scholarly journals Aggressiveness of Mycosphaerella graminicola Isolates from Susceptible and Partially Resistant Wheat Cultivars

2002 ◽  
Vol 92 (6) ◽  
pp. 624-630 ◽  
Author(s):  
Christina Cowger ◽  
Christopher C. Mundt
Keyword(s):  
Partial Resistance ◽  
Growing Season ◽  
Mycosphaerella Graminicola ◽  
Wheat Cultivars ◽  
The Difference ◽  
Epidemic Development ◽  
Moderately Resistant ◽  
Collection Date ◽  
Field Plots ◽  
Pathogen Aggressiveness

The selective effect of quantitative host resistance on pathogen aggressiveness is poorly understood. Because two previous experiments with a small number of bread wheat cultivars and isolates of Mycosphaerella graminicola had indicated that more susceptible hosts selected for more aggressive isolates, we conducted a larger experiment to test that hypothesis. In each of 2 years, six cultivars differing in their levels of partial resistance were planted in field plots, and isolates were collected from each cultivar early and late in the growing season. The isolates were inoculated as populations bulked by cultivar of origin, field replicate, and collection date on seedlings of the same six cultivars in the greenhouse. The selective impact of a cultivar on aggressiveness was measured as the difference in aggressiveness between early and late isolates from that cultivar. Regression of those differences on disease severity in the field yielded significance values of 0.0531 and 0.0037 for the 2 years, with moderately resistant cultivars selecting for more aggressive isolates. In a related experiment, the protectant fungicide chlorothalonil was applied to plots of two susceptible cultivars to retard epidemic development. When tested in the greenhouse, isolates of M. graminicola from those plots were significantly more aggressive than isolates from the same cultivars unprotected by fungicide.

scholarly journals A Model of the Effect of Pseudothecia on Genetic Recombination and Epidemic Development in Populations of Mycosphaerella graminicola

2001 ◽  
Vol 91 (3) ◽  
pp. 240-248 ◽  
Author(s):  
L. Eriksen ◽  
M. W. Shaw ◽  
H. Østergård
Keyword(s):  
Genetic Recombination ◽  
Growing Season ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Considerable Proportion ◽  
Initial Population ◽  
Sexual Recombination ◽  
Epidemic Development ◽  
Rain Splash

It is generally agreed that ascospores are the origin of primary infections for the disease septoria tritici blotch of wheat caused by the fungus Mycosphaerella graminicola (anamorph Septoria tritici). The epidemic during the growing season was previously ascribed to the asexual pycni-diospores dispersed over short distances by rain splash, but recent observations suggest that the airborne ascospores also may play a role. As a consequence, the composition of the pathogen population over the growing season may change through genetic recombination. In an attempt to resolve the relative importance of the two spore types to the epidemic over the growing season, a model simulating disease caused by both types of spores was constructed and analyzed. The conclusion from the analysis of this model is that sexual recombination will affect the genetic composition of the population during a growing season. A considerable proportion of spores released at the end of the growing season may be sexual descendants of the initial population. However, ascospores are unlikely to affect the severity of the epidemic during the growing season. This is due to the much longer latent period for pseudothecia compared with pycnidia, resulting in ascospores being produced too late to influence the epidemic.

DEVELOPMENT AND YIELD OF CANADIAN WESTERN RED SPRING AND CANADA PRAIRIE SPRING WHEATS AS AFFECTED BY DELAYED SEEDING IN THE BROWN AND DARK BROWN SOIL ZONES OF SASKATCHEWAN

1990 ◽  
Vol 70 (3) ◽  
pp. 639-660 ◽  
Author(s):  
H. W. CUTFORTH ◽  
C. A. CAMPBELL ◽  
D. JUDIESCH ◽  
R. M. DePAUW ◽  
J. M. CLARKE ◽  
...  
Keyword(s):  
Protein Concentration ◽  
Grain Quality ◽  
Frost Damage ◽  
Wheat Cultivars ◽  
Brown Soil ◽  
Soil Zone ◽  
Seeding Date ◽  
Optimum Period ◽  
Early Fall ◽  
The Difference

Historically, research has identified the optimum period of seeding Canadian Western Red Spring (CWRS) wheat in the Brown soil zone to be between late April and mid-May, and approximately mid-May in the Dark Brown soil zone. The recent development and release of new spring wheat cultivars with significantly different genetic makeup (Canada Prairie Spring (CPS) wheats) prompted this study to determine if the established criteria were valid for them. Seeding date experiments involving one CWRS wheat (Neepawa) and three CPS wheats (HY320, HY355, HY912) were carried out at Swift Current (1984–1988) and at Regina and Scott (1985–1988). Although significant seeding date × cultivar interactions occurred for several of the characteristics measured (e.g., yield, protein concentration), no cultivar consistently responded differently than the others. However, the difference in days to reach maturity between the later maturing CPS cultivars and the CWRS cultivar, Neepawa, generally increased with delayed seeding making the CPS cultivars more susceptible to early fall frost damage which could decrease their yields and grain quality. Our results showed no reason to change recommendations for seeding dates in either soil zone, and both types of wheat can be treated similarly except that late seeding for CPS wheats should be avoided.Key words: Seeding date, grain yield, GDD, protein, wheat

