scholarly journals Impacts of Root-Lesion Nematode (Pratylenchus thornei) on Plant Nutrition, Biomass, Grain Yield and Yield Components of Susceptible/Intolerant Wheat Cultivars Determined by Nematicide Applications

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 296
Author(s):  
John P. Thompson ◽  
Timothy G. Clewett
Keyword(s):  
Grain Yield ◽  
Yield Components ◽  
Root Zone ◽  
Wheat Cultivars ◽  
Root Lesion Nematode ◽  
Population Densities ◽  
Poor Growth ◽  
Pratylenchus Thornei ◽  
Lesion Nematode ◽  
The Impact

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.

scholarly journals Resistance of Wheat Genotypes to Root-Lesion Nematode (Pratylenchus thornei) Can be Used to Predict Final Nematode Population Densities, Crop Greenness, and Grain Yield in the Field

2020 ◽  
Vol 110 (2) ◽  
pp. 505-516 ◽  
Author(s):  
J. P. Thompson ◽  
J. G. Sheedy ◽  
N. A. Robinson
Keyword(s):  
Grain Yield ◽  
Nematode Population ◽  
Root Lesion Nematode ◽  
Population Densities ◽  
Wheat Genotypes ◽  
Final Population ◽  
Pratylenchus Thornei ◽  
Principal Axes ◽  
Australian Wheat ◽  
Lesion Nematode

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.

Impact of the root-lesion nematode Pratylenchus goodeyi and mulch on the East African Highland banana crop performance in Kibuye, Western Rwanda

Nematology ◽  
2010 ◽  
Vol 12 (3) ◽  
pp. 349-356
Author(s):  
Svetlana Gaidashova ◽  
Dirk De Waele ◽  
Carine Dochez ◽  
Bruno Delvaux ◽  
Piet van Asten
Keyword(s):  
Plant Growth ◽  
Root Lesion Nematode ◽  
East African ◽  
Population Densities ◽  
Root Necrosis ◽  
Crop Performance ◽  
Lesion Nematode ◽  
The Impact ◽  
Banana Crop ◽  
Pratylenchus Goodeyi

AbstractThe effect of nematode root injuries on banana crop yield is very poorly known in higher parts of the East African highlands. This study assessed the impact of the root-lesion nematode, Pratylenchus goodeyi, on growth and yield of three banana cultivars (Musa spp. AAA-EA) in a field experiment involving nematicide and mulch applications at conditions of high altitude (about 1500 m). Plant growth, yield, root damage and nematode population densities were observed over three production cycles. Low to medium levels (≤50%) of root necrosis were associated with improved plant growth, whilst higher root necrosis (>50%) had no effect on plant growth. No significant reduction in bunch weight was associated with high root necrosis in any cycle and any of the three cultivars. Mulch significantly reduced root necrosis and P. goodeyi population densities. Bunch weight significantly increased in all mulched plots irrespective of root necrosis intensity. These results agree with those of earlier surveys in Rwanda that suggested little impact of P. goodeyi on banana yields. However, they challenge general perceptions and previous findings on the negative impact of root lesion nematodes on banana crop performance.

Wheat biomass and yield increased when populations of the root-lesion nematode (Pratylenchus thornei) were reduced through sequential rotation of partially resistant winter and summer crops

2014 ◽  
Vol 65 (3) ◽  
pp. 227 ◽  
Author(s):  
K. J. Owen ◽  
T. G. Clewett ◽  
K. L. Bell ◽  
J. P. Thompson
Keyword(s):  
Grain Yield ◽  
Crop Rotation ◽  
Yield Loss ◽  
Soil Depth ◽  
Wheat Yield ◽  
Broad Host Range ◽  
Root Lesion Nematode ◽  
Pratylenchus Thornei ◽  
Host Status ◽  
Lesion Nematode

The root-lesion nematode, Pratylenchus thornei, can reduce wheat yields by >50%. Although this nematode has a broad host range, crop rotation can be an effective tool for its management if the host status of crops and cultivars is known. The summer crops grown in the northern grain region of Australia are poorly characterised for their resistance to P. thornei and their role in crop sequencing to improve wheat yields. In a 4-year field experiment, we prepared plots with high or low populations of P. thornei by growing susceptible wheat or partially resistant canaryseed (Phalaris canariensis); after an 11-month, weed-free fallow, several cultivars of eight summer crops were grown. Following another 15-month, weed-free fallow, P. thornei-intolerant wheat cv. Strzelecki was grown. Populations of P. thornei were determined to 150 cm soil depth throughout the experiment. When two partially resistant crops were grown in succession, e.g. canaryseed followed by panicum (Setaria italica), P. thornei populations were <739/kg soil and subsequent wheat yields were 3245 kg/ha. In contrast, after two susceptible crops, e.g. wheat followed by soybean, P. thornei populations were 10 850/kg soil and subsequent wheat yields were just 1383 kg/ha. Regression analysis showed a linear, negative response of wheat biomass and grain yield with increasing P. thornei populations and a predicted loss of 77% for biomass and 62% for grain yield. The best predictor of wheat yield loss was P. thornei populations at 0–90 cm soil depth. Crop rotation can be used to reduce P. thornei populations and increase wheat yield, with greatest gains being made following two partially resistant crops grown sequentially.

