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Plant biostimulants have received increasing attention in recent years because of their positive effects on crop performance and contribution to agro-ecological sustainability. The aim of this study was to determine the influence of betaine and chitin treatments, alone and in combination, on lettuce plants by changes in the morphology and physiology of plants exposed to regulated deficit irrigation (RDI). Plants were subjected to full irrigation (FI; no water deficiency treatment, field capacity >70%) and RDI (field capacity <50%) conditions until the end of each experiment. We recorded plant yield–related traits, net photosynthesis, and water use efficiency (WUE) values weekly for 4 weeks and carried out three individual experiments to assess the efficacy of biostimulant and irrigation treatments. Betaine (0, 50, and 100 mm/plant) was foliar-treated every 2 weeks during Expt. 1, whereas chitin (0, 2, and 4 g/kg) was applied to the soil at the beginning of Expt. 2. We then applied the optimal concentration of each chemical alone or in combination to the plants as Expt. 3. Compared with negative control, the application of 50 mm betaine and 2 g/kg chitin significantly increased leaf area (LA) per plant by 48.5% and 25.6%, respectively. Furthermore, 50 mm betaine and 2 g/kg chitin treatment showed a clearly protective effect in RDI plants, enhancing their total fresh weights by 26.10% and 75.0%, respectively, in comparison with control. Comparing WUEyield and WUEbiomass, chemical-treated plants had higher values than control. Betaine (50 mm) or chitin (2 g/kg) treatments alone significantly elevated LA, fresh shoot weight, total fresh and dry weights, net photosynthesis, and WUE values, and boosted the water stress tolerance of lettuce under RDI compared with controls. However, a combined treatment of 50 mm betaine and 2 g/kg chitin did not increase the levels of all yield traits under RDI compared with individual chemical treatment. Most leaves appeared healthy, green, and had visually less leaf chlorosis when treated with chitin or betaine under RDI compared with untreated plants subjected to RDI. Our study indicates that applying betaine and chitin improves plant performance against water supply limitations and highlights their potential for the sustainable production of lettuce.
Loropetalum chinense, one of three species in its genus in China, is distributed primarily in Hunan and Jiangxi Provinces. By establishing a Loropetalum gene bank and reviewing research on its varieties, genetic traits, and genetic diversity, we hope to promote the full yet sustainable use of this valuable, regionally varied natural resource. Our results will help promote the development of a broader resource economy.
Exogenous application of either salicylic acid (SA) or calcium chloride (CaCl2) to alleviate heat stress has been extensively studied. However, the effects of combined SA and CaCl2 treatment on the heat tolerance of poinsettia have been poorly studied. This study investigated the role of a foliar spray comprising SA and CaCl2 in managing heat tolerance of three poinsettia (Euphorbia pulcherrima Willd.) cultivars, Noel, Winter Rose (WR), and Ice Punch’ (IP). Plants were pretreated with SA, CaCl2, or combined SA and CaCl2 and then exposed to a temperature of 42 °C for 1 hour. Changes in the relative injury (RI) percentage, malondialdehyde (MDA) content, and antioxidant enzyme activities were determined. All plants were then placed in an environment-controlled greenhouse for 14 days and evaluated. Lateral bud sprouting (%), new leaf numbers, and phenotypic appearance were recorded. Results revealed that the three poinsettia cultivars varied in their appearance, morphological growth patterns, and ability to tolerate high-temperature stress. Plant growth of ‘Noel’ was more robust than that of ‘WR’ and ‘IP’, which were considerably affected by heat stress, resulting in brown, withered leaves and defoliation. In general, the effects of the combined application of SA and CaCl2 on heat-tolerant ‘Noel’ were superior to those of individual applications and no treatment (for control groups) in terms of the RI percentage, lateral bud sprouting (%), and appearance under heat stress. Application of combined SA and CaCl2 for ‘Noel’ plants was more beneficial for enhancing catalase activity and resulted in the effective alleviation of decreased malondialdehyde content under heat stress. Treatment including 200 μΜ SA and 10 mm CaCl2 may alleviate heat stress and may prove useful in breeding programs focused on improving poinsettia cultivars.
