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Foliar spraying is employed in this study to test the effect of 5-aminolevulinic acid (hereafter 5-ALA), aqueous-organic solvents and their compounds on the quality of Rosa rugosa. The results showed that, compared with the control group (foliar spraying of fresh water), foliar application of 5-ALA or aqueous-organic solvents singly, or in combination, all have various improving effect on rose leaf area, flower diameter (indicating size of the flower), stem length, opening rate, flower color and the total biomass; foliar spraying of 5-ALA and aqueous-organic solvents jointly or mere 5-ALA both can increase the chlorophyll content of unit area leaf, while mere aqueous-organic solvents will decrease the unit area leaf chlorophyll content. The conclusion is that, joint foliar spraying of 5-ALA and aqueous-organic solvents will lead to the optimal result on the quality of Rosa rugosa by way of making full use of the mutually beneficial interaction between 5-ALA and aqueous-organic solvents. This finding no doubt, will shed light on the improvement of Rosa rugosa quality and benefit the future development of the Rosa rugosa industry.

Stand density directly affects the distribution of ecological factors such as light, heat, and water in forest communities and changes the diversity and structure of undergrowth species, thereby affecting soil health. Fine roots can provide water and nutrients to plants rapidly in the fierce competition of soil resources, so as to get rid of environmental factors. This study examined the fine-root responses of the Populus tomentosa clone S86 to three stand densities (plant &times, row spacing: 2 &times, 2 m, 4 &times, 3 m, 4 &times, 5 m). We measured the biomass, morphology, and nitrogen content of lower- (1&ndash, 3 order) and higher-order (&gt, 3 order) fine roots, and analyzed soil chemical properties in 10&ndash, 30 cm. The soil from the density (2 &times, 2 m) stands showed lower soil organic matter content, available nitrogen, available phosphorous, and available potassium than others. Obviously, lower and higher-order fine roots were different: biomass of the &gt, 3 order accounted for 77&ndash, 87% of the total biomass, 1&ndash, 3-order fine-root diameter around 0.28&ndash, 0.38 mm, while &gt, 3-order fine root were 1.28&ndash, 1.69 mm, the length of 1&ndash, 3-order fine root was longer than the &gt, 3 order, and root length density, specific root length, and nutrient content between the 1&ndash, 3 and &gt, 3 orders were different. At 2 &times, 2 m, 1&ndash, 3-order fine-root biomass was the highest, 132.5 g/m3, and the 1&ndash, 3-order fine-root length, diameter, surface, root length density was also the highest, at the same time, the 1&ndash, 3-order fine-root total nitrogen and organic matter content was also the highest, while the &gt, 3 order was highest under 4 &times, 3 m or 4 &times, 5 m. The findings of this study show that stand density affected the available nutrient content of the soil. When soil resources were poor, the biomass, morphology, and chemical content of fine roots were adjusted to increase the nutrient absorption rate, particularly in the lower-order roots.