LIN Xiu-fang, WU Chun-ling, CHEN Qing-zheng, QI Jun-cheng, LIU Hai-dong, YE Wan-yu

Hezhou Branch of Guangxi Academy of Agricultural Sciences, Hezhou Academy of Agricultural Sciences, Hezhou 542813, PRC

Abstract The genealogical relationship and agronomic characters of 13 peanut varieties, breeded by Hezhou Academy of Agricultural Sciences, which had been authorized were analyzed. The results showed that 20 direct parents were involved in 13 varieties, 80% of which came from Guangxi and Guangdong Province. Shanyou 523 and Yueyou 193 were used for more times; The genealogical analysis of these certified varieties can be traced back to 30 ancestral parents, the proportion of which contained consanguinity of Fu Peanut and Shitouqi were 84.62%. This demonstrated that genetic basis was rather narrow and it was quite difficult to make a great breakthrough in breeding. Plant height, total number of branches and oil content changed very little, 100-pod weight and pod yield increased, whereas there was a downward trend in shelling percentage. Therefore, it is quite necessary to further broaden the germplasm basis of parents, enrich breeding methods, and continue to strengthen disease-resistant breeding and specific peanut breeding.

Key words Peanut variety; Pedigree; Agronomic character; Hezhou

1. Introduction

Peanut is one of the main oil crops in Hezhou, Guangxi Province. Research on crossbreeding of peanut started in the 1970s by Hezhou Academy of Agricultural Sciences (formerly known as Wuzhou Regional Agricultural Science Research Institute, Hezhou Regional Agricultural Science Research Institute, Hezhou Agricultural Science Research Institute). Until 2016, 13 peanut varieties had been bred and approved, which played a certain role in the development of peanut industry in China.

Pedigree analysis of peanut varieties is an important and basic work. Based on pedigree analysis, not only can we find out the rules of replacement and evolution of peanut variety, and summarize the rules of parental selection and matching in breeding process, but also find the important backbone parents in breeding[1]. China has done a lot of pedigree analysis on rice[2], wheat[3], corn[4], cotton[5], soybean[6]and other major crops. Pedigree analysis of peanut variety has been carried out in Guangdong[7], Jiangsu[8], Liaoning[9], Fujian[10], Jilin[11]etc. However, the pedigree analysis of 13 peanut varieties registered in Hezhou, Guangxi Province has not been reported. Now, the pedigree analysis and agronomic characters analysis of 13 peanut varieties were conducted to understand the genetic background of their parents and can provide reference for selecting ideal parents for peanut breeding.

2. Materials and Methods

2.1. Materials

13 peanut varieties approved by Hezhou Academy of Agricultural Sciences were selected as test materials. See Table 1 for its name, parent source and authorized number.

2.2. Methods

The variety information came from the website of Seed Management Station of Guangxi Zhuang Autonomous Region (www.gxzy.gov.cn), pedigree and derivatives variety information came from the National Peanut Data Center (http://www.peanutdata.cn/variety/). Pedigree tracing method was used to trace the source of genealogy and its genealogy.

3. Results and Analysis

3.1. Parent analysis of peanut variety

It can be seen from Table 1, 20 direct parents were involved in 13 peanut varieties. Of which, there were 10 peanut bred varieties, accounting for 50%, 9 intermediate materials, accounting for 45%, 1 farm variety, accounting for 5%. Compared with the other parents, Shanyou 523 and Yueyou 193 were used more in direct parents. There were 3 varieties bred with Shanyou 523 as direct parent, and 3 varieties bred with Yueyou 193 as direct parent. Of which, Heyou 9 and Heyou 11 were bred with the same parents, Zhanyou 12/891198×Yueyou 193. Wuyou 1, in addition to itself, it was the direct parent of 2 varieties.

Table 1 Authorized peanut varieties

All the 13 varieties were bred by hybridization, indicating that crossbreeding had always been the main method for peanut breeding in Hezhou, and the breeding mode was mainly the bred variety × intermediate material and the bred variety × the bred variety.

From the source of direct parents, 20 direct parent materials came from Guangxi, Guangdong, Fujian, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences and Peru. Among them, 10 came from Guangxi, accounting for 50% of all the direct parents; 6 came from Guangdong, accounting for 30% of all the direct parents; 2 came from Fujian, accounting for 10% of all the direct parents; 1 came from Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, accounting for 5% of all the direct parents; 1 came from Peru, accounting for 5% of all the direct parents. It indicated that the direct parents of Hezhou peanut varieties were mainly from Guangxi and Guangdong.

The 13 varieties could be traced back to 30 ancestors by genealogy (Fig.1). SHEN Y et al.[12]pointed out that Fu Peanut and Shitouqi had made great contributions to peanut breeding in China. Eleven of the 13 varieties contained consanguinity of Fu Peanut and Shitouqi, accounting for 84.62%; 9 varieties contained the genetic genes of Hexian Big Peanut, Tianjin Peanut, Yueyou 3 and NCAc17090, accounting for 29.63%. SONG C J et al.[13]analyzed the pedigree of peanut resistance to bacterial wilt and found that the resistance of the varieties mainly derived from three parents, namely India Huapi, Taishan Sanlirou and Xiekangqing. Local variety and wild germplasm were rich in resistance gene, such as A. cardenasii and Liuzhou Zhenzhudou. 13 varieties directly or indirectly used the above antibacterial wilt materials, therefore, most of the bred varieties contained genes resistance to bacterial wilt. Of which, Wuyou 4 and Wuyou 7 were the varieties with high resistance to bacterial wilt, which enriched the resources of peanut varieties resistance to bacterial wilt in China. Except for the above germplasm, the utilization rate of other ancestral parents was not high, which indicated that peanut varieties registered in Hezhou had narrow genetic basis.

