Drought stress is alarmingly on the rise over the past decades. The growth regulators including salicylic acid (SA) and chitosan are being successfully used to protect plants against biotic and abiotic stresses. To investigate the effect of SA, chitosan and their combination on biochemical traits and cucurbitacin contents in Citrullus colocynthis (L.) under different levels of drought stress, four irrigation levels (control (100% Field capacity: FC), 75, 50 and 25% FC) along with three different treatments by administration of SA and chitosan (150 mg L-1), and their combinations were used. Drought stress significantly increased the amount of sugar, proline, lipid peroxidation and the activity of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) while decreased growth parameters, protein, leaf relative water content (RWC), chlorophyll and carotenoid contents. Although SA could increase some biochemical traits including sugar, chlorophyll and carotenoid contents only in severe level of drought stress, chitosan and the combined treatment exerted beneficial effects in almost all levels of irrigation. Furthermore, combination of SA and chitosan induced more protective effects compared to only chitosan treatment in increasing proline and the activities of SOD and CAT. Combined treatment was also effective in increasing cucurbitacin B, C and L contents but not cucurbitacin E. Combination of SA and chitosan showed the major impact on improving physiological parameters and cucurbitacin contents of C. colocynthis and therefore could be a potential candidate to protect the plant against adverse effects of drought stress. پرونده مقاله

Flixweed is an annual or biennial herbaceous plant. The seeds of this plant are small, slightly elongated, and typically come in two colors that form inside the pod. A lack of synchronized care for the sorrel pods on the main stem leads to grain loss and a reduction in economic yield. The flowering process and the genes involved play a crucial role in coordinating the formation, growth, and maturation of Flixweed pods. The aim of this study was to investigate the expression patterns of genes involved in the flowering process of Flixweed—namely, LFY, TFL, AG, FLC, AP1, and MYB24—under different concentrations of gibberellin and auxin treatments. Thus, increasing or decreasing the expression of these genes can impact the rate of Flixweed grain loss. The results of the analysis of variance showed that the effects of auxin and gibberellin foliar application levels on the relative expression of the LFY, TFL, AG, FLC, AP1, and MYB24 genes were significant at the 1% probability level. Based on a comparison of the results, the mean relative expression levels of the LFY, TFL, AG, and MYB24 genes were influenced by treatments with gibberellic acid and auxin. The highest relative expression of FLC was observed with the application of 60 mg/L auxin. The lowest relative expression levels of LFY (2.9466), TFL (5.6466), AG (4.3066), and MYB24 (-1.6867) were observed with the application of 30 mg/L auxin. The lowest relative expression of FLC and AP1 genes was achieved with the foliar application of 15 mg/L auxin and 60 mg/L gibberellin, respectively. پرونده مقاله