scholarly journals Investigating the Impact of Root-Lesion Nematodes (Pratylenchus thornei) and Crown Rot (Fusarium pseudograminearum) on Diverse Cereal Cultivars in a Conservation Farming System

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 867
Author(s):  
John P. Thompson ◽  
Timothy G. Clewett
Keyword(s):  
Grain Yield ◽  
Soil Profile ◽  
Crown Rot ◽  
Tolerance Index ◽  
Initial Population ◽  
Fusarium Pseudograminearum ◽  
Conservation Farming ◽  
Pratylenchus Thornei ◽  
Fourth Experiment ◽  
The Impact

In two experiments on a farm practicing conservation agriculture, the grain yield of a range of wheat cultivars was significantly (p < 0.001) negatively related to the post-harvest population densities of Pratylenchus thornei in the soil profile to 45 cm depth. In a third and fourth experiment with different rotations, methyl bromide fumigation significantly (p < 0.05) decreased (a) a low initial population density of P. thornei in the soil profile to 90 cm depth and (b) a high initial population of P. thornei to 45 cm depth, and a medium level of the crown rot fungus, Fusarium pseudograminearum, at 0–15 cm depth to a low level. For a range of wheat and durum cultivars, grain yield and response to fumigation were highly significantly (p < 0.001) related to (a) the P. thornei tolerance index of the cultivars in the third experiment, and (b) to both the P. thornei tolerance index and the crown rot resistance index in the fourth experiment. In the latter, grain yield was significantly (p < 0.001) positively related to biomass at anthesis and negatively related to percentage whiteheads at grain fill growth stage. One barley cultivar was more tolerant to both diseases than the wheat and durum cultivars. Crop rotation, utilizing crop cultivars resistant and tolerant to both P. thornei and F. pseudograminearum, is key to success for conservation farming in this region.

The role of plant-parasitic nematodes in reducing yield of sugarcane in fine-textured soils in Queensland, Australia

2007 ◽  
Vol 47 (5) ◽  
pp. 620 ◽  
Author(s):  
B. L. Blair ◽  
G. R. Stirling
Keyword(s):  
Growth And Yield ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Lesion Nematode ◽  
Yield Responses ◽  
The Impact ◽  
Stalk Length ◽  
Plant Parasitic

Damage to sugarcane caused by root-knot nematode (Meloidogyne spp.) is well documented in infertile coarse-textured soils, but crop losses have never been assessed in the fine-textured soils on which more than 95% of Australia’s sugarcane is grown. The impact of nematodes in these more fertile soils was assessed by repeatedly applying nematicides (aldicarb and fenamiphos) to plant and ratoon crops in 16 fields, and measuring their effects on nematode populations, sugarcane growth and yield. In untreated plant crops, mid-season population densities of lesion nematode (Pratylenchus zeae), root-knot nematode (M. javanica), stunt nematode (Tylenchorhynchus annulatus), spiral nematode (Helicotylenchus dihystera) and stubby-root nematode (Paratrichodorus minor) averaged 1065, 214, 535, 217 and 103 nematodes/200 mL soil, respectively. Lower mean nematode population densities were recorded in the first ratoon, particularly for root-knot nematode. Nematicides reduced populations of lesion nematode by 66–99% in both plant and ratoon crops, but control of root-knot nematode was inconsistent, particularly in ratoons. Nematicide treatment had a greater impact on shoot and stalk length than on shoot and stalk number. The entire community of pest nematodes appeared to be contributing to lost productivity, but stalk length and final yield responses correlated most consistently with the number of lesion nematodes controlled. Fine roots in nematicide-treated plots were healthier and more numerous than in untreated plots, and this was indicative of the reduced impact of lesion nematode. Yield responses averaged 15.3% in plant crops and 11.6% in ratoons, indicating that nematodes are subtle but significant pests of sugarcane in fine-textured soils. On the basis of these results, plant-parasitic nematodes are conservatively estimated to cost the Australian sugar industry about AU$82 million/annum.

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