What are the different intercropping methods for Dictyophora echinovolvata and Polygonatum cyrtonema under a Castanea henryi forest?

Study on different intercropping methods of Dictyophora echinovolvata and Polygonatum cyrtonema under a Castanea henryi forest

Fund project: Integrated demonstration and promotion of key technologies for forest-fungus composite cultivation in the mountainous areas of southern Zhejiang (project number: 2014ts16)

From 2015 to 2016, the Central Science and Technology Project for the technical demonstration of two forest-fungus composite circular management models in southern Zhejiang was implemented in Qingyuan County. The project creatively combined the Castanea henryi forest-Polygonatum cyrtonema and Castanea henryi forest-Dictyophora echinovolvata composite management models to form a forest-medicine-fungus composite management model of "upper layer Castanea henryi + lower layer Polygonatum cyrtonema and Dictyophora echinovolvata", achieving very good results. Polygonatum cyrtonema is generally harvested after 3-4 a, with an input of 165,000 yuan·hm-2 over 4 a, and the average annual capital input is large. By interplanting Dictyophora echinovolvata, not only is land utilization improved, but it also serves to support the long-term with the short-term, reducing the pressure of capital input for Polygonatum cyrtonema under the forest. The large amount of fungal residue left after harvesting Dictyophora echinovolvata is a very good organic fertilizer, which can be manually applied to the Polygonatum cyrtonema planting beds, improving the soil structure and water and fertilizer conditions of the Castanea henryi forest land, accelerating the resource cycling rate, and promoting the growth of Polygonatum cyrtonema and Castanea henryi. Through research on the differences in Dictyophora echinovolvata yield, basic labor, and labor intensity among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under a Castanea henryi forest, the experiment aims to screen out planting methods for interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest that are suitable for actual production, and to provide technical reference for the "one mu of mountain, ten thousand yuan" under-forest economic management model actively promoted in Zhejiang Province.

1 Materials and methods

1.1 Overview of the experimental site

The experimental site was set up at the Polygonatum cyrtonema base under a Castanea henryi forest of Qingyuan County Yikang Agriculture and Forestry Technology Co., Ltd. in Yucun Village, Pingdu Subdistrict, Qingyuan County, Zhejiang Province. The geographical coordinates are 118°59′10.9″ E, 27°35′48.2″ N, altitude 409 m, and the horizontal terrace belt width is 2-4 m. Red soil, subtropical monsoon climate, annual average temperature 17.6 °C, average temperature in the hottest month (July) 26.9 °C, average temperature in the coldest month (January) 7 °C, annual average rainfall 1,746.9 mm, average annual relative humidity 77%, and average annual frost-free period 255 d. The stand is a pure Castanea henryi forest, consisting of superior families such as Youzhen, Huangzhen, and Wuke Changmang, with a stand age of 14 a, in the full production period; the current Castanea henryi ground diameter is 15.6±3.4 cm, tree height 6.2±1.4 m, average plant-row spacing 4.8 m×5.1 m, average crown width 6.3 m×6.5 m, and canopy density 0.7-0.8. Polygonatum cyrtonema was planted in November 2013 using the tuber propagation method, with plant-row spacing of 20 cm×40 cm; the planting beds were arranged perpendicular to the horizontal terrace belt, and after planting the bed surface width was 1-1.2 m, bed height 25-30 cm, and operation ditch width 30-40 cm.

1.2 Experimental materials

The cultivation material for Dictyophora echinovolvata was bamboo shaving material that had been composted and fermented for 40 d with a moisture content of 53%-56%. The bamboo shaving material was leftover material such as bamboo shavings and bamboo powder from local bamboo processing enterprises; the Dictyophora echinovolvata spawn was purchased from Gutian, Fujian, with a spawn specification of 14 cm×27 cm.

1.3 Experimental design and methods

A Polygonatum cyrtonema planting area under a Castanea henryi forest with basically consistent site conditions, slope aspect, and slope position was selected, and treatments of stacking planting, side planting, and ditch planting (full ditch planting, half ditch planting) were set up respectively. For each treatment, the material input area was >2 sq m, the material input amount was 37.5 kg·m-2, and the spawn was 2 bags·m-2. The planting methods for each treatment are as follows:

Stacking planting method: that is, planting Dictyophora echinovolvata on the surface of the Polygonatum cyrtonema bed. Spread Dictyophora echinovolvata cultivation material on the Polygonatum cyrtonema planting bed surface, with the material input range 20 m2 from the edge of the bed surface. Side planting method: that is, planting Dictyophora echinovolvata on the side of the Polygonatum cyrtonema planting bed. The material spreading width is from 1/2 of the operation ditch width to the outer edge of the bed surface, and the length is the length of the Polygonatum cyrtonema planting bed shortened by 20 cm at both ends.

Full ditch planting: that is, planting Polygonatum cyrtonema in the operation ditch perpendicular to the horizontal terrace belt direction. The material spreading length is the length of the Polygonatum cyrtonema planting bed shortened by 20 cm at both ends, and the material spreading width is the operation ditch width.

Half ditch planting: that is, the material spreading length for Dictyophora echinovolvata is 1/2 of the operation ditch, and the material spreading width is the operation ditch width.

