Reducing the sink/source ratio of on-date palm plants during fruit growth has physiological and biochemical impacts on the shift in source-sink limitations.

BACKGROUND: The present study examined the impact of reducing the 'sink' on the 'source' in On-palms with a bunch number greater than eight. The capacity of leaves and fruit, as well as assimilate loading and unloading in phloem, restrict plant growth and yield. The study evaluated yield components, as well as photosynthetic and hormonal feedback, resulting from source-sink relationships. RESULTS: During the mid-Kimri, removing bunches from On-trees stabilized yield components and fruit size, suggesting that On-trees have a sink limitation. Bunch thinning boosted these indicators compared to normal trees with a bunch number between six and eight inclusive, indicating that On-trees had source limitations. In mid-Khalal, the treatments presented a type of source and sink limitation that is opposite to mid-Kimri. The thinning techniques addressed the source-sink limitation by adjusting the additional carbon allocation. This resulted in an increase of non-reducing sugars and starch in different organs, whereas reducing sugars decreased. These adjustments were made to reduce sucrose-phosphate synthase and sucrose synthase activity, raising invertase activity, lowering indole-3-acetic acid, zeatin, gibberellin, and abscisic acid hormone levels in fruits, as well as lowering trehalose production in organs. Levels of hormones, enzymes, and trehalose showed less variation during bunch thinning and source limitation compared to bunch removal and sink limitation. CONCLUSION: At Rutab, thinning types demonstrated the source limitation of On-trees. Bunch removal and bunch thinning by removing the source-sink limitation had the greatest effect on increasing yield components and fruit size, respectively. To improve the quality and quantity of fruit, it is important to use both thinning techniques simultaneously. © 2023 Society of Chemical Industry.

Defining date palm leaf pruning line in bearing status by tracking physiological markers and expression of senescence-related genes.

The physiological and molecular markers were evaluated for defining leaf pruning line in bearing status of date palm (Phoenix dactylifera cv. Mazafati). Our results showed that the higher expression of the chlorophyllase (Chlase) gene was concomitant with lower expression of chlorophyll synthase (ChlG) and oxygen-evolving enhancer protein (PSBO) genes in the 6-year-old leaf line. In addition, the 6-year-old leaf line resulted in a lower Hill reaction rate, chlorophyll a/b ratio, photosystem Ⅱ quantum efficiency, and photosynthesis rate. Also, lower expression and activities of catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX) was associated with higher malondialdehyde (MDA) and hydrogen peroxide (H2O2) accumulation in 6-year-old leaf line. These results suggested that the physiological maturity termination, senescence stage initiation, and source to sink transition could occur in 6-year-old leaves. Furthermore, delayed 5-year-old leaf pruning line adjustment in consecutive years could increase quantitative and qualitative yield loss, decrease water use efficiency, and promote alternate bearing and fruit abscission, which is considered a common problem of date growing areas. Further, the senescence-related markers in the alternate bearing trees pruned in pruning line 5 showed a tendency to normal trees. The five-year-old pruning line also resulted in the balance of bunching and loading the alternate bearing trees.

Delaying Broccoli Floret Yellowing by Phytosulfokine α Application During Cold Storage.

During postharvest life, broccoli suffers from floret yellowing confining its economic and nutritional value. The objective of the present study was to explore the mechanisms employed by phytosulfokine α (PSKα) at 150 nM for delaying floret yellowing in broccoli during storage at 4°C for 28 days. Our results showed that the higher endogenous accumulation of hydrogen sulfide (H2S) resulting from the higher gene expression and activities of l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) in broccoli floret treated with 150 nM PSKα may serve as an endogenous signaling molecule for delaying senescence. Moreover, the suppressed ethylene biosynthesis in broccoli floret treated with 150 nM PSKα might be ascribed to lower gene expression and activities of ACC synthase (ACS) and ACC oxidase (ACO). Furthermore, lower gene expression and activities of Mg2+ dechelatase (MDC), pheophytinase (PPH), and pheophorbide a oxygenase (PaO) might be the reasons for the higher accumulation of chlorophyll in broccoli floret treated with 150 nM PSKα. Based on our findings, exogenous PSKα application could be employed as signaling bioactive hormone for retarding floret yellowing of broccoli during storage at 4°C for 28 days.

Exogenous phytosulfokine α (PSKα) applying delays senescence and relief decay in strawberry fruits during cold storage by sufficient intracellular ATP and NADPH availability.

Herein, we employed exogenous phytosulfokine α (PSKα) for delaying senescence and lessening decay in strawberry fruits during storage at 4 °C for 18 days. Our results showed that the strawberry fruits treated with 150 nM PSKα exhibited lower expression of poly-ADP-ribose polymerase 1 (PARP1) gene, leading to a higher intracellular NAD+ availability, beneficial for a sufficient provision of intracellular NADP+ with the activity of NAD kinase (NADK). Moreover, higher activities of glucose 6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and methylenetetrahydrofolate dehydrogenase (MTHFD) may be the reason for the sufficient intracellular availability of NADPH in strawberry fruits treated with 150 nM PSKα. In addition, strawberry fruits treated with 150 nM PSKα exhibited a sufficient availability of ATP resulted from higher activities of succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO). Therefore, our results indicate that exogenous PSKα could be beneficial for delaying senescence and reducing decay in strawberry fruits during cold storage.

Enhancing stability of essential oils by microencapsulation for preservation of button mushroom during postharvest.

Fresh button mushrooms (Agaricus bisporus L.) are sensitive to browning, water loss, and microbial attack. The short shelf-life of mushrooms is an impediment to the distribution and marketing of the fresh product. Essential oils outstand as an alternative to chemical preservatives and their use in foods meets the demands of consumers for natural products. To resolve controlled release of oil and increase in antioxidant and antimicrobial activities, the oil was incorporated into microcapsules. Effects of microcapsulated thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) on quality of fresh button mushroom were compared. Physicochemical qualities were evaluated during 15 days of storage at 4 ± 0.5°C. All treatments prevented product weight loss and decrease in polyphenoloxidase and peroxidase activities during storage. Color and firmness, microbiological analysis, and total phenolic content caused the least change. With use of microencapsulated oils, mushrooms were within acceptable limits during 10 days of storage. Microencapsulated rosemary oil produced the highest beneficial effects and has potential to improve quality of button mushrooms and extend shelf-life.