Effect of wheat powdery mildew on grain nitrogen metabolism

Author(s):  
H. Y. Gao ◽  
J. S. Niu ◽  
W. Q. Liu ◽  
D. L. Zhang ◽  
S. P. Li

Abstract Glutamine synthetase (GS) and glutamate synthase (GOGAT) play a central role in plant nitrogen (N) metabolism. In order to study the effect of powdery mildew (Blumeria graminis f. sp. tritici, Bgt) on N metabolism, field experiments were carried out to evaluate GS and GOGAT activity, GS expression and grain protein content (GPC) in susceptible (Xi'nong 979) and resistant (Zhengmai 103) wheat cultivars under three treatments. The three treatments were no inoculation (CK), inoculated once with Bgt (MP) and inoculated nine times with Bgt (HP). For Xi'nong 979, the activities of GS and GOGAT in grains as well as GS activity in flag leaves increased at 10–15 days after anthesis (DAA), and decreased significantly at 15 or 20–30 DAA in HP and MP. However, GS activity in grains decreased from 20 DAA, which was later than that of flag leaves (15 DAA). At the same time, GS expression in grains was up-regulated at early stage, with GS1 at 10 DAA and GS2 at 15 DAA, followed by a continuous down-regulation. This result indicated that GS and GOGAT activity as well as GS expression were inhibited by powdery mildew, indicating that N metabolism in grains was inhibited at 20–30 DAA. The current study also found out that the yield of the susceptible cultivar decreased significantly, while its GPC increased obviously in HP. It was shown that the increase of GPC was not due to the enhancement of N metabolism, but due to the passive increase caused by yield reduction.

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 514 ◽  
Author(s):  
Mathew Dunn ◽  
Luke Gaynor

Powdery mildew—caused by the fungus Erisyphe diffusa (syn. Microsphaera diffusa)—was first observed in commercial soybean crops in southern New South Wales (NSW), Australia, in 2011. Its detection raised concerns that soybean production might be constrained if the severity of the disease reached the levels observed in northern Australia. Field experiments were conducted over four consecutive seasons to examine the response of three soybean cultivars—Djakal, SnowyA and the breeding line N005A-80—to two fungicides and two fungicide application regimes. The cultivar Djakal was identified as having a high level of resistance to powdery mildew. The severity of infection symptoms varied between seasons. The most severe symptoms were observed during the 2014–2015 season which resulted in the largest grain yield reduction of 20% for the cultivar SnowyA. All fungicide treatments provided a significant reduction in the severity of symptoms, with the split application of tebuconazole and both the single and split applications of tebuconazole + prothioconazole providing the most effective control of the disease. Few other grain yield effects were found, even when strong disease control was achieved. This was a suspected result of the consistent late-in-the-season onset of the disease. Few differences were observed among the treatments in terms of lodging severity, date of physiological maturity, or grain oil and protein concentrations. It was concluded that both fungicides provided effective control of powdery mildew. However, when disease pressure is low, application might not be warranted in southern NSW.


2007 ◽  
Vol 26 (2) ◽  
pp. 120-137
Author(s):  
A. J. Reinecke ◽  
S. A. Reinecke ◽  
M. S. Maboeta ◽  
J. P. Odendaal ◽  
R. Snyman

Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested. 


1999 ◽  
Vol 13 (3) ◽  
pp. 494-503 ◽  
Author(s):  
Leon S. Warren ◽  
Harold D. Coble

Field experiments were conducted in North Carolina from 1994 through 1998 to evaluate the effects of five weed management strategies and four corn (Zeamays)–peanut (Arachis hypogaea) rotation sequences on purple nutsedge (Cyperus rotundus) population development. Effects of these weed management programs on cotton (Gossypium hirsutum) and peanut production in following years were also investigated. Herbicide programs included a nontreated control, a carbamothioate preplant incorporated (PPI) combination treatment utilizing vernolate in peanut and butylate in corn, an early postemergence (EPOST) acetolactate synthase (ALS) inhibitor combination treatment utilizing imazapic in peanut and halosulfuron in corn, and EPOST treatments of imazapic and imazethapyr in both peanut and imidazolinone-resistant corn. Crop rotation sequences for the 3 yr included continuous corn (CCC), corn–peanut–corn (CPC), peanut–corn–peanut (PCP), and continuous peanut (PPP). The imazapic and ALS inhibitor combination treatments both provided excellent shoot and tuber control. After 3 yr, imazapic and the ALS inhibitor combination treatment reduced shoot and tuber population densities to less than 10% of the nontreated control. Imazethapyr provided variable but better control than the carbamothioate treatment with tuber densities (measured from 0 to 15 cm soil depth) and shoot densities increasing from 733 to 2,901 tubers/m3of soil and 16 to 43 shoots/m2, respectively, after 3 yr. Tuber densities increased in the nontreated control from 626 to 9,145 tubers/m3of soil and from 962 to 5,466 tubers/m3of soil in the carbamothioate treatment during this same period. Also, shoot densities increased in the nontreated control from 22 to 159 shoots/m2and from 8 to 92 shoots/m2in the carbamothioate treatment. There was a 31% peanut yield reduction from 1994 to 1996 when peanut was continuously planted or rotated to corn for only 1 yr. Herbicide carryover effects were not observed in cotton during 1997.


