Effects of Canopy Microclimate on Chinese Chestnut (Castanea mollissima Blume) Nut Yield and Quality

The relationship between canopy microclimate, fruit and seed yield, and quality in Xanthoceras sorbifolium

Xanthoceras sorbifolium has high oil content and important biomass energy value, but its development is limited by the problem of low yield. This study investigated the relationship between the canopy microclimate, fruit yield, and fruit quality of Xanthoceras sorbifolium. Difference between the distributions of canopy microclimate factors as well as fruit and seed parameters in the inner and outer canopies of the lower layer, as well as between the inner and outer canopies of the upper layer, were investigated for a period of one year. Canopy structure induced significant differences between canopy microclimate factors during various periods of the year. Light intensity and temperature of the outer and upper canopies were higher than those of inner and lower canopies. However, relative humidity showed an opposing trend. Light intensity was significantly and positively correlated with fruit set percentage, fruit yield, and seed yield. Temperature was significantly and positively correlated with fruit yield and seed yield, but significantly negatively correlated with the oil concentration of seed kernels. Fruit and seed yields significantly decreased from the outer to the inner canopy and from the upper to the lower canopy. Fruit set percentage in the outer canopy was also significantly higher than that in the inner canopy. However, oil concentrations in the seed kernels of the lower layer were significantly higher than those of the upper layer. Additionally, regression analysis was used to construct evaluation models for microclimate, fruit, and seed parameters. Regression equations corresponding to the association between single microclimatic factors during different periods and the fruit and seed parameters may provide a reference for canopy pruning and help develop an optimal regression model that may be used to predict and estimate fruit and seed parameters.

Natural Bioactive Substances in Fruits of Aronia melanocarpa (Michx.) Elliott Exposed to Combined Light-Type, Chitosan Oligosaccharide, and Spent Mushroom Residue Treatments

Greenhouse culture is a practical approach to obtain non-wood forest products from berry fruit at a higher efficacy than resource silviculture in natural understory. In this study, three-year old black chokeberry (Aronia melanocarpa (Michx.) Elliott 1821) seedlings were transplanted to a greenhouse where sunlight was complemented by red- (69.4% red, 30.2% green, 0.4% blue) and blue-color (15.3% red, 64.9% green, 19.8% blue) light-emitting diode (LED) illuminations. Half of the planting soils were amended by spent mushroom residue (SMR) (not amendment as the control) and half the seedlings were sprayed by chitosan oligosaccharide (CO) on leaves. All treatments can increase seedling height, but only blue light reinforces the basal diameter growth. Compared to sunlight, exposure to blue light can promote leaf nitrogen and phosphorus concentrations, superoxide dismutase activity, and fruit proanthocyanidin content. The combination with CO addition will further increase chlorophyl a content, acid phosphatase activity, and total phenolics in fruit. SMR amended can induce the steady state uptake of nutrients but failed to impact fruit quality. Overall, we recommend the combination of blue light LED illumination plus CO addition to culture black chokeberry for the purpose to gain natural bioactive compounds.