Abstract
In the subtropical grain region of eastern Australia, two experiments were conducted, one initially with 2490 P. thornei/kg soil, the other with 8150 P. thornei/kg soil at 0–0.9 m soil depth. We determined the effect of P. thornei, residual from a weed-free fallow and pre-cropping with several cultivars each of barley (Hordeum vulgare), faba bean (Vicia faba), chickpea (Cicer arietinum), and wheat (Triticum aestivum) (Phase 1), on the growth of wheat cultivars with intolerance or tolerance to P. thornei (Phase 2). Pratylenchus thornei substantially increased after growing all cultivars of the Phase 1 faba bean, barley, and most cultivars of chickpea and wheat, and decreased after two moderately resistant wheat cultivars and the fallow treatment. The biomass of the Phase 2 tolerant cultivar ranged from 5070 to 6780 kg/ha and the intolerant cultivar 1020 to 4740 kg/ha. There was a negative linear relationship between P. thornei population densities and biomass of the Phase 2 intolerant cultivar but not of the tolerant cultivar. Growers are at risk of financial loss because they are restricted in their choice of crops to reduce damaging population densities of P. thornei. The development of resistant and tolerant crop genotypes can maximize production in P. thornei-affected farming systems.
Highlights
Many wheat (Triticum aestivum) growers in Australia and internationally need to reduce damaging populations of the root-lesion nematode Pratylenchus thornei in their fields
Faba bean, and wheat grain yield there was a significant effect of cultivar (p = 0.039; < 0.001; < 0.001, respectively) but not of Experimental site (Supplementary Table S2)
For population densities of P. thornei at individual soil depth intervals 6 months after harvest of the Phase 1 winter crops, there was a significant interaction for soil depth x cultivars (p = 0.001); there was no significant effect of experimental site (p > 0.05)
Summary
Many wheat (Triticum aestivum) growers in Australia and internationally need to reduce damaging populations of the root-lesion nematode Pratylenchus thornei in their fields. This situation arises because the nematode has a broad host range and exhibits rapid, exponential population growth in-crop [1,2]. Pratylenchus thornei can cause up to 76% grain yield loss in intolerant wheat because plants suffer water and nutrient deficiency as this migratory nematode feeds and reproduces within roots [5,6]. The threshold of P. thornei population densities causing damage to intolerant wheat in the subtropical grain region of eastern Australia is estimated to be 2000 P. thornei/kg soil at any soil depth interval in the soil profile [10]
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