Epidemics of stem rust and their effects on grain yield in the wheat WW15 and some of its derivatives

1981 ◽  
Vol 32 (5) ◽  
pp. 725 ◽  
Author(s):  
RG Rees ◽  
JR Syme

The progress of epidemics of Puccinia graminis tvitici strain 343-Anz-1,2,3,5,6 was examined in field plots of the wheat WW15, its hard-grained derivatives Condor, Oxley and Banks, the slow-rusting cv. Celebration and the fully resistant cv. Timgalen. Additional rust-free treatments were maintained to provide yield and quality comparisons. Severe epidemics developed in WW15, Condor and Oxley, and reduced grain yield in each cultivar by approximately 50 %. Epidemics in Celebration and Banks developed more slowly, and no significant loss in yield occurred. Reduced grain size accounted for most of the yield reduction in WW15, Condor and Oxley. Grain nitrogen concentration was higher in rusted Condor and Oxley than in rust-free treatments. WW15, Condor and Oxley possess little slow-rusting ability and the dependence on Condor and Oxley in the eastern wheat-belt of Australia should be decreased. Banks has effective stem rust resistance and offers potential as a replacement for Condor.

1990 ◽  
Vol 41 (6) ◽  
pp. 1057 ◽  
Author(s):  
R Dill-Macky ◽  
RG Rees ◽  
GJ Platz

The progress of epidemics of Puccinia graminis f. sp. tritici strain 343-Anz-1,2,3,5,6 was examined in field plots of the Australian barley cultivars Clipper, Corvette, Galleon, Grimmett, Prior and Schooner. The barley Purple Nudum, reported to possess seedling resistance to Puccinia graminis f. sp. tritici, and the susceptible wheat Oxley were also examined. Additional rust-free treatments were maintained to provide comparisons of grain yield and quality. Differences in the rate of epidemic development between cultivars were found. Moderate epidemics developed in Clipper, Schooner, Grimmett and Prior and no significant losses in yield were detected in Grimmett or Prior. Severe epidemics developed in Galleon, Corvette and Oxley and reduced grain yield by about half. Yield reductions were generally associated with reduced grain size and weight.


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.


2014 ◽  
Vol 163 (5) ◽  
pp. 353-363 ◽  
Author(s):  
Netsanet Hei ◽  
Hussein Ali Shimelis ◽  
Mark Laing ◽  
Belayneh Admassu

1976 ◽  
Vol 54 (19) ◽  
pp. 2204-2214 ◽  
Author(s):  
Mishael Oichoe Osoro ◽  
G. J. Green

Experiments were designed to show whether or not virulence genes reduce fitness and bring about stabilizing selection. The competitive abilities of seven related races of Puccinia graminis f. sp. tritici were studied on seedlings of three to five susceptible wheat varieties by growing mixtures of the races in greenhouses, growth cabinets, and field plots. In experiments in which simple races with few virulence genes were mixed with complex races with one, two, or three extra virulence genes, the complex races predominated after 4 to 10 generations in five of the six mixtures, and the simple race predominated in one mixture. A complex race predominated over simple races in the field experiment. It was concluded that virulence genes did not impair the fitness of the wheat stem rust races studied.In one race mixture studied in growth cabinets the complex race predominated at 25 °C, and the simple race, at 15 °C. Temperature did not differentially influence the competitive abilities of the races in three other mixtures.Incubation periods for all races were shorter at higher temperatures, but races C18(15B-1L) and C33(15B-1L) developed faster than races C9(15B-1L), C37(15), C38(15B-1L), C42(15), and C49(15) at all temperatures. In addition, races C18(15B-1L) and C33(15B-1L) produced more urediospores per pustule than races C9(15B-1L), C37(15), and C49(15). The differences in incubation period and spore production are considered to be the most important factors studied and they could cause the differences in aggressiveness of the seven races.


Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 674-678 ◽  
Author(s):  
R. Dill-Macky ◽  
A. P. Roelfs

The progress of epidemics of race QCCJ of Puccinia graminis f. sp. tritici was examined in field plots of the barley cultivars Robust, Excel, Stander, Azure, Stark, Larker, Bonanza, and Steptoe. In addition, a potential source of resistance (cv. Diamond), and a susceptible line (ND11075) were included. Rust-free treatments were maintained to provide comparisons of grain yield and quality. Barleys with Rpg1, which confers resistance to races of P. graminis f. sp. tritici other than Pgt-QCCJ, were generally more resistant than cultivars or lines that lacked this gene. However the severity of losses indicated that under high disease pressure the resistance conferred by Rpg1 would not be effective. Yield reductions of up to 29% were recorded and were generally associated with reduced grain size and weight. The continued presence of Pgt-QCCJ as a component of the P. graminis population in the United States, since it was first detected in 1989, indicates that Pgt-QCCJ remains a threat to commercial barley production.


