覆蓋與敷蓋處理之檬果根系分布調查

Abstract

The investigation was conducted on a 16% NE facing slope with sandy clay loam soils at Fengshan Tropical Horticultural Experiment Station. The purpose of this study is to find out mango root distribution as related to cover cropping and mulching by grass and legume. The results may provide information for cultivation and management ef mango orchard. Treatments compared include cover and mulching with bahia grass, strip cover and mulching with bahia grass, cover with hidigofera, mulching with weepinglove grassand clean cultivation as check. For each treatment, two mango trees of ten years old were selected for the study. Trench method and quadrat frame was employed for measuring vertical root distribution on soil profile and excavation for tracing the planar root extension was also made. The diameter of big roots was measured by caliper and fine roots estimated by frequency in a 10 x 10 em quadrat. Root distribution and extension were also sketched on section papers. The weight of roots was measured and soil horizons identified. The results obtained are summarized as follows: 1. The root forms of mango in respective treatment plot are quite similar: big vertical roots extend to 175 em deep and lateral roots are few and growing within 30 em of upper soil layer. 2. Profue fine roots are observed in indigofera plot, while maximum quantity of roots grown around stump in bahia grass cover and mulching plot is recorded. This indicates that cover crops may cause better fine root growth in upper soil layer. 3. In cover cropping plots more number of big roots, greater fine root index and higher frequency and wider extension were found at down slope side. This may be attributed to better soil conditions and more available water. 4. Better root growth and development is observed in plot of strip cover and mulching with bahia grass. Therefore, thispractice is more proper from the standpoint of root growth. 5. It is found twisted root system in indigofera covered plot. This may be due to toxic substances from indigofera roots and further study is needed.