Red leaf lettuce (Lactuca sativa) has high nutritional value and is frequently used in salads. In a plant factory with full electric lighting, if the spectrum is incorrect, then red leaf lettuce will have incomplete coloration. This study aimed to establish a light recipe for the mass production of red leaf lettuce using electric light sources in a plant factory by using indicators for quantitative assessment, including energy yield (EY) [grams of fresh weight (FW) harvested per kilowatt hour of electricity input for lighting], photon yield (PY) (grams of FW harvested per mole of photons delivered), anthocyanin yield per kilowatt hour (EYA), and anthocyanin yield per photon (PYA). First, the effects of four types of light quality on FW and anthocyanin content were examined. Then, two types of light quality, light-emitting diode with a red-to-blue photon ratio of 80:20 (R80:B20) and R20:B80, were selected for an experiment involving five treatments. An optimum light recipe (SR5SB1) including R80:B20 treatment during the early stage of cultivation (weeks 1 through 5 after sowing) followed by R20:B80 treatment during the final stage (week 6) was proposed. The SR5SB1 treatment led to FW, EYA, and PYA of 87.8 g/plant, 1.63 mg/kWh, and 0.57 mg·mol–1, respectively. This treatment resulted in the highest EYA and PYA, with 159% and 256% more anthocyanin productivity, respectively, compared with cool white treatment (with FW, EYA, and PYA of 65.8 g/plant, 0.63 mg/kWh, and 0.16 mg·mol–1, respectively). The proposed SR5SB1 light recipe enabled cultivation of red leaf lettuce with a balanced yield and anthocyanin production.
Golden camellia flowers are treasured for their unique yellow color and bioactive chemical compounds. Because of its high market demand, there is strong interest in inducing early flowering in golden camellias for earlier harvest. Previously, we have successfully induced flowering in Camelia chrysantha (Hu) Tuyama juvenile grafted plants and seedlings with paclobutrazol (PBZ). During this study, we investigated the efficacy of PBZ on C. tamdaoensis juvenile rooted cuttings. C. tamdaoensis is a yellow-flowering camellia species that is native to Vietnam and valued by the local population. It was found that applications of 100 and 200 ppm PBZ generated an average of 13 and 30 flowers per 5-year-old plant, respectively. None of the control plants flowered. The average flower diameter was 17.2 cm for 100-ppm-induced flowers and 26.0 cm for 200-ppm-induced flowers. The dynamics of various phytohormones (indoleacetic acid, abscisic acid, salicylic acid, and jasmonic acid) were altered by PBZ treatment. It is suggested that low indoleacetic acid, high abscisic acid, and jasmonic acid and a gradual increase in salicylic acid benefit floral initiation of golden camellias. The study provided the first insight regarding the action mechanism of PBZ for the initiation of camellia flowering.
Amorphophallus species are one of the main economic crops in the mountainous areas of southwest China. However, soft rot disease (Pectobacterium carotovorum ssp. carotovorum) is devastating for this crop. This study explored the Amorphophallus resistance mechanism against soft rot disease by analyzing transcriptome data using a weighted gene coexpression network analysis. The RNA sequencing of plants infected for 0, 12, 24, and 48 hours produced a total of 52.25 Gb of clean reads. A total of 29,096 genes were divided into 34 modules. Six modules of interest with the highest correlation with the target traits were selected to elucidate the resistance genes and pathways. The selected modules were enriched in the α-linolenic acid metabolism, phenylpropane biosynthesis, plant hormone signal transduction, and plant pathogen interaction pathways. Ultimately, AmBGLU, AmCAML, AmCDPK, AmLOX, and AmRBOHD were identified as genes of interest in the four significantly related metabolic pathways for real-time fluorescence quantitative polymerase chain reaction verification. The determination of salicylic acid (SA) and jasmonic acid (JA) in Amorphophallus muelleri and Amorphophallus konjac that suffered from soft rot disease showed that SA and JA were involved in the A. muelleri and A. konjac defense response against soft rot disease. Methyl jasmonate treatment delayed the onset of A. konjac soft rot disease. This study provides a reference for the interaction between Amorphophallus species and soft rot disease and the breeding of broad-spectrum and specific Amorphophallus cultivars that are resistant to soft rot disease.