Plant Disease ◽  
2006 ◽  
Vol 90 (1) ◽  
pp. 83-88 ◽  
Author(s):  
C. A. Clark ◽  
M. W. Hoy

During cycles of vegetative propagation, sweetpotato accumulates viruses that are thought to contribute to decline in yield and quality of cultivars, but the effects of specific viruses, many of which have been described only recently, are unknown. Field plots planted with graft-inoculated plants of a virus-tested (VT) mericlone of cv. Beauregard were used to assess the effects of three common potyviruses, Sweet potato feathery mottle virus (SPFMV), Sweet potato virus G (SPVG), and Ipomoea vein mosaic virus (IVMV); and a begomovirus, Sweet potato leaf curlvirus (SPLCV), compared with natural inoculum introduced by grafting plants from farmers' stock. Single infections with SPFMV, SPVG, or IVMV did not significantly affect yield, whereas mixed infections with SPFMV + SPVG or SPFMV + SPVG + IVMV resulted in mean yields 14% less than the VT controls. Infection with SPLCV resulted in mean yields 26% less than the VT controls, despite not causing symptoms on the foliage. However, grafting with farmers' plants infected with an unknown mixture of pathogens resulted in mean yields 31 to 44% less than the VT controls. Infection with potyviruses resulted in storage roots with tan periderm and infection with SPLCV induced darker periderm than the rosy VT controls. Infection with the viruses known to occur commonly in the United States did not reproduce the magnitude of yield reduction that has been observed with naturally infected plants.


2008 ◽  
Vol 53 (No. 9) ◽  
pp. 395-402 ◽  
Author(s):  
J. Potarzycki ◽  
W. Grzebisz

Malt barley production requires a technology increasing nitrogen use efficiency, because of a high sensitivity of barley total grain yield and quality parameters to external growth factors. In the conducted study an effect of two P fertilizers on the background of N application on total and technological grain yields were studied. The highest total grain yield was harvested on plots fertilized with 60 kg N/ha, irrespective of the P fertilizer type. However, the technological grain yield showed a high year-to-year variability; the highest was recorded in 2001 on the plot fertilized with 60 kg N/ha and the P-PAPR fertilizer. The N and S concentrations and N:S ratios in immature grains at harvest were used to evaluate both yield types. Nitrogen concentration in the final total yield allowed making yields prognosis with the highest probability. The maximum yields of technological malt barley were attainable provided that total S concentration in immature grains at harvest was above 0.23% and the N:S ratio was narrower than 8.0.


1978 ◽  
Vol 90 (2) ◽  
pp. 283-289
Author(s):  
B. F. Pain ◽  
S. J. Richardsonf ◽  
Rosemary J. Fulford

SummaryIn experiments over 3 years (1974–6) cow slurry in the range 0–112·5 t/ha and ammonium nitrate in the range 0–120 kg N/ha were applied to field plots factorially to test the effects on the yield and quality of spring barley grain.In 1974 slurry application markedly improved the grain yield (cv. Golden Promise) at each rate of inorganic N and increased grain size. Applying N fertilizer with more than 37·5 t slurry/ha reduced grain yield below the maximum. Grain with the highest crude protein content (15·1 %) was obtained from a combination of slurry and inorganic N. The residual effects of the slurry treatments gave satisfactory grain yields in 1975 without additional fertilizer.Grain yields (cvs Julia and Abacus) in other experiments carried out on a different soil type in 1975 and 1976 were approximately half those obtained in 1974, due in part to drought conditions. The pattern of the results was similar. Heaviest grain yields were harvested from plots receiving 70 t slurry/ha with no additional N.


1971 ◽  
Vol 11 (52) ◽  
pp. 550 ◽  
Author(s):  
BR Keed ◽  
NH White

The effects of Puccinia recondita and/or P. graminis var. tritici on the yield and quality of four Australian wheat cultivars were measured in 18 field experiments. Fortnightly applications of Dithane. S-31(R) provided almost rust-free plots for comparison with plots in which rust was allowed to develop. Leaf and stem rust intensities were assessed using the key diagram of Large and Griffin. Leaf rust caused a maximum loss of yield of 26 per cent on Mendos and 22 per cent on Gamut. Stem rust on 1156.238 caused losses of up to 49 per cent while both leaf and stem rusts on Gabo resulted in a maximum yield loss of 55 per cent. With all four cultivars, most of the yield reduction was caused by a reduction in the weight of individual grains, reflected in the losses in 1,000 grain weights. Infection by leaf or stem rust generally resulted in a reduction in bushel weight and protein content.


2001 ◽  
Vol 41 (4) ◽  
pp. 533 ◽  
Author(s):  
R. G. Flood ◽  
P. J. Martin

Plant nitrogen relationships were studied in 10 wheat cultivars sown at 3 sites (Horsham, Boort and Walpeup) in north-western Victoria by determining the nitrogen concentration and nitrogen content of plant components at anthesis and maturity. While the concentration of nitrogen varied in different plant components, whole plants at anthesis had a nitrogen concentration below the value required for maximum growth. The time to anthesis had an influence only on grain yield and grain nitrogen percentage at Horsham. Total assimilation of nitrogen at both anthesis and maturity was more strongly correlated to plant dry matter than plant nitrogen concentration. There was a significant negative correlation between grain nitrogen percentage and both nitrogen harvest index and harvest index. Grain yield was strongly correlated with total nitrogen accumulated at anthesis and more strongly correlated with total nitrogen accumulated at maturity. Grain yield was significantly correlated with nitrogen harvest index and more strongly correlated with harvest index. Grain yield was negatively correlated with grain nitrogen percentage. The negative association between grain nitrogen percentage and harvest index has important implications for the breeding of wheat with higher grain nitrogen percentage while maintaining or increasing grain yield. The results indicated that none of the measured parameters could be used for indirect selection aimed at improving grain nitrogen percentage.


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