陇东红富士果树养分回流对土壤表层管理的响应

地处陇东黄土高原的庆阳市苹果园普遍缺乏有效的土壤表层管理措施,以盛果期的"红富士"果树为对象,研究不同土壤表层管理方式在养分回流期对苹果树体贮藏养分的动态变化。研究结果表明:优化覆膜(T2)与优化覆草(T3)一年生枝条叶片的叶绿素含量均显著高于常规处理(T1)。T2和T3处理的一年生春梢、秋稍和封顶枝中的碳素贮藏物质(可溶性糖、淀粉)和氮素贮藏物质(总游离氨基酸、可溶性蛋白质)的含量均显著高于T1,T3比T2处理对碳素贮藏物质含量的提升效果更为明显。此外,相同枝条类型不同组织中的贮存养分含量不同,可溶性糖和可溶性蛋白质的含量表现为表皮积聚,韧皮部木质部,淀粉与总游离氨基酸含量表现为主轴积聚,木质部韧皮部。不同枝条类型中贮藏物质的含量整体表现为秋梢封顶枝春梢,秋梢在提升养分贮藏水平中起到了重要作用。

Response of nutrient backflux dynamics within Fuji trees to soil groundcover management approaches in East Gansu Province

Poor and insufficient groundcover-management approaches have been a big problem for apple production on Loess Plateau, Qingyang City, East Gansu Province. Soil groundcover management is a widely used soil-surface management measure. Soil groundcover management approaches can improve fruit tree nutrition, and nutrient backflux ensures that the trees efficiently use their nutrients, which is important for trees grown in an area with depleted soil nutrients. There are few reports about the effects of soil groundcover management approaches on nutrient backflux in apple trees. Therefore, we studied the effects of two different types of optimized soil groundcover management approaches on the dynamics of storage nutrients in Red Fuji apple trees in a fruit orchard during nutrient backflux and compared the results with those obtained using the local conventional management approach. The following three treatments were used: T1, the local conventional management measure; T2, optimized film mulching measure; and T3, optimized maize-straw mulching measure. We obtained the following results: Compared to the T1 treatment, both T2 and T3 treatments increased chlorophyll content, and this result was significant after T3 treatment. The chlorophyll content after T2 and T3 treatments was 5.53% and 7.94%, respectively. The two optimized treatments significantly increased the contents of both carbon storage substances (e.g., soluble sugar and starch) and nitrogen storage substances (total free amino acids and soluble proteins) in 1-year-old branches-spring shoots, autumn shoots, and top-cutting shoots; higher increments were observed in branches that received T3 treatment. Soluble sugars in spring shoots, autumn shoots, and top-cutting shoots increased by 8.94%, 8.16%, and 12.45%, respectively, after T2 treatment, and by 13.59%, 13.07%, and 15.10%, respectively, after T3 treatment. Starch in spring shoots, autumn shoots, and top-cutting shoots increased by 13.45%, 13.02%, and 9.63%, respectively, after T2 treatment, and by 20.73%, 22.32%, and 14.07%, respectively, after T3 treatment. Total free amino acids in spring shoots, autumn shoots, and top-cutting shoots increased by 34.43%, 26.81%, and 23.50%, respectively, after T2 treatment, and by 56.46%, 44.13%, 30.30%, respectively, after T3 treatment, Soluble protein in spring shoots, autumn shoots, and top-cutting shoots increased by 14.23%,7.17%, and 1.45%, respectively, after T2 treatment, and by 20%, 7.27%, and 1.27%, respectively, after T3 treatment. Different accumulating characteristics were observed for storage nutrients within different tissues in the same branch type. Overall, soluble sugars and soluble proteins exhibited obvious epidermal accumulation, and their levels were higher in the phloem than in the xylem; the contents of soluble sugar and soluble protein in the phloem were 54.52% and 152.64%, respectively. Starch and total free amino acids exhibited obvious central accumulation, and their levels were higher in the xylem than in the phloem; the contents of starch and total free amino acids in the xylem were 76.87% and 89.26%, respectively. The three branch types showed different levels of storage nutrients in the following order: autumn shoots > top-cutting shoots > spring shoots. Autumn shoots played an important role in improving the level of storage nutrients. Storage nutrient levels in autumn shoots and top-cutting shoots were higher (24.76% and 12.68%, respectively) than those in spring shoots.