Search

【Objective】 To provide reference basis for parents selection and matching of sugarcane breeding, the flowering habits of 12 newly introduced sugarcane parents from America were clarified. 【Method】 The initial flowering time, heading rate and pollen dyeing rate were investigated and analyzed in continuous 5 crossing seasons from 2013/14 to 2017/18. 【Result】 Broad-sense heritability of the initial flowering time, the heading rate and the pollen dyeing rate was 0.9518, 0.7961 and 0.9384, respectively. The parents with the earliest first flowering time were CP07-1618 and CP09-4448, and the parent with the latest first flowering time was CP07-2137. The latest flowering time for the 12 parents was in 2015/16 crossing season. There was no significant difference in initial flowering time among the parents in other crossing seasons. The parents with low heading rate were CP01-2390, CP07-2137 and CP09-4707, belonging to difficult flowering parents, and the rest of 9 parents were easy flowering parents. The parents with small pollen dyeing rates were CP00-1630, CP06-3458, CP07-1618, CP07-2137, which could only be used as female parents because their pollen dyeing rates were no more than 30% in all crossing seasons. The parents with high pollen rate were CP06-2422 and CP09-4448. 【Conclusion】 The broad-sense heritability characters of the initial flowering time, heading rate and pollen dyeing rate of sugarcane parents were high heritability, so the 12 parents could be selected strictly in the stage of crossing combination. [ABSTRACT FROM AUTHOR]

Objective] Studying the pathogenic bacteria of sugarcane brown stripe disease in Guangxi to provide scientific basis for scientific and effective prevention and control of sugarcane brown stripe disease. [Method] Using plant tissue isolation methods, pure cultures of the pathogenic fungus were isolated from diseased sugarcane leaves in Guangxi. Pathogenicity assays, morphological observations, and phylogenetic analysis based on polygenic nucleotides sequences (rDNA-ITS, GAPDH, LSU, EF-1α) were employed to identify the pathogen. Furthermore, the sensitivity of 9 fungicides on the pathogen were also tested in vitro using the mycelial growth rate method. [Result) A pathogenic fungus named GHT-01 was isolated from diseased sugarcane leaves. The fungus isolates were brown or black colonies with sparse white aerial myceli- um. The spores were solitary or clustered, straight or slightly curved, with three septum and four cells, the third cell being larger and darker in color than the others. The size of the conidia was 12.3 -24.1 µm x 5.2-12.8 µm. Multi-locus sequence analysis showed that it clustered with model strain of Curvularia lunata (CBS730.96, CBS157.34). Koch's postulates confirmed that symptoms induced by the pathogen on healthy sugarcane leaves and conidia morphology of the re-isolated fungus matched the initially isolated strain. Therefore, the pathogenic fun- gus was identified as C. lunata. Fungicide sensitivity assays revealed that the best antimicrobial effect was observed with 40% benpyrazyl e- ther emulsion +45% prochloraz emulsion, and their EC50 values were 1.43 and 1.54 µg/mL, respectively. In contrast, the antimicrobial effect of 60% oxazole ether metiram water dispersible granule was less effective, with inhibited medium concentration (EC50) values of 205.82 µg/mL. [Conclusion] The study represents the first identification of C. lunata as the pathogen of brown stripe disease in sugarcane in Guangxi. Additionally, 40% benpyrazyl ether emulsion + 45% prochloraz emulsion are identified as effective fungicides in inhibiting the growth of the pathogen. [ABSTRACT FROM AUTHOR]