2017 ◽  
Vol 63 (No. 11) ◽  
pp. 498-504 ◽  
Author(s):  
Jiang Wenting ◽  
Liu Xiaohu ◽  
Qi Wen ◽  
Xu Xiaonan ◽  
Zhu Yucui

Accurate estimating of the balanced nutrition for maize is necessary for optimizing fertilizer management to prevent nutrient supply surplus or deficiency. Data from 300 field experiments in the Northeast China conducted between 2006 and 2011 were gathered to study the characteristics of maize yield, and using the QUEFTS model to estimate the balanced nutrition at different yield potential. The average grain yield was 10 427 kg/ha, and average internal efficiencies were 54.3, 251.5 and 78.2 kg grain per kg plant nitrogen (N), phosphorus (P) and potassium (K), respectively. With the harvest index values < 0.40 as outliers were excluded, the model simulated a linear-parabolic-plateau curve for the balanced N, P and K uptake when the initial yield target increased to the yield potential levels of 10 000 to 14 000 kg/ha. When the yield target reached approximately 60–70% of the yield potential, 16.7 kg N, 3.8 kg P, and 11.4 kg K were required to produce 1000 kg grain. The corresponding internal efficiencies were 60.0, 265.7 and 88.0 kg grain per kg plant N, P and K, respectively. These results contributed to improving nutrient use efficiency, and to demonstrate that the QUEFTS model could be a promising approach for estimating the balanced nutrition.


2001 ◽  
Vol 41 (8) ◽  
pp. 1179 ◽  
Author(s):  
S. R. Walker ◽  
G. R. Robinson ◽  
R. W. Medd

The competitive advantage of barley compared with wheat was quantified for suppressing seed production of Avena ludoviciana Durieu. (wild oats) andPhalaris paradoxa L. (paradoxa grass), and for improving herbicide effectiveness on these major winter grass weeds of the subtropical grain region of Australia. Eight field experiments were broadcast with weed seed before sowing wheat or barley, in which the emerged weeds were then treated with 4 herbicide doses (0, 25, 50, 100% of recommended rates). Yield reduction from untreated weeds was on average 4 times greater in wheat than in barley, with greater losses from A. ludoviciana than P. paradoxa. Barley did not affect weed emergence, but suppressed weed tiller density and, to a lesser extent, the number of weed seeds per tiller. Seed production was, on average, 4340 and 5105 seeds/m2 for A. ludoviciana and P. paradoxa, respectively, in untreated wheat compared with 555 and 50 seeds/m2 in untreated barley. Weed seed production following treatment with 25% herbicide rate in barley was similar or less than that after treatment with 100% herbicide rate in wheat. Overall, 25% herbicide rate was optimal for both conserving yield and minimising weed seed production in barley. For wheat, maximum yield was achieved with 50% herbicide but weed seed production was lowest with 100% herbicide rate. This indicates that weeds can be effectively controlled in barley with considerably less herbicide than required in wheat, highlighting the importance of including barley as a part of weed management strategies that aim to reduce herbicide inputs.


1988 ◽  
Vol 68 (2) ◽  
pp. 311-322 ◽  
Author(s):  
PATRICK M. McMULLAN ◽  
PETER B. E. McVETTY ◽  
AILEEN A. URQUHART

Dry matter and nitrogen (nitrate and reduced) accumulation and redistribution in four different spring wheat (Triticum aestivum L.) genotypes grown at field density were studied on a plant part and whole plant basis over the growing season for 2 yr. The four cultivars displayed significant differences in plant part and total plant dry matter, harvest index, nitrogen content, nitrogen concentration, nitrogen harvest index and nitrogen translocated values at most sample dates in both years. Grain yield was highly correlated with dry matter accumulation (r = 0.88**), while grain nitrogen content was highly correlated with plant nitrogen content (r = 0.95**). Nitrogen harvest index and plant nitrogen content were correlated at anthesis (r = 0.61**), while, as a consequence of this, the amount of nitrogen translocated was highly correlated with plant nitrogen content at anthesis (r = 0.87**). Nitrogen harvest index and harvest index were highly correlated (r = 0.83**), indicating that they may be related processes. Since plant dry matter and plant nitrogen content were not significantly correlated, it should be possible to select simultaneously for these traits to effect grain yield and grain nitrogen content increases on a per-plant basis. Further research will have to be done to determine how these changes will relate to grain nitrogen concentrations and grain yield per unit area.Key words: Wheat, dry matter, nitrogen, yield, protein, Triticum aestivum L.


