2. Conservation status of mulberry genetic resources in China

By MIAO YUNGEN
Department of Sericulture & Apiculture,
Zhejiang University, Hangzhou, 310029, P. R. China
E-mail: <[email protected]>

Paper contributed to Expert Consultation on Promotion of Global Exchange of Sericulture Germplasm Satellite Meeting of XIX th ISC Congress, September 21^st -25^th Bangkok, Thailand

Food and Agriculture Organization of the United Nations

1. Introduction

Silk industry was the main activity in China, especially in rural areas since ancient time, back to BC 3000. After liberation and the establishment of new China in 1949, China government took a series steps to rehabilitate the sericulture production and recovery from damage by Japanese in the second war.

At present China is the highest cocoon and silk production country in the world. Its cocoon and raw silk production accounts to 70% and 63% of the total production of the world.

Table-1 The world cocoon output (t)

In recent years many measures have been taken up in sericulture areas of China to increase the production of leaf and cocoon. Mainly

1. Evolution of season specific silkworm races and region specific mulberry varieties to meet the requirements of diverse agro climatic conditions throughout China, mainly for Zhejiang, Jiangsu, Sichun and Guangdong provinces, which sericulture concentrated areas.

2. Suggesting the new agronomic practices for mulberry cultivation and rearing methods, to increase the production.

Currently, the area under mulberry is 8964000mu (597600 hectare), around 20000000 families are engaged in rearing, eggs used for rearing are 13420000 boxes, cocoon production is 409000t, purchased cocoon quantity is 332000t (Table 3).

Generally, the leaf yield/mu is around 1500-3000 kg, the average cocoon output per mu is about 50-60 kg. In advanced rearing area, the cocoon output reached 120-150 kg; the highest recorded is 200 kg per mu.

Table-2 mulberry field of main sericultural areas(X 10000 mu)

* 1 Hectare=15 Mu

Table-3 cocoon output per mu mulberry field (kg/mu)

Mulberry germplasm is the special fortune for sericulturists, which is developed through natural and artificial selection (human activity). In addition, the technical exchange between different districts and countries further comes to abundant in the mulberry resources.

Mutation breeding

According to archaeological studies, as early as 3500 years ago, China has discovered mulberry culture techniques and extended abroad from B.C. 3 century.

In China, mulberry has grown naturally since the ancient times and now the following varieties are available in the country: Morus multicaulis Perr., Morus alba Linn., Morus bombycis Koidz., Morus atropurpurea Roxb., Morus mongolica Schneid., Morus mongolica var. diabolica Koidz., Morus nigra Linn., Morus australis Poir., Morus cathayana Hemsl., Morus yunnanensis Koidz., Morus mizuho Hotta., Morus laevigata Wall., Morus wittiorum Hand-Mazz., morus notabilis Schneid., Morus nigriformis Koidz etc.

Until the beginning of 20th century all the mulberry trees and plantations in China were of the local wild variety, characterizing with excellent adaptation to the climatic and soil conditions, but having too low leaf yield.

The breeding and selection mulberry was begun from the 30’s of last century. Sericulturists in Zhejiang and Sichuan sericultural areas conducted the mulberry single selection and collected local indigenous varieties, and then investigated their characteristics.

From the 50-60’s of last century, the national investigation and arrangement and evaluation of local varieties were carried out, and extended a lot of indigenous mulberry races. Successively selected the productive races from local varieties and lines, such as He Ye Bai, Tong Xiang Qing, Hu No. 197, Hong Chang Sang, Huang Sang 14, Zhuan Ge Lou, Nan 1, Kuei Sang, Bao Kan 61, Bei Sang 1, Ya Zhou Sang, Cha Sang, 7307, Lun Jiao 40, Kang Qing 10, Chang Le Sang, Fuo Tang Wao Sang, Hong Xin 5, Lie Ye Wao Sang, Qing Pi Huang Sang, Dao Zhen Sang, Xuan 792, Yang Sang 1, He Tian Bai Sang, Liao Sang 1, Yan Bian Lu Sang, Xuan Qiu 1, etc. These mulberry races played very important roles in improving production quality and quantity.

In this time, some mulberry races were bred and extended in main sericultural areas, such as, Yu 2, 711, Yu 151, Yu 237, Xin Yi Yuan, Nong Sang 9. At the same time, radiation breeding of mulberry was conducted and a lot of races were bred, such as, Shi Gu 11-6, shi 11, Fu 1, Fu 151, Ji 7681 etc.

Polyploid mulberry breeding was carried out from 60’s of last century, and extracted some tetraploid and triploid mulberry races basically.

During the period 1970-1980, the mulberry varieties such as YICHINOSE, XINYICHINOSE, Improved LESTUMIGAE, and JIANCHI etc introduced from Japan and SHENGLI from the former U.S.S.R. and QIUYU from D.P.R.K. Among them, TICHINOSE and XINYICHINOSE were used in Zhejiang and Jiangsu sericultural areas, and JIANCHI and QIUYU for Liaoning and Jilin provinces.

At last 2-3 decades, new mulberry accessions were created mainly by using the methods of line selection, experimental polyploidy, radiation breeding and hybridization. At present, China collected and is maintaining about 2600 copies of mulberry genetics resources in 24 Provinces national.

For example, in Zhejiang province around 200 mulberry varieties are being maintained, which was divided into 4 types according to the Leaf maturation time, i.e. early mature (25), middle matured (52), middle-late matured (38) and late matured (68). After strict evaluation, some varieties are selected as practical use, such as hou sang, bai pi hou sang, zao qing sang, wu pi sang (early matured), he ye bai, tuan tou he ye bai, hu sang 197, tong xiang qing (middle-late matured) etc. according to their leaf yield, leaf quality and resistance to bad environment (pest, disease, temperature and humidity etc)(see photo 1, 2).