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- Author or Editor: Sheng Wu x
- HortScience x
Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide economical and environmentally safe ways to promote the precocious maturation of spine grape berries, the effects of riboflavin were investigated. Riboflavin affected the reactive oxygen species metabolism in spine grape berries by increasing superoxide radical production and the hydrogen peroxide content, and it impaired the activities of the antioxidant enzymes superoxide dismutase and catalase. Riboflavin also induced the upregulated expression of maturation-related genes in advance, and the earlier accumulation of anthocyanin and total soluble solids. Phenological observations revealed that the treated grape berries underwent a color-turning stage 9 days earlier than the control, and the maturation stage occurred 7 days earlier than the control. Thus, riboflavin may significantly promote the precocious maturation of spine grape berries.
Citrus huanglongbing (HLB), or greening, is the most destructive citrus disease worldwide and is threatening the sustainability of the industry in major citrus-growing regions. Various treatments have been proposed in the literature to manage the disease. We review such literature and conduct an economic analysis based on the reported treatment effects on fruit yield and quality to identify cost-effective management strategies. Our results suggest that, among the treatments we reviewed, broad-spectrum insecticides provide the only cost-effective strategy for mitigating the impact of the disease. Our findings and discussion should help growers, policymakers, and other stakeholders make informed decisions in the search for effective, sustainable, and environmentally friendly treatments and policies against HLB.
Photosynthetic physiology of Dendrobium nobile, Dendrobium pendulum, Dendrobium chrysotoxum, and Dendrobium densiflorum was studied. A bimodal diurnal variation of the net photosynthetic rate (Pn) was observed in the four Dendrobium species with the first peak [5.09 to 6.06 μmol (CO2) per m−2·s−1] ≈1100 hr and the second peak [3.83 to 4.58 μmol (CO2) per m−2·s−1] at 1500 hr. No CO2 fixation was observed at night. For all four Dendrobium species, the light compensation point (LCP) was 5 to 10 μmol·m−2·s−1, light saturation point (LSP) ranged from 800 to 1000 μmol·m−2·s−1, apparent quantum yield (AQY) was 0.02, and CO2 compensation points (CCP) and saturation point (CSP) were 60 to 85 μmol·mol−1 and 800 to 1000 μmol·mol−1, respectively. Carboxylation efficiency (CE) values ranged from 0.011 to 0.020. The optimum temperature for photosynthesis was between 26 and 30 °C. The measurement of Pn seasonal variation indicated that July to August had the higher Pn for Dendrobium species. Additionally, the chlorophyll a/b (Chl a/b) ratios of the leaves were 2.77 to 2.89. Measurement of key enzymes in the photosynthetic pathway indicated relatively high Ribulose-1,5-bisphosphate carboxylase (RuBPCase) and glycolate oxidase (GO) activities but very low phosphoenolpyruvate carboxylase (PEPCase) activities. It suggested that these four Dendrobium species are typical semishade C3 plants.
Oriental melon (Cucumis melo var. makuwa Makino) is a fruit with distinctive characteristics that is grown in Fuzhou, China. Fusarium wilt disease management remains a major challenge in the production of this fruit. Here, we performed seven field trials at four locations in Fuzhou, Fujian Province, China, to evaluate the control of fusarium wilt and yield of Oriental melons grafted on two Cucurbita rootstocks [Shengyan Tianzhen (SYTZ) and Nanzhen No. 1 (NZ1)]. During the growing seasons of 2008 to 2011, Oriental melons grafted on SYTZ and NZ1 exhibited dramatically reduced incidences of fusarium wilt disease and increased yields compared with nongrafted Oriental melons. Disease was only recorded in Trial 3 at Hongwei (2009), where plants grafted on SYTZ and NZ1 exhibited 1.05% and 1.1% infection, respectively. In the other six field trials, wilting was not observed at all. In comparison, the incidence of the disease in nongrafted Oriental melons ranged from 45.0% to 100.0%. The use of Cucurbita rootstocks improved the qualitative and quantitative carotenoid profiles, increasing lutein levels (12.7 and 10.8 μg·g−1 of fresh weight, respectively) and ζ-carotene and phytofluene amounts in fruit samples from SYTZ- and NZ1-grafted plants. In particular, the Liyu/NZ1 combination significantly increased β-carotene content ≈4-fold compared with nongrafted samples. In conclusion, Cucurbita rootstocks provided acceptable protection of Oriental melon cv. Liyu against fusarium wilt and improved the productivity and quality of fruits.
Soil salinity influences plant growth and crop yield significantly. Former studies indicated that uneven salt distribution in the root zone could relieve salt stress. But, how uneven salt distribution influences Na+ and Ca2+ concentration in the stem, leaf, and fruit and whether this influence would bring effects on fruit blossom-end rot (BER) still needs to be further studied. Under consideration of this, pot experiment with four treatments, T1:1, T1:5, T2:4, and T3:3, was conducted by setting the upper soil layer salinity at 1‰, 1‰, 2‰, and 3‰ and the lower soil layer at salinities of 1‰, 5‰, 4‰, and 3‰, respectively. Compared with the uniform salt concentration in the root zone (T3:3 treatment), the incidence of BER in the T1:5 and T2:4 treatments decreased by 60% and 35%, respectively. The fruit Na+ concentration and Na+/Ca2+ ratio were positively correlated with the incidence of BER. The value of the upper-root selective absorption Ca2+ over Na+ (SCa/Na(upper root)) for T1:5 was 0.8 times more than that of T1:1. The results showed that the incidence of BER was positively correlated with root dry matter and SCa/Na(root) weighted mean salinity. The overall results suggested that uneven salt distribution in the root zone could promote the Ca2+ absorption, Ca2+/Na+ ratio, and selective absorption Ca2+ over Na+ and consequently decrease the incidence of BER in tomato fruit.
Pear (Pyrus spp.) is the third-largest economic crop in China after apples (Malus pumila Mill.) and citrus (Citrus reticulata Blanco), and it is mainly cultivated by smallholders. Currently, the yield of Chinese pear ranks midlevel globally, with only 17.9 t⋅ha−1⋅year−1, which is lower than that of the United States (36.0 t⋅ha−1⋅year−1). However, the factors limiting pear production dominated by smallholders are unclear. We interviewed 75 smallholders about 18 yield-related indicators for pear-typical planting areas. The boundary line model was used to analyze the contribution of internal factors and dominant external factors affecting yield and to simulate strategies for increasing yield through the scenario analysis. The results showed that the average gap between the average and highest attainable yields for smallholders was 10.5 t⋅ha−1⋅year−1 in Luniao County. Among individual yield-limiting factors, chemical fertilizer nitrogen (N) input (13.3%) was the most significant, followed by the soil-available N content (12.0%) and leaf magnesium content (12.0%). Overall, the contribution of all soil factors (42.7%) was the largest compared with the other factor categories. However, the contribution of internal factors could not be ignored and accounted for 25.3% of the total. A scenario analysis showed that comprehensive strategies considering soil, management, and internal factors achieved the largest yield improvement (14%), as did reducing the fertilizer application rate (66%) compared with only using soil or leaf diagnosis methods. Therefore, integrated methods should be considered when developing pear orchard management measures and include soil, management, and internal factors.