Abstract
No sugarcane cultivar is resistant to root-lesion (Pratylenchus zeae) nematode in Australia. Sugar Research Australia commenced a research project to evaluate new sets of accession lines derived from introgression breeding between wild relatives of sugarcane and commercial parents. No established method of assessment was available for comparing the resistance of sugarcane in the glasshouse. This study aimed to determine the most suitable assessment method for comparing resistance in accession lines. Two resistance parameters were measured, (i) number of nematodes per plant, and (ii) number of nematodes per g of roots. Nine screening trials were conducted from 2011 to 2020. Resistance parameter number of nematodes/plant had less variations within trials compared to nematodes/g roots, although both parameters were equally repeatable. Number of nematodes/g of root were negatively correlated (r = ‒0.29 to ‒0.86, p ≤ 0.001) with root biomass in all nine trials, and with shoot biomass in three out of seven trials (r = ‒0.23 to ‒0.31, p ≤ 0.05). In contrast, the number of nematodes per plant were positively correlated with shoot biomass (r = 0.25–0.53, p ≤ 0.05) in three out of seven trials and with root biomass (r = 0.17–0.27, p ≤ 00.05) in three out of nine trials. These results clearly indicated that nematodes per g root is related to reduction in root biomass and shoot biomass.
Highlights
Plant-parasitic nematodes are major pathogens to sugarcane worldwide (Ramouthar and Bhuiyan, 2018)
In 2011, a research project was commenced by Sugar Research Australia (SRA, formerly BSES) to determine the level of nematode resistance in the progenies derived from crosses between Erianthus spp. and Saccharum spontaneum lines with commercial sugarcane
This study examined the relationships of the parameters used to evaluate root-lesion resistance in sugarcane accession lines from 2011 to 2020 in Australia, and determine a suitable method that would provide reliable and repeatable results
Summary
Plant-parasitic nematodes are major pathogens to sugarcane worldwide (Ramouthar and Bhuiyan, 2018). Pratylenchus spp, predominantly P. zeae, are the most important ne matodes pests of sugarcane in Australia, found in all sugarcane regions, and can cause significant yield loss (Blair and Stirling, 2007; Blair et al, 1999a, b). Cultural methods such as crop rotations or fallow provide short-term control in plant crop, and nematode populations bounce back to a damaging level within 12 months when sugarcane is replanted (Stirling, 2008; Stirling et al, 2001). If an accession line has a smaller root system, the lower number of nematodes could be due to the limited root biomass available to the nematodes as a food source
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