Measurement method for the time of basic labor procedures per unit area for Dictyophora echinovolvata planting methods: for each planting method, the measured planting area was >5 sq m; the worker participating in the timing was the same person, and for each planting method, after a 30 min rest interval, the basic labor timing for the next planting method was carried out. Each planting method was divided according to different work contents into 6 procedures: clearing the garden (gathering dead branches, fallen leaves, and chestnut burs on the horizontal terrace belt into the material spreading area), spreading material, arranging material, sowing, covering soil, and spreading rice straw, with each procedure connected in sequential construction method. The time for each procedure was measured with a stopwatch and recorded.

Dictyophora echinovolvata cultivation management: after spreading material and inoculation for each treatment, cover with soil 6-8 cm. When the temperature is below 18 °C, cover with plastic film for mycelial growth; when the mycelia emerge from the soil and form rhizomorphs, remove the covering film and cover with rice straw or chestnut leaves; after a large number of fungus eggs appear, increase the water supply, spraying once in the morning and once in the evening; after one flush of Dictyophora echinovolvata harvest is completed, stop watering for 5-7 d, then apply one heavy watering to the bed surface.

Data collection: during the Dictyophora echinovolvata harvest period, harvest Dictyophora echinovolvata from each location, measure fresh weight, and record. Data processing and analysis: use Excel 2007 and SPSS 19.0 for data processing and analysis of variance.

2 Results and analysis

2.1 Differences in Dictyophora echinovolvata yield among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest

The yield of Dictyophora echinovolvata under different planting methods, from high to low, was: half ditch planting > full ditch planting > side planting > stacking planting (Table 1). Among them, the yield of Dictyophora echinovolvata under half ditch planting and ditch planting, and under side planting and stacking planting, differed by only 39.1 g·m-2 and 40.8 g·m-2, with no obvious difference; the yield of ditch planting (including ditch planting and half ditch planting, the same below) was 233.7 g·m-2 and 274.5 g·m-2 higher than that of side planting and stacking planting, with a relatively obvious difference. The analysis of variance result was that different planting methods had no significant effect on Dictyophora echinovolvata yield (F=1.419, P=0.307>0.05).

Table 1 Differences in Dictyophora echinovolvata yield among different planting methods of Dictyophora echinovolvata and Polygonatum cyrtonema under the forest / g·m-2

2.2 Differences in basic labor

time and labor intensity among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest

For the basic labor time per unit area of each planting method, stacking planting was the largest, side planting was next, and ditch planting was the smallest (Table 2). Among them, ditch planting saved 137 s·m-2 compared with stacking planting and 78 s·m-2 compared with side planting.

There were obvious differences in work intensity among the planting methods. Overall, work intensity was greatest for stacking planting, next for side planting, and smallest for interplanting. Taking the material spreading and soil covering procedures, which took up a relatively large amount of time, as an example, due to the limitation of the material spreading work surface and the short-distance vertical transport of cultivation material and soil covering material to the work surface, the work intensity of stacking planting was obviously greater than that of interplanting and side planting. The increase in labor intensity inevitably led to longer necessary rest time, thereby increasing the working time per unit planting area and reducing work efficiency.

Table 2 Differences in basic labor time among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest / s·m-2

3 Conclusion and discussion

1) There was no significant difference in Dictyophora echinovolvata yield among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest. However, overall, the yield of Dictyophora echinovolvata under ditch planting was higher than that under side planting and stacking planting, increasing Dictyophora echinovolvata yield by 12.4% and 14.9% respectively compared with side planting and stacking planting. Based on a Dictyophora echinovolvata planting area of 3,000 m2·hm-2 (the same below), the fresh yield of Dictyophora echinovolvata under ditch planting was 701.1 kg·hm-2 and 823.5 kg·hm-2 higher than that under side planting and stacking planting; based on a fresh Dictyophora echinovolvata drying rate of 10% and a dry Dictyophora echinovolvata selling price of 200 yuan·kg-1, the yield increase was 14,022 yuan·hm-2 and 16,470 yuan·hm-2 respectively. The use of ditch planting significantly increased Dictyophora echinovolvata yield, which has certain positive significance in production.

2) Among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest, ditch planting had the least labor input and the lightest labor intensity, followed by side planting, and stacking planting was the greatest. Compared with side planting and stacking planting, ditch planting reduced labor input by 114.2 h·hm-2 and 65 h·hm-2 respectively; based on an effective working time of 8 h/person·d and a labor wage of 150 yuan/person·d, ditch planting saved labor costs of 2,141 yuan·hm-2 and 1,219 yuan·hm-2 compared with stacking planting and side planting. When labor input and labor intensity are combined, the effect of saving labor costs is even more obvious.

3) Through research on the differences in Dictyophora echinovolvata yield, labor input, and intensity among different planting methods of interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under a Castanea henryi forest, the experiment shows that the ditch planting method had the highest Dictyophora echinovolvata yield, the lowest labor cost, and obvious economic benefits. For interplanting Dictyophora echinovolvata in Polygonatum cyrtonema under the forest, the ditch planting method should be selected. The differences in the promotion of Polygonatum cyrtonema growth by different planting methods require further study.