Rust caused by Uromyces viciae-fabae is a major biotic constraint to field pea ( Pisum sativum L.) cultivation worldwide. Deployment of host-pathogen interaction and resistant phenotype is a modest strategy for controlling this intricate disease. However, resistance against this pathogen is partial and influenced by environmental factors. Therefore, the magnitude of environmental and genotype-by-environment interaction was assessed to understand the dynamism of resistance and identification of durable resistant genotypes, as well as ideal testing locations for rust screening through multi-location and multi-year evaluation. Initial screening was conducted with 250 diverse genotypes at rust hot spots. A panel of 23 promising field pea genotypes extracted from initial evaluation was further assessed under inoculated conditions for rust disease for two consecutive years at six locations in India. Integration of GGE biplot analysis and multiple comparisons tests detected a higher proportion of variation in rust reaction due to environment (56.94%) as an interactive factor followed by genotype × environment interaction (35.02%), which justified the requisite of multi-year, and multi-location testing. Environmental component for disease reaction and dominance of cross over interaction (COI) were asserted by the inconsistent and non-repeatable genotypic response. The present study effectively allocated the testing locations into various categories considering their “repeatability” and “desirability index” over the years along with “discrimination power” and “representativeness.” “Mega environment” identification helped in restructuring the ecological zonation and location of specific breeding. Detection of non-redundant testing locations would expedite optimal resource utilization in future. The computation of the confidence limit (CL) at 95% level through bootstrapping strengthened the accuracy of the GGE biplot and legitimated the precision of genotypes recommendation. Genotype, IPF-2014-16, KPMR-936 and IPF-2014-13 identified as “ideal” genotypes, which can be recommended for release and exploited in a resistance breeding program for the region confronting field pea rust.
Fusarium wilt (caused by Fusarium oxysporum f. sp. lentis) is the most crucial limiting variable for decreasing yield levels of lentils (Lens culinaris Medik.) around the world. A set of 20 diverse lentil genotypes comprising breeding lines and released varieties was evaluated, along with susceptible controls, for resistance to fusarium wilt through natural incidence for two continuous years (2010–11 and 2011–12) in six diverse lentil-growing environments in India. Analysis of variance showed that the effect of genotype (G) and environment (E) for disease incidence was highly significant. Among the three sources of variation, the biggest contribution in disease occurrence was accounted for by environment (54.68%), followed by G × E interaction (17.32%). The high G × E variation necessitated assessment of the genotypes at different locations (environments). GGE biplot analysis of the studied genotypes revealed that genotype PL 101 and released cultivar L 4076 had low levels of disease incidence. The sources of resistance to fusarium wilt have great potential for use in lentil-breeding programs. Another biplot of relationships among environments demonstrated that, among the test locations, Sehore and Faizabad, were the most effective for differentiation of genotypes. On the basis of discriminating ability and representativeness, the Sehore location appeared an ideal testing site for natural incidence of F. oxysporum f. sp. lentis.
Cercospora leaf spot (Cercospora canescens) is a major fungal disease which impedes mungbean production worldwide. Presence of wider host range with existence of pathogenic variability creates intricacy towards host‐pathogen dynamics. Moreover, environmental factors having crucial role in augmenting severity of this disease further complicate disease management. An attempt has been made for unfolding genotype x environment interactions towards identifying and validating durable resistant genotypes against cercospora leaf spot in multi‐environment testing. Preliminary screening with 246 genotypes under artificial epiphytotic condition was conducted to extract out a subset of 22 mungbean genotypes for further evaluation in field testing across six environments consecutively for two years. GGE biplot analysis detected significant environmental influence towards genotypic response and confirmed the presence of non‐crossover interaction with incoherent genotypic response, thus advocating the urgency for multi‐location testing. GGE biplot aptly identified “LGG 460” and “COGG 912” as “ideal” and “desirable” genotypes, respectively having durable resistance and genetic homeostasis and thus suggested for their utilization in future resistance breeding programme in mungbean against cercospora leaf spot.
Fernandez, M. R., Fox, S. L., Hucl, P. and Singh, A. K. 2014. Leaf spotting reaction of spring common, durum and spelt wheat, and Kamut under organic management in western Canada. Can. J. Plant Sci. 94: 929–935. A 3-yr field study (2010 to 2012) was conducted in southwest Saskatchewan to determine the reaction of common, durum and spelt wheat cultivars currently registered in western Canada, and of Kamut wheat, to the leaf spot disease complex (LS) under organic management. The genotypes selected for this study are often grown by organic producers in this region. Overall, the most common LS diseases observed had been observed in previous studies under conventional management in the same area. For all 3 yr, common wheat cultivars with the highest LS scores were AC Barrie, CDC Go, Superb, and Unity, while those with the lowest scores were AC Andrew, CDC Bounty and Lillian. For durum wheat, Kyle had overall the greatest LS scores. CDC Zorba had lower LS scores than the other spelt wheat, CDC Origin, and it also had the lowest LS levels of all genotypes in this study. Kamut wheat was similar to the common and durum wheat cultivars for LS severity. The relative presence of the most common LS pathogens isolated (Pyrenophora tritici-repentis, Phaeosphaeria nodorum, Phaeosphaeria avenaria f. sp. triticea, Cochliobolus sativus, Mycosphaerella graminicola) from each of the four wheat species in each of the three years is also presented and discussed.
Singh, A. K, Clarke, J. M., Knox, R. E., DePauw, R. M., Wise, I., Thomas, J., McCaig, T. N., Cuthbert, R. D., Clarke, F. R. and Fernandez, M.R. 2015. AAC Marchwell durum wheat. Can. J. Plant Sci. 95: 189–195. AAC Marchwell durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] is adapted to the durum production area of th Canadian prairies. AAC Marchwell is the first durum genotype registered for commercial production in Canada with the Sm1 gene for antibiosis-based resistance to orange wheat blossom midge [Sitodiplosis modellana (Gehin)]. It combines high grain yield, grain protein concentration, yellow pigment, test weight, and low grain cadmium concentration. AAC Marchwell has similar straw strength, plant height, and days to maturity as Strongfield. AAC Marchwell is resistant to leaf rust, stem rust, stripe rust, common bunt, loose smut, and common root rot. AAC Marchwell has end use quality suitable for the Canada Western Amber Durum class.
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