[Objective] To understand the disease resistance of sugarcane parents, and the characteristics of disease occurrence, influencing factors, heritability of traits, and provide reference for disease resistance breeding in sugarcane. [Method] Two rounds of field disease resistance trial, including 463 sugarcane parents, were carried out in Dingdang Experimental Base of Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences ( hereinafter referred to as Dingdang), Experimental Base of Baise Agricultural Research Institute, Guangxi (hereinafter referred to as Baise) and Zizhong Experimental Base of Sichuan Institute of Agricultural Special Plants (hereinafter referred to as Zizhong), and analysis of variance, broad sense heritability calculation and cluster analysis were processed. [Result] There were 18, 17 and 15 sugarcane diseases were found in Dingdang, Baise and Zizhong, respectively. Except for mosaic and smut disease, the relatively severe diseases were brown stripe, red rot, ring spot, yellow spot and leaf blight disease, with a disease index greater than 10. 00. The result of analysis of variance showed that the significant influence factors of different diseases were different, and the proportion of interaction variance of most diseases was higher than that of main effect variance. In the joint analysis of variance within the experimental location, the disease with significant (P < 0. 05, the same as below) or extremely significant (P < 0. 01, the same as below) parental variance in Dingdang were ring spot, red rot, yellow spot, rust, brown spot, pokkah boeng and purple spot disease, in Baise were ring spot, yellow spot, red rot, pokkah boeng and leaf blight disease, in Zizhong was red stripe disease. The diseases with significant or extremely significant parental variance in all experimental locations were ring spot, yellow spot, red rot, leaf scorch and purple spot disease. The calculation of broad sense heritability showed that sugarcane white leaf disease was a medium heritability trait, white rash, rust, leaf spot, brown streak and leaf scorch disease were medium low heritability traits and leaf blight, red rot, pokkah boeng, purple spot, red streak, yellow spot, brown spot and banded sclerotial disease were low heritability traits. However, only ring spot, yellow spot, red rot, leaf scorch and purple spot disease had broad sense heritability in the joint analysis of variance, which could be selected through multi-year multi-location field trials. Parents from different breeding ages did not show sustained positive selection results, only brown stripe and leaf blight disease showed fluctuation; Parents from different sources had significant or extremely significant differences in the resistance to red rot, ring spot, eye spot and leaf blight disease, among them, the resistance of Guitang parents and Yuetang parents was poor, while the resistance of Taitang parents was good. The resistance of Ho parents to ring spot disease was good, while the resistance to red rot disease was poor; The CP parents had good resistance to ring spot and leaf blight disease, but poor resistance to red rot disease. Among the tested parents, 3. 02 % had better disease resistance, 26. 57 % had good disease resistance, 49. 03% had moderate disease resistance, 18.57% had poor disease resistance, and 2. 81% had poorer disease resistance. Among parents with good and better disease resistance, less than 10. 00% had good utilization performance in sugarcane breeding; Many parents with good utilization performance just had moderate disease resistance, even parents with poor or poorer disease resistance were widely used, affecting the improvement of sugarcane disease resistance breeding. [Conclusion] Sugarcane parents for disease resistance of ring spot, yellow spot, red rot, leaf scorch and purple spot disease could be selected through multi-year multi-location of field trials. Sugarcane parents susceptible to leaf scald, white leaf, white rash disease, red stripe, brown spot, brown stripe, banded sclerotial, pokkah boeng, rust, eye spot and leaf blight disease should be eliminated. Reasonable selection of sugarcane disease resistant parents and improvement of disease resistance evaluation methods are conducive to promote the improvement of sugarcane disease resistance breeding. [ABSTRACT FROM AUTHOR]

[Objective]The present paper aimed to understand the cold tolerance of sugarcane main parents and the change characteristics of cold tolerance evaluation related traits, and to provide reference for breeding cold tolerance sugarcane varieties and reducing the harm of frost to sugarcane production. [Method] A total of 102 parents were selected for natural frost test in 5 crops consisted of two plant cane( 2017P and 2019P) and 3-year ratoon crops(2018F, 2019S and 2020F) during 2017-2020 in Zizhong, Sichuan, a frost prone area. The correlation analysis, variance analysis, calculation of broad sense heritability and cluster classification were processed. [Result] It was found that there were differences in the types and degree of cold damaged traits among parents under low temperature environments, and ratoon cane was more vulnerable than plant cane. The damaged traits were significantly ( P < 0. 05 ) correlated with some agronomic characters under cold or light frost. The performance of damaged traits was affected by parent, year and their interaction. The damage rate of plant was a high heritability trait, which can be used to evaluate cold tolerance under cold and light frost. The damage rate of stalk length and internode were medium heritability traits, which were less affected by low temperature environments, and can be used to evaluate cold tolerance, and the damage rate of internode was slightly better than that of stalk length. The percentage of green leaves varies greatly among years, which can be used for cold tolerance evaluation under light or moderate frost. The percentage of parental variance decreased, and the heritability also decreased when combined data from different trials were used for variance analysis. Cluster classification showed that trials plant crops in 2017 and 2019 were not suitable for the evaluation of cold tolerance of parents. Among the tested parents, 58. 89% of the parents were identified as good or better cold tolerance and 23. 53 % as poor or poorer.[Conclusion] There are differences in the types and degree of cold damaged traits among parents under low temperature environments, and the cold tolerance of sugarcane belongs to medium to high heritability. The traits that can be used for cold tolerance evaluation are affected by the degree of low temperature. Mild and severe low temperature stress should be set for indoor cold tolerance test. [ABSTRACT FROM AUTHOR]