Effect of wheat seed colour on the incidence and severity of red smudge and black point caused by Pyrenophora tritici-repentis

Non-Peer ReviewedPyrenophora tritici-repentis (Died.) Drechs. (anamorph Drechslera tritici-repentis (Died.) Shoemaker) causes red smudge, black point and dark smudge (Fernandez et al., 1998; 2001; Francl and Jordahl, 1993). This discoloration could result in downgrading due to low tolerance levels in the top grades (Canadian Grain Commission, 1994). Incorporation of disease resistance into all wheat classes would therefore be of economic benefit to producers. Fernandez et al. (2001) determined that cultivars in all four wheat quality classes tested were susceptible to P. tritici-repentis but that they differed in the predominant type and/or intensity of the discoloration and in incidence and severity of the infection. Some of the differences in the incidence and severity of the discoloration among cultivars appeared to be related to seed colour. Because there were differences also within classes not related to seed colour, the impact of seed colour per se on the development of kernel discoloration caused by P. tritici-repentis could not be accurately assessed. The objective of this study was to assess the incidence and severity of kernel discoloration caused by P. tritici-repentis in near-isogenic lines for seed coat colour so that genotypic effects could be separated from seed colour

Effect of leaf spot severity on yield and quality of durum wheat

Non-Peer ReviewedLeaf spots in wheat (Triticum aestivum L.) are important in Saskatchewan even under dry conditions (Fernandez et al., 2002). Durum wheat (T. turgidum L. var. durum) cultivars presently grown in western Canada are susceptible to leaf spots. The most common leaf spotting disease in durum wheat is tan spot [Pyrenophora tritici-repentis (Died.) Drechs. (anamorph Drechslera triticirepentis (Died.) Shoemaker)] Leaf spots are believed to cause reductions in yield and quality. The most widely used approach to measure the effect of leaf diseases on yield and its components has been the use of fungicides (Duczek and Jones-Flory, 1994; Eyal, 1972; Hosford and Busch, 1974; Rees and Platz, 1983). Inconsistent results with fungicide use in wheat were also reported (Bailey et al., 1992; Stover et al., 1996; Wang et al., 2002). In some cases, fungicide effects were not directly related to the occurrence of disease (Fehrmann et al., 1978; Wang et al., 2002), which makes them an unreliable tool to assess the effect of leaf spots on plant growth. To accurately quantify the negative effects of leaf spots on yield and quality, an approach other than disease control by fungicide application is necessary. The objective of this study was to evaluate the use of genotypes near-isogenic for leaf spot reaction to quantify the effect of leaf spots on grain yield and quality of durum wheat

Yield and protein response to N fertilization by different cultivars of spring and durum wheat

Non-Peer ReviewedA field study to determine whether there were differences in the response of CWAD and CWRS wheat to N fertilization was conducted in two soils of southwestern Saskatchewan for four years. Using regression techniques we were able to establish that both wheat classes had the same grain yield and protein concentration response to N availability, and that the differences in grain yield and protein concentration between classes observed in the study arose from differences in the response of the classes to available water. Differences in response to water availability among cultivars within each class were too small to be of practical significance. Recommendations for N fertilization of CWAD and CWRS wheats should be based on an N response common to both wheat classes, and on the ratio of the price of wheat to the cost of fertilizer N for each class

Advantages of using the Haun scale to determine cereal growth stage

Non-Peer Reviewe

Physiological characteristics of high-yielding and high-protein wheats in Canadian prairies: water use and water use efficiency

Non-Peer ReviewedThe moisture condition in the Canadian prairies is often not favourable to wheat growth especially during grain-filling stage (McCaig and Clarke, 1995) because of the limited precipitation, high temperature and high wind speed. Under this environment, new cultivars with both high yield and high protein concentration should have either higher evapotranspiration (ET) or higher water use efficiency (WUE), or both relative to old low- yielding cultivars. Few studies have been done to compare water use among wheat cultivars released at different periods of breeding (Slafer et al., 1993). Research conducted in Australia revealed that new high-yielding cultivars had higher WUE which was attributed to higher grain yield and higher harvest index, while ET did not change (Siddique et al., 1990a) or was even reduced (Siddique et al., 1990b). In a comparative study in the Canadian prairies, Cutforth et al. (1988) found that four wheat cultivars ( two common wheat and two durum cultivars), which were different significantly in yield, did not differ in ET. Similarly, McNeal et al. (1971) found no difference in ET among five wheat varieties, which were different in height. The objective of this study was to estimate the differences between old cultivars and new high-yielding and high-protein cultivars in ET and WUE in the Canadian prairies

Cultivar difference in within-spike N remobilization in CWRS wheat

Non-Peer ReviewedThe objective of the present study was to compare four new CWRS wheat cultivars with two older cultivars, Neepawa and Marquis, in terms of spike dry matter and nitrogen accumulation and within-spike partitioning. Results showed that new cultivars had significantly higher kernel mass and N content per spike than old cultivars, which were mainly attributed to their higher accumulation rates, instead of accumulation duration. N remobilization from glumes occurred during the linear phase of grain filling and new cultivars started remobilizing N earlier and had a higher rates than old cultivars. N remobilization of rachis started later and the rate was smaller than glumes. New cultivars had higher total N remobilization and maximum remobilization rate from rachis than old ones. It seems that cultivars with large sink size had a high rate of accumulation and were able to remobilize more carbohydrates and N into the grains before maturity. Cultivars with small sink size had both relatively low accumulation rate and remobilization rate. Although visual observations showed that Marquis and Neepawa had 1-3 days longer maturity than new cultivars, grain accumulation of carbohydrates and N was minimal during these days because of the severe water stress and/or heat stress

Do high-yield and high-protein wheat cultivars use more water?

