Studies of Some Economic Efficiency Evaluation Models

Research on the phenology of Bamboo, Pham Van Tich (1963) [26], shows that Bamboo rarely flowers, after flowering (also known as being stunted), the tree dies. Bamboo flowers rarely bear fruit and form seeds, the germination rate of seeds is very poor.

b) Research on bamboo breeding

Because the ability of Luong seeds to flower and germinate is very limited, so far, Luong has been propagated mainly by vegetative methods. People have studied vegetative propagation of Luong by many different methods such as: grafting, cutting, rooting and planting...

+ Breeding bamboo by grafting method:

The breeding of bamboo trees has been clearly stated in Decision No. 05/2000/QD-BNN-KHCN of the Ministry of Agriculture and Rural Development on promulgating industry standard 04 TCN on technical regulations for planting and exploiting bamboo trees. Bamboo forests can be planted by rootstock, stem cuttings, dead cuttings or grafted branches, of which planting bamboo forests by grafted branches is the most effective.[5]

The method of grafting branches was studied by Le Quang Lien since the 1990s [13]. The results showed that branches with aerial roots have better rooting ability than branches without aerial roots. Branches with aerial roots can be directly planted in the soil (can give a rooting rate of cuttings over 90%). However, because the number of branches with aerial roots is very small (accounting for 11.6%), the multiplication coefficient of this method is not high. The method of using plastic bags to cover the pot and soil + mud can be grafted for branches without aerial roots and gives a rooting rate of 97%. And when the grafted tree has rooted, it must be incubated and cared for for 4 - 6 months to meet the standards for planting. In addition, the age of the branch and the time of grafting also have a great influence on the rooting rate of the branch. In general, the age of the tree should be 3 years or older, the age of the grafted branch should be 6 - 8 months and the grafting time from April to August is best.

+ Breeding bamboo by cutting method:

Creating bamboo varieties by cuttings has been promulgated as a technical process (QTN. 15-79) according to Decision No. 1649 QD/KT of the Ministry of Forestry, now the Ministry of Agriculture and Rural Development, dated November 26, 1979 (Ministry of Forestry, 1979) [5]. With this method,

The material used for cuttings is branches, using rooting stimulants such as 2,4D (1 gram of the drug dissolved in 50 liters of water); 2,45T (1 gram of the drug dissolved in 55 liters of water); Sodium and potassium salts of 2,4D (1 gram of water dissolved in 40 liters of water). After soaking the branches in the stimulant (about 9 - 15 hours), they are incubated by being placed in moist sawdust or moist sand until they take root, then they are planted in the garden or in pots, waiting until the cuttings grow well and produce at least the first generation of bamboo shoots before being planted.

The method of propagating bamboo seedlings by cuttings has a fast multiplication coefficient, meeting the standards of forest seedlings. However, to do this requires a professional and thorough training. [5]

In addition to the two popular methods above, there are some other methods being applied by people in some localities, which are planting by root and large shoots (root shoots) (Nguyen Ngoc Binh, 1963) [2]. This method has the advantage of being simple, not having to go through the nursery cutting step, high survival rate, the root has many eyes so it can grow strongly and quickly for bamboo shoots right from the first year of planting. This method has been applied by people for a long time, especially in districts such as Lang Chanh and Ngoc Lac (Thanh Hoa province). The limitation of the method of planting by root and shoot is that it takes a lot of work to dig the root, the breeding coefficient is low, and it is only applicable within the household. In general, there are many different methods to breed Luong, but the most commonly applied method today is cutting by branches and grafting.

c) Research on techniques for planting and caring for bamboo

+ Research on planting techniques

The technique of planting Luong forest was researched by Nguyen Van Tich (Institute of Forestry Sciences) from 1962 to 1965.

From 1986 to 1990, the Center for Experimental Forestry Research, Cau Hai carried out the project "Research on transplanting Thanh Hoa Luong trees to the central region" led by Engineer Le Quang Liem. Among the results of the project, the technique of creating Luong Bang seedlings from cuttings is worth paying attention to. From those results, the area of ​​Luong in Thanh Hoa in 1973 was only 15,160 hectares, by 1980 it had increased to 40,000 hectares and by 2000.

In 2006, Thanh Hoa province had 65,942 hectares, of which 61,049 hectares were pure Luong forest and 4,893 hectares were mixed Luong forest with timber trees.[4]

Previous research results on Luong trees have been compiled and issued into technical regulations for planting and exploiting Luong forests. Typically, the Regulation on silvicultural technical solutions applied to timber and bamboo production forests (QN 14-92), technical regulations for planting and exploiting Luong trees (Industry Standard 04TCN22 - 2000) ... These documents clearly stipulate technical measures for planting and trading Luong forests, especially some technical measures such as breeding work, seedling standards, planting techniques, planting density, planting methods, planting season...[6]

+ Research on planting methods

Depending on local conditions, bamboo is planted as a pure forest, intercropped with agricultural crops, planted in a scattered manner or planted in mixed species with broadleaf trees.

