**4.1.1 Choice of rootstock**

274 Soybean – Genetics and Novel Techniques for Yield Enhancement

innovation and genetic improvement of soybean and to promote the process of soybean new

There has been a long history of over 1400 years for application of distant-grafting to agricultural production. The earliest records was found in sixth century encyclopedia of Chinese agricultural knowledge-- "Essential skill to benefit the Qi-people", where it was recorded that the graft union with high survival rate between pearl and mulberry tree yielded the poor quality fruits while the graft union with low survival rate between pearl and jujube or pomegranate tree yielded the good quality fruits. After that, the grafts between different trees, flowers, vegetables and crops were recorded in many agriculturerelated books such as "Compendium of Materia Medica" and journals such as "Studies in

From the purpose of distant graft, it could be found that grafting was originally used to improve plant tolerance to cold, resistance to diseases and enhance quality of fruits in the woody trees cultivation and propagation. Since the discovery of inheritable variation induced by grafting, the distant grafts have been used to innovative plant resources and improve plant varieties. Now, the distant graft technology is not only an effective approach for creating new resources and breeding new varieties, but also an important means in plant

Broadly speaking, grafting is that the branch or bud or stem of a plant is grafted onto the stem or root of another plant, so that the two parts coming from different plants are connected together and grow into a complete plant. Distant-grafting is that the grafting is

The survived grafted plant, the whole scion and stock form a uniform conductive system, the stems and leaves developed by the scion and the root system of rootstock exchange for nutrient. Because the grafted plant is composed by two different individuals, where the roots of rootstock not only function to absorb water and minerals, but also function to synthesize organic acids and amino acids while the leaves of scion are the main organ for the synthesis of organic nutrients, both two parts are not mechanically combined but are an interdependent organic whole. Rootstock and scion each possess a specific function necessary for survival, and also affect the function of each other, including the synthesis of metabolites and the development of reproductive organs, which is consequently expressed

There have been many different graft methods developed from the long-term graft practices. According to the resource of scion, the graft methods can be classified into three categories: bud graft, branch graft and stem graft. But according to the grafting modes of stock and scion, the graft methods can be divided into three main categories: plug graft, cleft graft and splice graft. For plug graft, the lower or upper of stem of rootstock seedlings is made a hole by using of bamboo sticks, where the scion is inserted after its stem end is whittled into

varieties.

**2. History of distant graft** 

the History of Natural Sciences" and so forth.

physiology, pathology, genetic research.

**3.1 Definition of distant graft** 

in the progeny of scion seeds.

**3.2 Methods of distant graft** 

**3. Definition and methods of distant graft** 

carried out among different families/genus/species of plants.

The plants with tuber roots are suitable for distant grafting as rootstocks, such as ginger, lily, sweet potato, potato, yam, etc. In addition, other plants with thick stem are also appropriate for grafting as rootstocks, for example, castor, sunflower, sesame, maize, sorghum and so on.