Non-Peer ReviewedSome recently developed wheat cultivars have significantly increased yields, while maintaining or even increasing protein content, relative to earlier cultivars. Such cultivars, which meet the demands of the lucrative quality-conscious world markets, have made a substantial contribution to the value of wheat production in western Canada. In order to understand the physiological basis for these genetic improvements we are conducting a multiyear study. Results of this study could be used by breeders to select new cultivars more efficiently and by producers to improve their soil and crop management. In this report we describe cultivar differences in evapotranspiration (ET) and water use efficiency (WUE) from the experiment in 1998 and 1999 at Swift Current, Saskatchewan

Tillage system and cropping sequence effects on common root rot of barley in eastern Saskatchewan

Non-Peer ReviewedFusarium head blight (FHB) in barley has been spreading on the Canadian Prairies for the last decade. Fusarium spp. causing FHB can also cause crown/root rot of cereal crops. It is therefore of interest to determine the impact of agronomic practices on fungal populations associated with root rot of barley. From 1999 to 2001, 137 barley crops were sampled in eastern Saskatchewan for severity of subcrown internode discoloration and percent isolation of fungi. Cochliobolus sativus was the most commonly isolated fungus, whereas the most commonly isolated Fusarium spp. included the FHB pathogens F. avenaceum, F. culmorum and F. graminearum. Discoloration caused by C. sativus was favored by conventional-till, whereas Fusarium spp. increased in reduced tillage systems. Barley grown after a cereal-summerfallow (or summefallow-cereal) sequence under conventional- or minimum-till had increased levels of C. sativus. Fusarium spp. were most affected by the previously grown crop(s); they were more common in barley grown after a noncereal than a cereal, and after two noncereals, or a noncereal alternated with summerfallow. Previous glyphosate applications were associated with lower C. sativus, and higher Fusarium spp., levels in barley grown under minimum till. This suggests changes in fungal communities; however, the mechanism(s) responsible for these changes in fungal levels are not known. Increased infection of ground/underground tissue by FHB pathogens might contribute to its development in succeeding cereal crops, therefore measures aimed at reducing root/crown infections by Fusarium spp. might also help reduce FHB development

The effect of leaf spots on yield and quality of wheat in southern Saskatchewan

Non-Peer ReviewedAlthough leaf spots have been reported to have a negative effect on yield and quality, the magnitude of the effect of leaf spots on grain yield and quality of wheat cultivars grown on dryland in southern Saskatchewan is not known. Experiments were conducted at Swift Current (Brown soil) and Indian Head (Black soil) for three years to determine effects of leaf spots on grain yield, kernel weight, test weight and protein concentration of wheat. Two fungicides, Folicur 3.6F and Bravo 500 were applied at different growth stages in order to diversify the severity of leaf spots. Three common wheat (T. aestivum L.) cultivars - AC Domain, Laura and AC Elsa and three durum wheat (T. turgidum L. var durum) cultivars with different levels of leaf spot susceptibility were used in this study. The control of leaf spots by fungicides often did not cause an increase of yield, kernel weight, test weight or grain protein concentration in the drier Prairies where yield potential is relatively low. Fungicide treatments significantly increased yield in only two of six location-years (Folicur applied at head emergence in 1997 (0.07-0.13 t ha-1) (P < 0.05) and Folicur applied at flag emergence and/or head emergence in 1998 (0.41-0.47 t ha-1) (P < 0.001) at Indian Head. Fungicide applications significantly increased kernel weight in only three of six location-years (applications at flag leaf emergence at Swift Current (0.8-1.1 mg) (P < 0.05) and Indian Head (1.8-2.0 mg) (P < 0.001) in 1998 and at Indian Head in 1999 (10-1.1 mg) (P < 0.01). An increase of grain protein concentration was only found in treatments of Bravo applications at Indian Head in 1998 (0.3-0.7%) (P < 0.001). It seems that the control of leaf spots tended to have higher effect on yield and quality at Indian Head than Swift Current, it could be attributed to better controls of leaf spots at early milk stage (P < 0.001) and/or higher yield potential at Indian Head (P < 0.001). Although the cultivars used in this study have different leaf spot susceptibility (P < 0.001), there were no consistent cultivar differences in the effectiveness of the fungicides on control of leaf spots and on the yield, kernel weight and other quality characteristics. Leaf spots are a common and potentially severe foliar disease of wheat. Many studies have reported that leaf spots have a negative effect on grain yield (Eyal and Ziv, 1974; King, et al., 1983; McKendry and Henke, 1994), test weight (Milus, 1994) and milling quality (Mckendry et al., 1995), especially under environments favorable for the development of leaf spots or under intensive management such as irrigation (Duczek and Jones-Flory, 1994) and high N fertilizer rates (Howard, et al., 1994). In the past decade there has been an increase in the incidence of leaf spotting diseases of wheat in southern Saskatchewan, Canada. These are attributed mainly to Pyrenophora tritici-repentis (tan spot), Septoria nodorum and S. tritici (septoria leaf blotch complex) and all current spring wheat cultivars are susceptible to this disease complex - 333 - (Fernandez, et al., 1996; Fernandez, et al., 1998). Consequently there is increased pressure on producers to chemically control diseases that might affect yield and quality. The magnitude of the impact of leaf spots on grain yield and quality of wheat cultivars grown on dryland in this area, however, is not known. Research on these issues is therefore necessary to provide informed guidelines for use by producers. The objective of this study was to determine the effect of leaf spots on grain yield, kernel weight, test weight and protein concentration of spring common (T. aestivum L.) and durum (T. turgidum L. var durum) wheat in southern Saskatchewan

Durum – mechanisms of yield and grain protein improvements

Non-Peer Reviewe