If intercropping with agricultural crops: The distance between bushes is 5 - 6 m, between bushes, intercrop agricultural crops such as upland rice, cassava, corn, etc. (Nguyen Ngoc Binh, 1963) [2]. After about 2 - 3 years, Luong grows well and overwhelms the crops, so it is only advisable to intercrop agricultural crops within the first 2 years, then let Luong develop into a pure forest. Intercropping agricultural crops in the early stages not only brings economic efficiency to the people, but also combines the care and protection of Luong forests from being destroyed by livestock, and by-products after harvesting agricultural crops become a source of fertilizer for Luong forests.

Scattered planting of bamboo is often applied in scattered patches on fields or planted in hedges around family orchards. This method takes advantage of vacant land around gardens, fields, etc. However, bamboo trees are easily knocked down during storms.

The method of planting mixed species of bamboo with timber trees has the ability to increase the sustainability of the forest, stabilize bamboo production and limit the decline in soil fertility (Le Quang Lien and collaborators, 1990) [13]. However, choosing the tree species to plant with bamboo is a very important issue for the future development of bamboo. Function

The amount of humus, nitrogen, phosphorus, and potassium in the soil when planting mixed forests with broadleaf trees is much higher than when planting pure bamboo (Nguyen Truong Thanh, 2002).[23].

Some research projects have investigated the composition of regenerating timber trees under the canopy of depleted Luong forests to find native tree species suitable for mixed planting with Luong forests. Research results in Cau Hai, Phu Tho have found 6 species that can be planted under the canopy of Luong forests: re huong, chestnut, khao vang, oak phang, xoan dao, lim xanh (Nguyen Thi Nhung, 2004). [20]

Researching on the timing of intercropping bamboo with other timber species using mixed planting method, Nguyen Thi The (2005) [24] conducted 2 experiments on the timing of intercropping bamboo with Acacia auriculiformis at Ngoc Lac Forestry Research Station - Thanh Hoa, which was to plant mixed species of bamboo (300 bushes/ha) and Acacia auriculiformis (600 trees/ha) in rows at the same time and select existing Acacia auriculiformis forests to intercrop bamboo under the Acacia canopy.

Research results of Mai Xuan Phuong (2001) [21] on planting bamboo in a mixed method with black cassia and flower-shaped cassia in Lang Chanh - Thanh Hoa showed that the mixed planting model of bamboo and black cassia was more effective than other models in terms of yield, quality and protective effect.

+ Taking care of bamboo forest after planting

According to industry standard 04 TCN on technical regulations for planting and exploiting Luong trees issued by the Ministry of Agriculture and Rural Development under Decision No. 05/2000/QD-BNN-KHCN, after planting, Luong forests must be cared for for 5 years, 3 times a year in February to March, July to August and October to November. In the first year, in spring and summer crops, care is taken twice in July to August and October to November, in autumn crops, care is taken once in October to November.[6]

According to the research results of Nguyen Thi The (2005) [24], after taking care of the planted forest, although the tilled land was covered with plastic with the aim of keeping the soil moist and preventing fertilizer loss when fertilizing bamboo, the results obtained showed that

The results showed that the plastic mulching formulas had lower shoot growth coefficients and number of shoots per bush than the non-plastic mulching formulas.

d) Research on exploitation and harvesting techniques

+ Studies on the growth and development of bamboo shoots and bamboo trees

Research by Nguyen Ngoc Binh (1963) [2] On average, each day, the bamboo shoots grow 40-60cm in height and the diameter of the bamboo shoots remains almost unchanged.

The research results of Cao Danh Thinh (2004) [25] also showed that the diameter growth of Bamboo increased rapidly in the first 30 days after the bamboo shoots grew, after 30 days the diameter growth of Bamboo was relatively stable. However, during this period, the height growth of Bamboo continued to increase rapidly and reached a stable height after 100 - 110 days since the bamboo shoots grew. Thus, the growth of Bamboo reached a stable level in both diameter and height after about 110 days since the bamboo shoots grew. In the following period, the growth in diameter and height of Bamboo was almost insignificant.

Thus, the studies of the above authors have clearly shown the growth and development laws of bamboo shoots, however, the research on the ratio of bamboo shoots forming bamboo trees has not been mentioned by the authors.

+ Research on Stream Mining

Research on the intensity of Luong exploitation, Tran Nguyen Giang (1977) [9] showed that it is appropriate to apply a moderate cutting intensity (leaving 1, 2 year old trees) and the exploitation rotation is 2 years.

According to Mai Xuan Phuong (2001) [21], the appropriate exploitation method is to selectively exploit the age of the trees in the bush. The most suitable cutting age is from the 3rd year old tree, the remaining trees are the 1st and 2nd year old trees to lay and grow bamboo shoots.

e) Research on pests and diseases of bamboo

+ Bamboo pests:

Nguyen The Nha (2003) [20] discovered about 41 species of bamboo pests, belonging to 31 genera, 19 families, and 7 different orders. To prevent the above pests, it is necessary to apply