This method can be combined with the family courtyard economic system and makes full use of the scattered land in Xishuangbanna. Furthermore, different families can adopt different methods of planting. Some families build simple shade houses with stakes, some add tall grasses or oil palm leaves to the roof of the shade house; some plant the vanilla directly under trees, whether mango (Mangifera indica), litchi (Litchi chinensis), Baccaurea ramiflora, or pomelo (Citrus maxima); some even plant the vanilla in the Hevea brasiliensis forest, and others plant them in the secondary forest. These courtyard planting methods require lower input and are easy to build with a sufficient supply of organic matter and good ventilation. Only shading and pruning need special attention. The area using this kind of planting method reached 16 ha in Xishuangbanna. Now only a few families still plant in this way.
Vanilla Cultivation Practices
Vanilla producers in the Yunnan and Hainan regions apply almost the same technologies to vanilla production (Zhou, 2000). The most commonly adopted vanilla cultivation system for commercial purposes is an intensive one under artificial shade house conditions. In order to adapt to this cultivation system and the specific climate in different regions, a whole set of mature cultivation techniques has been developed. Through exchanges and experience sharing, Hainan and Yunnan have developed similar cultivation technologies. However, some differences in skill and the actual implementation of cultivation techniques still exist among different companies. According to the actual production of vanilla under artificial shade house conditions in the Yunnan and Hainan regions, a brief introduction to vanilla cultivation and curing techniques is given below.
Generally, vanilla is propagated by means of stem cuttings or tissue culture. Cuttings for propagation should be taken from plants that are healthy, robust, and have not yet flowered. The cuttings are usually 40–60 cm in length with 4–5 nodes, or 20–30 cm in length with at least two nodes, with the length depending on the amount of vines available. If there are not enough cuttings available, vanilla can be propagated rapidly and abundantly by means of tissue culture using shoot tips and nodal segments as explants. After the necessary hardening and acclimatization, seedlings can be transplanted into soil. In order to avoid seedlings becoming entangled and to ensure they are convenient for management, seedlings should be tied to bamboo sticks of around 50 cm in length.
The construction of a vanilla plantation over a large area with an intensive cropping system includes not only the construction of the plantation itself, but also its supporting infrastructures, such as irrigation systems and living facilities for workers, and so on, which should be considered comprehensively and carefully, and planned and distributed according to actual situations. It is vital to the optimal growth of vanilla in the Xishuangbanna region to develop irrigation systems and to water vanilla plants in the dry season, especially from March to May.
The construction of a vanilla plantation mainly includes excavating fields into planting belts (ridges) and dividing these into units or zones along with the construction of artificial shade nets, vanilla stakes, and pipelines for the installation of the irrigation system, and so on. For ease of operation, the processes should be carried out in turn. A vanilla plantation site requires a slope of a certain gradient, which should not exceed 15°. The planting land should be excavated in planting belts at the same distance apart, so as to prevent soil erosion and to improve soil fertility and water supply, and the width of each planting belt should be 1–1.5 m. Materials such as angle steel, cement or wood columns, which are connected by iron wires or steel bars, are usually used as supports for the artificial shade net with 60–80% shade. Along the planting belt, at intervals of 1.8–2 m, cement or wood poles should be erected and fixed at a convenient height, and connected by iron wires or other materials into a row, which provides a trellis for vanilla plants to climb up. The recommended height of the trellis is around 1.5 m above the ground, and that of the shade net is at least 2.5 m.
After the plantation has been established, rooted seedlings from tissue culture plantlets or cuttings grown in nursery beds can be used for planting. Long cuttings can be planted in an optimal season, when plenty of vanilla planting materials are available. Two cuttings are usually planted beside each trellis column. According to the cuttings available, the density of cuttings can be up to 4000–9000 plants per hectare. Comparatively, at the same distance between rows, if more cuttings are planted along each planting belt, this will help to achieve and sustain greater vanilla plant vegetative biomass in the initial stages. The optimal planting time is immediately before the rainy season, at the beginning of June in the Xishuangbanna region, although the vanilla seedlings could be planted in the other months. The seedlings should be planted 5–10 cm below the surface of the soil, while their rootlets should be situated and distributed at or near the center of the planting belts, stretching along horizontally.
From the initial planting, vanilla plants—especially flowering adult plants—need meticulous care and painstaking management. Only in this way can the desired high yield and sustainable production be obtained. The regular management of a vanilla plantation consists of weeding, fertilizing, mulching, irrigating, vanilla pruning and trailing, and plant protection. A farmer can usually undertake a management workload of 0.4–0.7 ha of intensive vanilla plantation. More workers are of course needed for artificial pollination according to the number of flowers during the flowering season.
Artificial Pollination
Owing to the unusual structure of the flower, in other words the separation of the stamen from the stigma by the rostellum, pollination must be done artificially with a bamboo splinter. There are two methods of artificial pollination. The first one is to push up the rostellum under the stamens and then press the pollen sac into contact with the stigma. The second one is to remove the cap-like rostellum directly and then press the pollen mass to adhere to the stigma. The “pushing method” is commonly used in the Hainan region, and the “removing method” is used in the Xishuangbanna region of Yunnan. Artificial pollination should avoid injuring the stigma or dropping the pollen mass, for both the “pushing method” and the “removing method.”
Supplying Nutrients and Fertilization Management
Being a surface rooting plant, vanilla is greatly dependent on favorable mulching to obtain available nutrients. The mulch and decomposed organic materials are the main source of nutrients for vanilla plants, and are helpful in retaining sufficient moisture and forming a loose soil aggregate structure for the roots to spread. Reasonable manuring is vital to obtaining an early, high, and sustainable yield. According to the mulching materials available and the plants’ growth, manuring is usually combined with mulching. The fundamental principles of supplying nutrients and fertilization are the application of organic manures combined with chemical fertilizers, foliar spraying of chemical fertilizers, and correctly supplementing plants with trace elements, and so on. Mulches used and available in the main regions of China include the humus litter layer from the rainforest, coconut shells, wood chips, sugarcane bagasse, and rice straw. Some enterprises have researched and developed specialized vanilla fertilizers. In combination with the trimming of planting belts, mulching should be carried out at the end of the rainy season and completed before the cold season begins.