ROOT-SURFACE MYCOFLORA OF SOYBEAN IN RELATION TO SOIL TEMPERATURE AND MOISTURE IN A FIELD ENVIRONMENT

1972 ◽  
Vol 52 (2) ◽  
pp. 199-208 ◽  
Author(s):  
K. C. IVARSON ◽  
A. R. MACK
Keyword(s):  
Soil Temperature ◽  
Relative Frequency ◽  
Incubation Temperature ◽  
Growing Season ◽  
Root Surface ◽  
Growing Seasons ◽  
Field Environment ◽  
Abundant Genus ◽  
Field Plots ◽  
Soil Temperature And Moisture

Studies were made on the root-surface fungi of soybean grown in field plots where various soil temperature and moisture environments had been maintained for five previous growing seasons. Washed-root segments were incubated on agar plates at temperatures corresponding to those of the field plots. Fusarium was the most abundant genus appearing on the plates. Species of Mucor, Trichoderma, Alternaria, Mortierella, Aspergillus, Corynespora, Rhizoctonia, Penicillium, Gliocladium, and sterile forms appeared fairly frequently. Statistical analysis of the data revealed that changes in soil and incubation temperature markedly affected the relative frequency of 12 genera, and age of plant significantly affected nine genera. Soil moisture influenced the frequency of only one genus. High soil and incubation temperature (28 C) encouraged greater root populations of Rhizoctonia early in the season, Trichoderma and Aspergillus throughout the growing season, and Fusarium late in the season. Low soil temperature conditions (12 C) favored growth of Pythium, Mortierella, Mucor, Alternaria, Cladosporium, throughout the growing season, and Corynespora and Cylindrocarpon, primarily during mid-season. Late in the season Gliocladium preferred the intermediate temperature of 20 C.

scholarly journals Reaction of winter wheat genotypes to infection by Mycosphaerella graminicola(Fuckel) Schroeter

2013 ◽  
Vol 55 (1) ◽  
pp. 233-246
Author(s):  
Ewa Mirzwa-Mróz ◽  
Czesław Zamorski
Keyword(s):  
Winter Wheat ◽  
Broad Spectrum ◽  
Mycosphaerella Graminicola ◽  
Wheat Breeding ◽  
Septoria Tritici ◽  
Wheat Cultivars ◽  
Breeding Lines ◽  
Wheat Genotypes ◽  
Winter Wheat Cultivars

The response of Polish winter wheat genotypes to <i>M.graminicola</i> (preliminary experiments and cultivar collections) was observed in different regions of Poland. Observations were carried out in 1995-1999. The winter wheat genotypes showed a broad spectrum of reaction to this pathogen. Between 1997 and 1999 the highest degree of infection on winter wheat breeding lines was noted in Kończewice. During this time no genotypes free from infection were observed (preliminary breeding experiments). Cultivars with no symptoms of <i>Septoria tritici</i> blotch (Leszczyńska Wczesna and Żelazna) were found among old genotypes in Słupia Wielka only in earlier experiments (1995-1996). In the years 1997-1999 the winter wheat cultivars were classified into groups on the basis of their response to the pathogen. The degree of infection for the majority cultivars was quite high.

scholarly journals Forest Soil Respirations are More Sensitive to Nighttime Temperature Change in Eastern China

2018 ◽  
Vol 47 (1) ◽  
pp. 249-254
Author(s):  
Zhaoyong SHI ◽  
Ke LI ◽  
Yongming WANG ◽  
Bede S. MICKAN ◽  
Weikang YUAN ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Temperature Change ◽  
Global Climate ◽  
Eastern China ◽  
Growing Season ◽  
Mean Value ◽  
Apparent Temperature ◽  
Effect Of Temperature ◽  
The Difference

Soil respiration is one of the main fluxes in the global carbon cycle. The effect of temperature on soil respiration is well understood. The response of soil respiration to temperature warming is called apparent temperature sensitivity (Q10) of soil respiration, which is an important parameter in modeling soil CO2 effluxes under global climate warming. The difference of Q10 between daytime and nighttime was hardly reported although attentions are attracted by the differences of temperature change and its effects on vegetation productivity. In this study, we investigated the Q10 of soil respiration in daytime and nighttime by modeling empirical functions based on the in situ measurement of soil respiration and temperature in temperate and subtropical forests of eastern China. Our results showed that the Q10 of soil respiration is higher in nighttime with the mean value of 2.74 and 2.35 than daytime with the average of 2.49 and 2.18 in all measured months and growing season, respectively. Moreover, the explanatory rate of soil temperature to soil respiration in nighttime is also higher than in daytime in each site in both all measured and growing seasons. The Q10 and explanatory rate of soil temperature to soil respiration in nighttime is 1.08 and 1.15 times in daytime in growing season. These findings indicate that soil respiration has a bigger sensitivity to temperature in nighttime than daytime. The change of soil temperature explains more variation of soil respiration in nighttime than daytime.

