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Evaluation of Water Yam ( Dioscorea alata L.) Germplasm for Reaction to Yam Anthracnose and Virus Diseases and their Effect on Yield
Author(s) -
Egesi C. N.,
Odu B. O.,
Ogunyemi S.,
Asiedu R.,
Hughes J.
Publication year - 2007
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.2007.01273.x
Subject(s) - germplasm , biology , dioscorea rotundata , dioscorea , yield (engineering) , horticulture , sowing , plant disease resistance , veterinary medicine , agronomy , medicine , biochemistry , materials science , alternative medicine , pathology , gene , metallurgy
Use of genetic resistance is the most practical and economic way to manage major diseases of yams. In a search for sources of resistance, 40 water yam ( Dioscorea alata L.) accessions from Benin, Ghana, Nigeria and Puerto Rico were screened under natural disease infection conditions in Ibadan, Nigeria. The accessions were evaluated at 1, 3 and 6 months after planting (MAP) for severity of yam anthracnose and viral diseases. The effect of the pathogens on yield was also evaluated at harvest 9 MAP. There were significant differences (P < 0.001) between accessions for severities of anthracnose and viral diseases. Eight (20%) of them had lower anthracnose area under disease progress curves (AUDPC) values than the resistant check while 10 (25%) had AUDPC values below the trial mean. There were significant variations (P < 0.001) in yield components among the accessions. There was significant negative correlation of anthracnose severity with fresh tuber yield ( r = −0.51) and with number of tubers per plot ( r = −0.40). Similarly, significant negative correlations were observed of virus disease severity with fresh tuber yield ( r = −0.78) and number of tubers per plot ( r = −0.65). Linear regression models also showed that the fresh yield had significant negative relationships with anthracnose ( R 2 = 0.26) and viral ( R 2 = 0.62) diseases. The accessions identified as resistant constitute a valuable resource for breeding of resistant germplasm.