Grafting is used in vegetable production to improve plant vigour and tolerance to soil-borne diseases, yet the biological properties of the graft union remain poorly understood. Here, we investigated culturable bacteria associated with tomato (Solanum lycopersicum L.) graft unions. Bacterial populations reached 105-107 colony-forming units per gram of fresh weight (CFU g-1 FW) in graft union tissues. However, no culturable bacteria were detected from non-grafted stem samples collected from the graft union equivalent position at the corresponding sampling time (i.e. 8 days after grafting in grafted plants). The predominant bacterial genera isolated from graft unions were Microbacterium and Sphingomonas. All isolates tested negative for the hypersensitive reaction in tobacco, indicating their non-pathogenic nature. The isolates exhibited functional traits, including effects on seedling growth, phosphate solubilisation, production or degradation of N-acyl-homoserine lactones, and antibacterial activity against Ralstonia pseudosolanacearum. In addition, isolates were associated with reduced symptom development of bacterial wilt in tomato seedlings under controlled conditions. These results suggest that graft unions may provide a biologically active environment associated with the recovery of diverse culturable bacterial communities. Our findings provide insight into bacteria associated with tomato graft unions and their potential functional properties relevant to horticultural production.
The ripe pulp of the hybrid jackfruit (Artocarpus heterophyllus Lam) cultivar 'Thong Ploy' is dominated by branched-chain esters (92.73% of total esters). Six key volatile organic compounds (VOCs), with high odour activity values (OAVs > 50), five esters and one alcohol, contribute to its sweet aroma, resembling apple and banana, with subtle fermented notes. Methyl 3-methylbutanoate was present throughout maturation, whereas other esters appeared only at the ripe stages. At 25 degrees C, fruit treated with 500 nL L-1 1-methylcyclopropene (1-MCP) ripened on day 12, whereas untreated fruit reached full ripeness by day 8. Under 13 degrees C storage, untreated fruit ripened by day 15, whereas 500 or 1,000 nL L-1 1-MCP-fumigated fruit began ripening on day 20. The use of 1-MCP significantly suppressed volatile production. On day 8 at 25 degrees C, treated fruit produced only 4.66% of VOCs found in controls. Respiration and ethylene were reduced, with untreated fruit peaking at 203.82 mg CO2 kg(-1) h(-1) and 2.55 & micro;L C2H4 kg(-1) h(-1). A 500-nL L-1 dose effectively reduced respiration and ethylene production, thereby delaying ripening. It preserved pulp firmness, colour, soluble solids accumulation, and inhibited ester formation. Combined with cold storage, 1-MCP fumigation offers an effective strategy for extending shelf life and maintaining quality in 'Thong Ploy' jackfruit.
Stevia (Stevia rebaudiana B.) is widely consumed for its medicinal properties and sweetening power. According to a hormesis curve, low doses of a stress factor can promote biostimulatory effects in plants. This research analyses the hormetic response of stevia plants (N = 90) to salicylic acid (SA) applied under greenhouse conditions. The methodology involved the evaluation of morphological variables, quantifying steviol glycosides (SGs) via HPLC, and analysing expression of key biosynthetic genes using qRTPCR. The results confirmed a dose-response effect of SA (0.1-0.5 mM), which optimised plant growth and modified gene expression, upregulating or downregulating signalling cascades, ultimately leading to higher accumulation of rebaudioside A, B, C, and dulcoside A. In contrast, higher concentrations (>3 mM) acted as distressors, inducing phytotoxicity and plant mortality. Specifically, 10 mM caused up to 100% mortality and severe leaf damage. This study concludes that controlled elicitation with SA is an effective biotechnological strategy to enhance the commercial quality, gene expression, and environmental stress tolerance of stevia crops.
Rootstock-scion interactions modulate nitrogen and carbon metabolism in Mangifera indica L. This study evaluated the temporal integration between nitrate reductase (NR) activity, total soluble carbohydrates (TSC), and flowering intensity in mango cultivars grafted onto contrasting rootstocks under semi-arid conditions. The experiment was conducted over two growing seasons in Petrolina, Brazil, using a randomised block design in a 3 & times; 4 factorial arrangement with three polyembryonic rootstocks and four scion cultivars. NR activity and TSC concentration were quantified in mature leaves at full flowering, and flowering intensity was expressed as the percentage of flowering branches. Rootstock & times; scion interactions significantly regulated NR activity and TSC accumulation, evidencing strong genetic and environmental modulation. A positive carry-over effect of NR activity on flowering was observed. Cultivar-specific physiological strategies were identified, with 'Kent' and 'Keitt' exhibiting greater metabolic efficiency, whereas 'Palmer' and 'Tommy Atkins' displayed more plastic responses.
The effect of manual flower thinning on vegetative growth, yield, and fruit quality of rainfed 'EarliGrande' peach (Prunus persica L.) trees was investigated during 2023 and 2024. Thinning improved vegetative growth, the number of flowers per shoot, fruit weight and quality. Heavy thinning led to the highest shoot length, number of leaves, fruit weight, and quality with lower yields compared with the control. Light thinning resulted in the highest number of flowers per metre and the lowest decline in yield compared with the control. Net returns for light and heavy thinning were the highest, reaching 'Egyptian Pounds (EGP)' 837.2 and EGP 853.0 per tree in 2023. In 2024, light thinning achieved the highest net return of EGP 1,594.5 per tree, compared with EGP 1,344.9 and EGP 1,253.8 per tree for heavy thinning and control, respectively. We recommend light thinning for optimal results in rainfed peach.
