Modelling population densities of root-lesion nematode (Pratylenchus thornei) from soil profile temperatures to choose an optimum sowing date for wheat in a subtropical region

2015 ◽  
Vol 183 ◽  
pp. 50-55 ◽  
Author(s):  
J.P. Thompson
2020 ◽  
Vol 110 (2) ◽  
pp. 505-516 ◽  
Author(s):  
J. P. Thompson ◽  
J. G. Sheedy ◽  
N. A. Robinson

The root-lesion nematode Pratylenchus thornei is a major pathogen of wheat (Triticum aestivum) in many regions globally. Resistance of wheat genotypes to P. thornei can be determined from final nematode population densities in glasshouse experiments but combining results across multiple experiments presents challenges. Here, we use a factor analytic method for multiexperiment analysis of final population densities of P. thornei for 1,096 unique wheat genotypes in 22 glasshouse experiments. The resistance to P. thornei of the genotypes was effectively represented by a two-factor model with rotation of the axes to a principal components solution. Principal axes 1 and 2 (PA1 and PA2) accounted for 79 and 11% of the genetic variance, respectively, over all experiments. Final population densities of P. thornei as empirical best linear unbiased predictors (PA[1+2]-eBLUPs) from the combined glasshouse experiments were highly predictive (P < 0.001) of final nematode population densities in the soil profile, crop canopy greenness (normalized difference vegetation index), and grain yield of wheat genotypes in P. thornei-infested fields in the Australian subtropical grain region. Nine categories of resistance ratings for wheat genotypes from resistant to very susceptible were based on subdivision of the range of PA(1+2)-eBLUPs for use in growers’ sowing guides. Nine genotypes were nominated as references for future resistance experiments. Most (62%) Australian wheat genotypes were in the most susceptible three categories (susceptible, susceptible to very susceptible, and very susceptible). However, resistant germplasm characterized in this study could be used in plant breeding to considerably improve the overall resistance of Australian wheat crops.


Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 296
Author(s):  
John P. Thompson ◽  
Timothy G. Clewett

Field experiments testing rates of various nematicides, with and without NPZn fertiliser, were analysed to investigate how root-lesion nematode (Pratylenchus thornei) affects growth and yield components of susceptible/intolerant wheat cultivars in a subtropical environment. Plant response to nematode attack was assessed by regression and principal components analyses of various plant parameters at different crop development stages, in relation to different nematode population densities in the roots and root-zone soil. Reduction in P. thornei population densities by nematicides resulted in increased numbers of tillers, plant biomass, N and P concentrations and uptakes, numbers of spikes and kernels, and grain yield. Grain yield was strongly correlated with number of kernels, biomass and number of spikes, and negatively correlated with number of P. thornei in the root-zone soil at stem elongation. This study showed that P. thornei damage to roots decreased wheat yield through limiting N and P concentrations and uptakes in plant tops causing poor growth that commenced early and continued through the life of the crop. Genetic, environmental and management factors that reduce population densities of P. thornei, and decrease the impact of the nematodes starting in early crop growth, will greatly increase spike and kernel numbers and grain yield.


Author(s):  
Md Motiur Rahaman ◽  
Rebecca S. Zwart ◽  
Thusitha W. T. Rupasinghe ◽  
Helen L. Hayden ◽  
John P. Thompson

2019 ◽  
Vol 133 (2) ◽  
pp. 635-652 ◽  
Author(s):  
Muhammad Shefatur Rahman ◽  
Katherine J. Linsell ◽  
Julian D. Taylor ◽  
Matthew J. Hayden ◽  
Nicholas C. Collins ◽  
...  

2021 ◽  
pp. 13-19
Author(s):  
Kirsty Owen

Abstract This chapter provides information on the economic importance, host range, geographical distribution, damage symptoms, biology and life cycle and interactions with other nematodes and pathogens of the root lesion nematode, Pratylenchus thornei, a severe and widespread threat to wheat production in the subtropical grain production region of eastern Australia. Some recommended integrated nematode management practices and future research for nematode resistance breeding are also presented.


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