mitigates the harmful effect of salinity and improves the vegetative growth parameters and physiological status of pittosporum plants while increases the uptake of beneficial nutrients.

Gerbera (Gerbera jamesonii) cv. Jaguar Yellow is an ornamental plant of the Asteraceae family. Ordinarily, farmers use expensive materials such as peat moss as a media substrate in gerbera production, in addition to application high nitrogen fertilizers. Therefore, the current study was designed to assess the yield and quality changes of gerbera flowers owing to utilizing environment-friendly inputs under unheated plastic greenhouse conditions for two seasons of 2017/18 and 2018/19. The experiments were laid out in a randomized complete block design with 3 replicates, each replicate involved 5 pots per treatment. For preparing the soil substrate mixtures, four substances were used which involved peat moss (P), sand (S), vermicompost (V), and compost (C). P + S, P + S + V and P + S + C were assembled whether with or without Azotobacter+Azospirillum as bio stimulant (Bio) addition to obtain six combinations. Results showed that P + S + V + Bio was the effective practice for enhancing gerbera plant height, leaf width, root weight plant plant-1 and leaves weight plant-1. Also, P + S + V + Bio produced the maximum values of leaf chlorophyll, nitrogen, phosphorus, and potassium contents. The differences in flowering initiation between P + S and each of P + S + V, P + S + V + Bio, P + S + C and P + S + C + Bio were not significant. P + S + V + Bio (for flowering duration and flower yield), in addition to P + S + V (for flowering duration) recorded the highest values in both seasons.

Salinization, as a serious climate change phenomenon, continues to cause critical issues for soils and crops. Abundance of genetic diversity of plants could contribute in solving the impacts of salinity. However, the relations between physiological and molecular traits of plant species need deep investigation and interpretation. Pot experiments were conducted in the greenhouse to investigate the difference in behavior between two amaranth species when they were beforehand subjected to salinity-stress conditions, specifically on some specific physiological and molecular characteristics. After 45 days from transplanting, salt stress was induced using a 150 mM sodium chloride solution. Treatments were arranged in randomized complete block design using three replications. After 0, 2, 6, 10, and 24 h, samples were collected to evaluate physiological data as well as diversity of gene expression. The samples were immediately frozen in liquid nitrogen and stored in -80⁰ C ultralow temperature refrigerators. Findings revealed that the red amaranth species (Amaranthus cruentus) was more tolerant to saline stress than the green amaranth species (Amaranthus hypochondriacus). Result data revealed that malondialdehyde (MDA) content in the red amaranth increased after 2 h then decreased (after 6 and 10 h) before rising again after 24 h. In the green amaranth, MDA content initially decreased after 2 h before increasing and later decreasing in a zigzag pattern ending in an increase after 24 h. There was an initial steep rise in proline content of green amaranth after 2 h which continued to still rise moderately till 24 h. In the red amaranth the initial rise in proline continued after 2, 6 and 10 h before it stopped. Results also showed that red amaranth gave higher value of superoxide dismutase (SOD) activity as compared with green amaranth in all tested salinity exposure times. The investigation on the expression of four genes assessed through quantitative PCR indicated the efficiency of red amaranth in increasing the expression of SOS1, HKT1, NHX1, and DGR2 genes, which encode adaptation-related proteins under salinity stress. In summary, the current work demonstrated that red amaranth could be an efficient genetic resource in improving salt-tolerant genotypes belonging to Amaranthus genus.

Purpose: Medicinal plants show a relevant importance in human life and health. The use of natural substances in crop management is not only significant for the plant healthy growth and yield, but also for obtaining safe products. The study aimed to examine the effect of seaweed extract (SW) as a natural source of nutrition and salicylic acid (SA) on plant health, physiology and essential oil profile of French marigold (Tagetes patula L.). Methods: Three levels of salicylic acid, SA50, SA100 and SA200, (50, 100, and 200 mg L^− 1) and three levels of seaweed extract, SW2, SW4 and SW6 (2.0, 4.0, and 6.0 ml L^− 1), in comparison with control treatment (tap water) were applied as foliar sprayings. The seven treatments were arranged in randomized complete block design and were replicated thrice in two growing seasons (2020 and 2021). Results: Findings pointed out that SA200 increased plant height, branches number plant^− 1, stem diameter, leaf area, leaves number plant^− 1, plant fresh weight, and plant dry weight by 32.9, 112.2, 59.2, 34.4, 44.3, 33.0 and 56.9% (averages of the two seasons), respectively, compared to the control treatment (tap water). SW6 increased carotenoids content by 34.8 and 46.4% in 2020 and 2021 seasons, respectively. Salicylic acid at the rate of 200 mg L^− 1 along seaweed extract at 6 ml L^− 1 gave the highest values of total sugars and free amino acids. SA200 alone recorded the maximal value of peroxidase activity surpassing the other treatments. SW6 possessed the greatest essential oil content in both seasons, statistically equaling SA200 in the first season. Huge variations in essential oil profile were recorded under the tested trial treatments. Conclusion: It could be concluded that salicylic acid and seaweed extract foliar application unveiled their involvement in diverse physiological and developmental responses; pigment formation, enzyme activities, flower induction, nutrient uptake, essential oil metabolism, and overall plant growth and development. It is recommended to use the highest concentrations of the tested substances (SA at 200 mg L^− 1 or SW at 6.0 ml L^− 1) for achieving distinctive improvements in physiological responses of French marigold plant.