Effects Of Interplanting Grass On The Growth Of Apple Saplings And Absorption, Utilization Of Nitrogen And Phosphorus

The study was carried out in orchard of Shandong Agricultural University fruit research station from 2012 to 2013. Two-year-old ‘Red Fuji’/Malus hupenensis apple saplings,Trifolium repens Linn., Lolium perenne L. and Vulpia myuros C.were used to explore effects of grass interplantation on growth of the apple trees, and absorption and utilization, loss and residue of nitrogen in the 0-60 cm soil layer of the orchard, using the 15N-labeled tracer method. Meanwhile, two-year-old ‘Red Fuji’/Malus hupenensis apple saplings, Festuca elate Keng, Medicago sative Linn.and Poa pratensis L. were used to explore effects of grass interplantation on growth of the apple trees, and absorption phosphorus, soil available phosphorus changes on high phosphorus conditions fertilization treatment.The main results were followed:1. The effect of planting herbage on the growth and absorption of 15N-urea of apple saplings were explored in the study. The results showed that, compared with apple monocrops,the biomass, nitrogen acquisition and 15 N utilization rate of apple saplings were significantly reduced by planting herbage which was especially true under low nitrogen treatment in spring shoots growth arrest stage; While in autumn shoots growth arrest stage, compared with apple monocrops,the biomass, nitrogen acquisition,15 N utilization rate and root activity of apple saplings were significantly increased by planting herbage.In autumn shoots growth arrest stage, the15 N abundance and total N% content in 0-20 cm layer were Trifolium repens Linn.planting > Vulpia myuros C. planting > Lolium perenne L. planting > apple monocrops, but in20-40 cm and 40-60 cm layer the15 N abundance and total N% content were apple monocrops> Lolium perenne L. planting > Vulpia myuros C. planting > Trifolium repens Linn.planting. It indicated that leaching loss of nitrogen fertilizer was reduced by planting Trifolium repens Linn., Lolium perenne L. and Vulpia myuros C. Gmelin, which benefiting soil fertility remaining but also increasing the nitrogen efficiency, promoting the growth of apple saplings.2. The effects of interplanting grass on utilization,loss and accumulation of 15 N in apple orchard were explored in the study. The results showed that, compared with the apple trees in the plot without grasses interplanted, the trees in the plot with grasses interplanted were found to have an increasing trend in total fresh weight of a plant, thickness and length of new shootsand root-shoot ratio; The effect on root length, roots length density and roots surface area of apple trees was the most significant in the plot interplanted with Trifolium repens Linn., which was followed by the plot with Vulpia myuros C. and the plot with only apple the last; Nitrogen utilization rate also varied sharply between plots, being the highest in the plot with Trifolium repens Linn, which was followed by the plot with Vulpia myuros C. and the plot with only apple in the end; In the plots interplanted with herbage15 N residue was found mainly in the0-20 cm soil layer, and higher in content than that in the 0-20 cm soil layer in the plot of apple only. However, the amount soil of residual15 N in the 20-40 cm and 40-60 cm soil layers was the highest in the plot with apple only, which was followed by the plot with Lolium perenne L., and the plot with Trifolium repens Linn. in the end. In terms of nitrogen loss rate, the four plots displayed an order of apple only > Lolium perenne L. > Vulpia myuros C. > Trifolium repens Linn.. In short, all the findings indicate that planting Trifolium repens Linn., Vulpia myuros C. and Lolium perenne L. in apple orchards improves nitrogen utilization rate and consequently reduces nitrogen loss rate by a certain degree.3. The effect on phosphorus absorption and soil phosphorus accumulation risk mitigation condition under planting herbage in the study. The results showed that, compared with apple monocrops, the biomass and absorption phosphorus of apple saplings were significantly increased by planting Medicago sative Linn.and Poa pratensis L.. The highest dry weight and absorption phosphorus of apple saplings were planting Medicago sative Linn. on high phosphorus treatment, as 70.97 g and 0.42 g/plant respectively; While inhibition can be seen on growth and phosphorus absorption of apple saplings by planting Festuca elate Keng.Phosphorus absorption ability of herbage was significantly affected by phosphorus application levels. Compared with the low phosphorus condition, high phosphorus treatment significantly increased the phosphorus content and phosphorus accumulation of three kinds of herbage, and the phosphorus content were Medicago sative Linn.> Festuca elate Keng > Poa pratensis L.,while the phosphorus accumulation were Festuca elate Keng > Medicago sative Linn.> Poa pratensis L.. Compared with apple monocrops, the phosphorus content in 0-20 cm and20-40 cm layer significantly reduced by planting herbage and the maximum reduction was Medicago sative Linn. planting treatment, followed by Festuca elate Keng planting treatment,while the minimum reduction was Poa pratensis L. planting treatment under high phosphorus conditions. Therefore, planting herbage was expected to be the effective measure that could improve the orchard soil phosphorus accumulation problem if selecting appropriate herbage planting management model according to the herbage biological characteristics.