Xu M.L.,Chinese Academy of Agricultural Sciences |
Yang J.G.,Chinese Academy of Agricultural Sciences |
Wang F.L.,Chinese Academy of Agricultural Sciences |
Wu J.X.,Peanut Research Institute of Shandong Province |
Chi Y.C.,Peanut Research Institute of Shandong Province
Plant Disease | Year: 2015
During late June and early July 2013 and 2014, peanut (Arachis hypogaea) plants with root rot symptoms were collected from Rizhao City, Shandong Province, China. Symptoms were observed at the seedling stage, and caused stem base and root discoloration. The affected plants were stunted, with chlorotic leaf, reduced growth, and/or sudden wilting. As the disease progressed, the infected tissues became brown and began to rot. White, cotton-like hyphae were observed on the symptomatic tissues. The rotted cortical tissues collapsed easily when pushed with a finger. Eventually, the affected plants collapsed and died. To isolate the causal organism, roots and stems were cut into 0.3- to 0.5-cm sections, surface disinfected with 70% ethanol solution (v/v) for 20 s, soaked in 0.1% mercuric chloride solution for 50 s, rinsed with sterilized water three times, dried, placed on Czapek Dox agar supplemented with 100 μg/ml of chloramphenicol, and incubated at 30°C for 3 to 5 days. The fungal colonies associated with the plated tissues were white and initially produced abundant aerial growth, from which black sporangia emerged. The hyphae were rarely septate and the sporangiophores, which developed from basal rhizoids, were usually straight, smooth-walled, 200 to 1000 μm long, with simple or several branches that were 5 to 20 μm in diameter and bore apical sporangia. The sporangia were globose or subglobose, and were 60 to 200 μm in diameter. The sporangiospores were unequal, globose or subglobose, and were 4 to 12 μm in diameter. The rhizoids and stolons were dark brown with several branches. Total genomic DNA was extracted from the mycelia using an EasyPure Genomic DNA Kit (TransGEN, Beijing, China). The rDNA-ITS region was amplified using PCR and the universal fungal primers, ITS1 and ITS4 (White 1990). The purified products were separately sequenced in both directions using the same primer pair. The sequences (GenBank Accession No. KP771803) obtained were 100% similar to the ITS sequence fromRhizopus oryzae isolates. This, together with the morphological characteristics (Watanabe 2002;Dolatabadi et al. 2014) described above, suggested the microorganism isolated from the diseased tissues was Rhizopus arrhizus (syn. R. oryzae). Koch’s postulates were completed in the laboratory by inoculating peanuts. Forty ‘Huayu 20’ peanut seeds were placed in a 500-ml, sterile pot with 300 g autoclaved soil. Two weeks after seedling emergence, the roots of 20 peanut plants were wounded with a needle and inoculated with 5 ml sporangiospores suspension (106/ml). The same number of peanut plants were similarly wounded and inoculated with 5 ml sterile distilled water to serve as controls. The peanut plants were arranged in a randomized complete block design, and grown at 30°C with a 12-h photoperiod. After 7 days, disease symptoms similar to those observed in the field appeared on all inoculated plants, but not on the noninoculated plants. The tests were repeated three times in the greenhouse. Koch’s postulates were satisfied after reisolating the R. arrhizus (as R. oryzae) from inoculated peanuts using the same method. To our knowledge, this is the first report of R. arrhizus (as R. oryzae) causing root rot in peanut plants in China. © 2015 American Phytopathological Society. All rights reserved.
Zhang Z.M.,Peanut Research Institute of Shandong province |
Zhang Z.M.,Shandong Agricultural University |
Song W.W.,Peanut Research Institute of Shandong province |
Song W.W.,Shandong Agricultural University |
And 10 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013
Used a pool culture under rainproof, the effect of non-sufficient irrigation in different growth stages on leaf membrane lipid peroxidation, osmoregulation substances content and the protective enzyme activity of different peanut varieties were studied. The aim was to reveal the response mechanism of different peanut varieties to non-sufficient irrigation in different growth stages. The result showed that leaf protective enzyme activities, osmoregulation substances and malondialdehyde content reduced in different degrees after irrigation in seedling and flowering-pegging stages. Their activities increased with the growth of peanut and the reduction of soil moisture, but the increasing ranges were different because of peanut varieties, and kinds of protective enzymes or osmoregulation substances. The increasing range of leaf SOD, CAT, the content of soluble sugars, soluble proteins, free amino acids and proline of two varieties were larger in flowering-pegging stage, which is the most sensitive stage to water stress, than other stages. And the increasing range of leaf SOD, CAT, soluble proteins, and free amino acids content of Huayu 27 were larger than those of Huayu20. The protective enzymes activity and osmoregulation substances content were not reduced after irrigation in pod setting stage. The activity of protective enzymes and the osmoregulation substances content and MDA had no significantly difference between two varieties with irrigation in the whole growth stage and seedling stage. The activity of protective enzymes and the osmoregulation substances content and MDA in water stress under whole growth stage were increased significantly compared with irrigation treatment. The changing ranges of Huayu 27 were larger than those of Huayu22. The activity of POD was weakly affected by irrigation stage. SOD and CAT were the mostly protective enzymes of peanut to adapt to soil water stress.
Sun T.,Shandong Agricultural University |
Zhang Z.,Peanut Research Institute of Shandong Province |
Ning T.,Shandong Agricultural University |
Mi Q.,Shandong Agricultural University |
And 3 more authors.
Plant, Soil and Environment | Year: 2015
A two-year field experiment was conducted to investigate the effects of colored polyethylene (PE) films on weed control, soil temperature and moisture, and pod yield of peanut. By setting a clear PE film (CF) as control, three colored PE films were studied: black-clear-black color-matching film (BCF), silver grey film (SF) and black film (BF). The colored PE films were effective in controlling weeds compared with CF, while BF had the optimal weed control effect. Compared with CF, the colored PE films were not sensitive to air temperature, and had smaller daily temperature variations. Soil moisture at 0–40 cm depth was higher mulched with the colored PE films than those with CF, and the highest moisture occurred in BF. Peanut covered colored PE films remained higher chlorophyll content and net photosynthetic rate in the late growth stage. Compared with CF, the pod yields with BCF, SF and BF were significantly increased by 12, 7, and 5% in 2012, and 14, 10, and 5% in 2013, respectively. The treatments of SF and BCF get higher yields in 2012 and in 2013. Accordingly, SF and BCF may be better field-management options for weed control and high yield in peanut field. © 2015, Institute of Agricultural and Food Information. All rights reserved.