3.2. Derived varieties with bred varieties as direct parents

Wuyou 1: It was a new peanut variety, which was bred using Hexian Mafeng Big Peanut as the male parent and Xiekangqing as the female parent in 1976. Hezhou Academy of Agricultural Sciences used Wuyou 1 to breed new peanut variety Wuyou 4 and Heyou 14 by bybridization, Guangxi Jinbaihe Seed Industry Co. LTD used it to breed new peanut variety Zhonghua 775 by crossbreeding with Zhonghua 117.

Wuyou 4: It was a new peanut variety with high resistance to bacterial wilt, which was bred using Wuyou 1 as the female parent and PI393518 with multi-resistance potential introduced from abroad as the male parent in 1982. Guangxi Doctor Garden Seed Industry Co. LTD used it to breed new peanut variety Qingnongyou 683 by bybridization.

Wuyou 7: In the 13 varieties, it was used to bred the most new peanut variety by hybridization until now. Hezhou Academy of Agricultural Sciences used Wuyou 7 to breed a new peanut variety Hehua 1; Crop Research Institute, Fujian Academy of Agricultural Sciences used it as female parent to breed new peanut variety: Fuhua 3 and Fuhua 8; Guangxi Jinbaihe Seed Industry Co. LTD used it as male parent to breed a new peanut variety Jiayou 8.

The genetic contribution rate of the above 3 varieties in their derived varieties was 50%. Up to now, the record that the other varieties was used to breed new peanut variety was not found in National Peanut Data Center.

3.3. Agronomic characters

As shown in Table 2, the plant height of the authorized peanut varieties was 35.0～67.4 cm with a average plant height of 54.75 cm. Of which, Hefeng 125 was the highest plant; Wuyou 4 was the shortest.

The total number of branches in each peanut variety was low, only 4.5～9 with a average value of 6.8. Heyou 10 had the most branches.

The average 100-pod weight of peanut was 174.24 g. Hefeng 125 had the maximum 100-pod weight, up to 211.3 g; while Wuyou 4 had the minimum 100-pod weight, only 134.0 g.

The average shelling percentage of peanut was 67.75%. Only the shelling percentages of Wuyou 1 and Heyou 9 exceeded 74.00%. Heyou 9 had the highest shelling percentage, up to 78.00%; while Heyou 15 had the lowest shelling percentage, only 62.80%.

The oil content of peanut was 49.06%～54.45% with a average value of 52.05%. Each peanut variety showed little difference in oil content with a variation of 5.39%. Wuyou 7 had the highest oil content.

Fig.1 Peanut family tree

Table 2 Agronomic characters and yield of authorized peanut varieties

Yield was one of the important indicators to evaluate peanut variety. The yield of 13 peanut varieties was 2 740.95～4 350.00 kg/hm2 with a average yield of 3 623.85 kg/hm2. Hefeng 125 had the highest yield. The yield of Wuyou series was all lower than 3 000 kg/hm2; the yield of Heyou 9～13 was 3 000～4 000 kg/hm2; the yield of other varieties all exceeded 4 000 kg/hm2.

4. Conclusion and Discussion

In the 20 direct parents, except for PI393518, most of them were the varieties or intermediate materials from southern regions. Hence, the bred varieties had a good ecological adaptability. However, due to the repeated utilization of backbone parents and the hybridization of bred varieties as direct parents, the genetic basis of bred varieties became narrow and it was difficult to make a big breakthrough in breeding. Therefore, in order to introduce good characters, improve the genetic diversity of varieties[14]and broaden the genetic base of parents, in addition to selecting the southern varieties with strong ecological adaptability and high quality as the parent, the varieties with large ecological type difference, distant genetic relationship and some special traits, such as disease resistance, high yield, high oil content, etc., should be selected as the other parent.

The peanut breeding method adopted by Hezhou Academy of Agricultural Sciences, which was the only conventional crossbreeding, was simple. With the development of science and technology, new breeding techniques were constantly emerging, such as induced mutation breeding, cell engineering applied to breeding, molecular marker assisted selection, transgenic breeding[15], etc. However, these new breeding techniques were not used in peanut breeding by Hezhou Academy of Agricultural Sciences. Therefore, In the future, it may be considered to combine crossbreeding with other breeding methods to select new varieties.

Previous peanut breedings have focused on increasing yields. Although the yield of bred varieties has been improved, the extention and application of new varieties are not enough[16]. No variety can be widely extended in the market as the main variety.

Peanut is a crop with high yield and high oil. However, constrained by cultivated land resources, the increase of peanut planting area is limited[17]. Thus, peanut breeding will be still to increase yield as a breakthrough in the future for a long time. With the changes in the market and the improvement of people's living standard, the demands for peanuts have become increasingly diversified. In the future, the breeding targets can be diversified. In addition to the emphasis on yield and resistance, the breeding of high-oil peanuts, high-oleic acid peanuts, fresh peanuts and health peanuts can be strengthened.