Abstract
The distribution frequency of pathogenic fungi associated with root and crown rot of winter wheat (Triticum aestivum) from 104 fields in the North China Plain was determined during the period from 2013 to 2016. The four most important species identified were Bipolaris sorokiniana (24.0% from roots; 33.7% from stems), Fusarium pseudograminearum (14.9% from roots; 27.8% from stems), Rhizoctonia cerealis (1.7% from roots; 4.4% from stems), and Gaeumannomyces graminis var. tritici (9.8% from roots; 4.4% from stems). We observed that the recovered species varied with the agronomic zone. Fusarium pseudograminearum was predominant in regions 1 and 3, whereas F. graminearum, F. acuminatum, and R. cerealis were predominant in regions 2 and 4. The incidence of F. pseudograminearum and R. cerealis was significantly different between regions 1 and 4, while no significant association was found in the distribution of the other species and the agronomic zones. A negative correlation between the frequency of occurrence of F. pseudograminearum and mean annual precipitation during 2013–2016 (r = −0.71; P < 0.01) in the North China Plain and a positive correlation between the mean annual precipitation during 2013–2016 and the frequency of occurrence of F. asiaticum (r = 0.74; P < 0.01) were observed. Several Fusarium species were also found with low frequencies of ~2.1%−3.4 % (F. graminearum, F. acuminatum, and F. sinensis) and ~0.1%−1.3% (F. equiseti, F. oxysporum, F. proliferatum, F. culmorum, F. avenaceum, and F. asiaticum). In more than 93% of the fields, from the root and crown tissues of wheat, two or more root and crown rot species were isolated. The coexistence of Fusarium spp. and B. sorokiniana in one field (65.4%) or in individual plants (11.6%) was more common than for the other species combinations. Moreover, this is the first report on the association between F. sinensis and root and crown rot of wheat. Our results would be useful in the framing guidelines for the management of root and crown rot fungi in wheat in different agronomic zones of the North China Plain.
Highlights
China has one of the largest wheat-planting areas (21 million ha), worldwide, and produces 87.7867 million tons of wheat, which is 19% of the total world production (National Statistical Year book 2014)
Bipolaris sorokiniana (Bs). sorokiniana, and G. graminis var. tritici were the predominant pathogens recovered from the wheat root samples, with isolation frequencies of 14.9, 24, and 9.8% (Nroots = 1,612 plants), respectively, whereas F. graminearum, F. acuminatum, F. sinensis, F. equiseti, F. oxysporum, F. proliferatum, F. culmorum, F. avenaceum, and R. cerealis were the minor pathogens identified, with isolation frequencies of 2.4, 2.7, 3.4, 0.6, 0.9, 0.7, 0.1, 0.1, and 1.7%, respectively (Table 2)
F. pseudograminearum and B. sorokiniana were the major species found in the stems in these areas, with isolation frequencies of 27.8 and 33.7% (Nstems = 1831 plants), respectively, and F. graminearum, F. asiaticum, F. acuminatum, F. sinensis, F. equiseti, F. oxysporum, F. proliferatum, R. cerealis, and G. graminis var. tritici were the minor pathogens with isolation frequencies of 2.1, 0.4, 2.6, 3.2, 1.3, 0.5, 0.7, 4.4, and 4.4%, respectively (Table 3)
Summary
China has one of the largest wheat-planting areas (21 million ha), worldwide, and produces 87.7867 million tons of wheat, which is 19% of the total world production (National Statistical Year book 2014). The North China Plain is the major wheat producing area, accounting for 72% of the China’s output. The climatic conditions vary across the Yellow River, the Yangtze River, and the Haihe River of Henan in the North China Plain, the average annual temperature rang from 13 to 16◦C, the rainfall from 300 to 1,100 mm, and the elevation from 23.2 to 2413.8 m. As the incidence of root and crown rot diseases of wheat are reported to be different in the four agronomic zones and several pathogenic fungi can cause the same disease in wheat, the distribution of predominant species associated with root and crown rot and their relationship with the climate variables have been important issues for research in the North China Plain
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