scholarly journals Response Patterns of Vegetation Phenology along Urban-Rural Gradients in Urban Areas of Different Sizes

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Xue Luo ◽  
Yuqing Zhang ◽  
Dongqi Sun
Keyword(s):  
Urban Areas ◽  
Growing Season ◽  
Liaoning Province ◽  
Vegetation Phenology ◽  
Coastal Cities ◽  
Nighttime Light Data ◽  
Urban Rural ◽  
Nighttime Light ◽  
Urban Size ◽  
The Difference

On the basis of MODIS Enhanced Vegetation Index time series data and multisource data, such as nighttime light data and China City Statistical Yearbook data, we investigated the differences in vegetation phenology along urban-rural gradients in urban areas of different sizes between coastal and inland cities in Liaoning Province, China. The results showed that the following: (1) the iterative extraction of urban built-up areas using the threshold method based on nighttime light data combined with the definition of urban built-up areas had high accuracy. (2) Additionally, we found that the start of the growing season (SOS) in Liaoning Province occurred between day 100 and day 180, while the end of the growing season (EOS) occurred between days 260 and 330. The difference in the SOS between coastal cities (i.e., Dalian, Yingkou, Panjin, Jinzhou, Huludao, and Dandong) and inland cities (i.e., Chaoyang, Fuxin, Tieling, Shenyang, Fushun, Liaoyang, Benxi, and Anshan) was 1.70 days. However, the difference in the EOS was more significant, i.e., the EOS in coastal cities occurred 4.47 days later than that in the inland cities. (3) In urban areas of different sizes, the ∆SOS and ∆EOS of inland cities had negative correlations with urban size. Specifically, when the urban size increased 10-fold, the ∆SOS and ∆EOS advanced by 10.03 and 5.71 days, respectively. In contrast, the ∆SOS and ∆EOS of coastal cities had positive and negative correlations with the urban size, respectively. Specifically, when urban size increased 10-fold, ∆SOS was delayed by 11.29 days while EOS was advanced by 8.83 days.

Resistance to Phytophthora medicaginis Hansen and Maxwell in wild Cicer species and its use in breeding root rot resistant chickpea (Cicer arietinum L.)

2008 ◽  
Vol 59 (4) ◽  
pp. 383 ◽  
Author(s):  
E. J. Knights ◽  
R. J. Southwell ◽  
M. W. Schwinghamer ◽  
S. Harden
Keyword(s):  
Field Experiment ◽  
Root Rot ◽  
Partial Resistance ◽  
The Other ◽  
Phytophthora Root Rot ◽  
Cicer Arietinum L ◽  
Cicer Species ◽  
Wild Cicer Species ◽  
Moderately Resistant ◽  
Chickpea Cultivars

Phytophthora root rot caused by Phytophthora medicaginis is a major disease of chickpea in Australia. Only partial resistance, derived from chickpea, is available in Australian cultivars. Five wild Cicer species were compared with chickpea cv. Jimbour (moderately resistant) in a field experiment. The proportions of accessions with significantly lower (P < 0.05) disease scores, where lower scores equate to higher resistance, were 9/9 for C. echinospermum, 9/21 for C. bijugum, 1/4 for C. judaicum, 1/29 for C. reticulatum, and 0/3 for C. pinnatifidum. The resistance of C. echinospermum (7/7 accessions) but not the other Cicer species was reproduced in a greenhouse test. Nine out of 30 chickpea × C. echinospermum-derived lines were as resistant as the C. echinospermum parents in a separate greenhouse experiment. C. echinospermum appears to be the best of the sources we examined for breeding chickpea cultivars resistant to P. medicaginis.

Effect of Crop Presence on Persistence of Atrazine, Metribuzin, and Clomazone in Surface Soil

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 698-703 ◽  
Author(s):  
Kent Gallaher ◽  
Thomas C. Mueller
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water Content ◽  
Half Life ◽  
Surface Soil ◽  
Growing Season ◽  
Soil Microbial Activity ◽  
Soil Microbial ◽  
Herbicide Concentration ◽  
The Difference

Atrazine, metribuzin, and clomazone half-lives averaged over treatments and seasons were approximately 27, 22, and 55 d, respectively. Clomazone dissipation was not affected by the presence or absence of a soybean crop. Atrazine and metribuzin dissipation was not affected by crops in 1992, but was more rapid in no-crop plots than in cropped plots in 1993. The difference may have been the result of higher soil water content with no-crop (a few weeds present) in 1993 than either corn or soybean. Lower soil moisture may have slowed soil microbial activity, thus suppressing atrazine and metribuzin degradation in the 1993 growing season. Few significant correlations were found between herbicide half-life or herbicide concentration and cocklebur growth, although one would expect these to be an index of activity.

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