1999 ◽  
Vol 50 (2) ◽  
pp. 137 ◽  
Author(s):  
A. Kamoshita ◽  
M. Cooper ◽  
R. C. Muchow ◽  
S. Fukai

The differences in grain nitrogen (N) concentration among 3 sorghum (Sorghum bicolor (L.) Moench) hybrids with similar grain yield were examined under N-limiting conditions in relation to the availability of assimilate and N to grain. Several manipulation treatments [N fertiliser application, lower leaves shading, thinning (reduced plant population), whole canopy shading, canopy opening, spikelet removal] were imposed to alter the relative N and assimilate availability to grain under full irrigation supply. Grain N concentration increased by either increased grain N availability or yield reduction while maintaining N uptake. Grain N concentration, however, did not decrease in the treatments where relative abundance of N compared with assimilate was intended to be reduced. The minimum levels of grain N concentration differed from 0.95% (ATx623/RTx430) to 1.14% (DK55plus) in these treatments. Regardless of the extent of variation in assimilate and N supply to grain, the ranking of hybrids on grain N concentration was consistent across the manipulation treatments. For the 3 hybrids examined, higher grain N concentration was associated with higher N uptake during grain filling and, to a lesser extent, with higher N mobilisation. Hybrids with larger grain N accumulation had a larger number of grains. There was no tradeoff between grain N concentration and yield, suggesting that grain protein concentration can be improved without sacrificing yield potential.


Weed Science ◽  
1991 ◽  
Vol 39 (3) ◽  
pp. 408-411 ◽  
Author(s):  
Billy R. Corbin ◽  
Robert E. Frans

Field experiments were conducted in 1986 and 1987 to evaluate the potential of growth regulators mepiquat chloride and chlormequat chloride as seed treatments to protect cotton from fluometuron injury. Fluometuron at two and three times the recommended use rate reduced cotton stand and height on Taloka and Convent silt loam soils both years. Cotton grown on a Sharkey silty clay soil was not injured by fluometuron. Mepiquat chloride and chlormequat chloride increased cotton stands on a Taloka silt loam soil when averaged over rates and years. In general, fluometuron injury to cotton was not reduced by treating seed with 1000 ppmw concentrations of chlormequat chloride or mepiquat chloride. Chlormequat chloride reduced chlorosis and necrosis of cotton treated with fluometuron, but neither growth regulator eliminated cotton injury or yield reduction caused by fluometuron at two or three times the recommended rates.


Weed Science ◽  
1993 ◽  
Vol 41 (2) ◽  
pp. 172-179 ◽  
Author(s):  
Jill Schroeder

Broadleaf weeds, including spurred anoda, emerge after direct-seeded chile peppers are thinned. Field experiments were conducted in 1989, 1990, and 1991 to determine the effect of spurred anoda density on green and red pepper yield, quality, and ease of hand harvest. Spurred anoda was established immediately after peppers were thinned at initial densities of 0, 3, 6, 12, 24, or 48 plants 9 m−1row. The 1991 experiment also evaluated the influence of delayed pepper thinning and concurrent spurred anoda establishment on the competitive effect of spurred anoda. Spurred anoda were beginning to flower at green harvest and senescing at red harvest regardless of planting date. Spurred anoda were taller and accumulated more biomass when planted at a pepper thinning stage of 10 cm compared to 20 cm. Spurred anoda that emerged after thinning peppers reduced yield and ease of harvest of green and red peppers but not the quality of green peppers. Yield reduction at the highest spurred anoda density was 31 to 49% and 12 to 27% when peppers were thinned at 10 or 20 cm, respectively. Yield reduction was smaller when peppers were thinned at 20 cm tall than 10 cm tall and appeared to be associated with reduced spurred anoda biomass. Time required to hand harvest 1 kg of green or red peppers increased as spurred anoda density increased when peppers were thinned at 10 cm.


Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 270-276 ◽  
Author(s):  
John D. Byrd ◽  
Alan C. York

Field experiments were conducted to determine the effects of tank-mixing fluometuron {N,N-dimethyl-N′-[3-(trifluoromethyl)phenyl] urea} or MSMA (monosodium salt of methylarsonic acid) with sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} or the butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanic acid} on cotton (Gossypium hirsutumL.) tolerance and large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA] control. Postemergence (over-the-top) application of 1.7 kg ai/ha of fluometuron reduced cotton lint yield 17 to 23% in three of four tests. No yield reduction resulted from postemergence application of 1.1 kg ae/ha of MSMA. Tank-mixing 0.1 or 0.2 kg ai/ha of sethoxydim or 0.1 or 0.2 kg ae/ha of fluazifop with fluometuron or MSMA did not alter the effect of fluometuron or MSMA on cotton yield. Tank mixtures of 1.1 to 2.2 kg/ha of fluometuron plus sethoxydim or fluazifop were antagonistic. No antagonism was observed when fluometuron was applied 3 days before or 6 h following sethoxydim or fluazifop application. Tank-mixing 1.1 or 2.2 kg/ha of MSMA with sethoxydim or fluazifop initially reduced control of large crabgrass. Antagonism was not observed at 4 weeks after tank-mix application of MSMA plus sethoxydim, and was observed in only one of three experiments 4 weeks following tank-mix application of MSMA plus fluazifop. When antagonism was observed with tank mixtures of fluazifop plus MSMA, sequential application of MSMA 1 to 7 days before application of fluazifop did not overcome the antagonism. No antagonism occurred when MSMA was applied 6 or more hours after fluazifop application.


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