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

Physiological characteristics of recent Canada western red spring wheat cultivars: nitrogen uptake and remobilization

Non-Peer ReviewedGenetic yield gains have been difficult to achieve within the CWRS wheat class because of stringent quality requirements, and a growing-season environment of low precipitation and high temperatures. Understanding the physiological basis of yield gains may provide breeders with better insight as to the selection of parents, or provide screening tools to identify desirable genotypes. The objective of the present study was to compare four new CWRS wheat cultivars, which averaged higher yields than Neepawa in three years of multi-location testing within registration trials, both as a group and individually while maintaining or even increasing protein content, with two older cultivars, Neepawa and Marquis, in terms of N uptake and N remobilization. Results indicated that new cultivars had higher N uptake and/or higher N remobilization than old cultivars. Low tissue N concentration at maturity could be a criterion for selecting high-yielding and high-protein cultivars.Grain protein concentration (GPC) is an important trait of major interest in breeding of bread wheat (T. aestivum L.), because it determines both baking and nutritional properties. Breeding for both high yield and high GPC is very difficult as a negative relationship between yield and GPC was found by many studies (Simmonds 1995; McNeal, et al., 1972; Whitehouse, 1973; Bhatia, 1975; Costa and Kronstad, 1994). Simmonds (1996), therefore, concluded that high yield and high GPC were unattainable simultaneously. However, Kibite and Evans (1984) indicated that the negative relationship between yield and GPC was not primarily driven by genetic factors, but mainly by environmental factors. Cox et al. (1985) found that negative correlations between yield and GPC for some wheat lines were low, although significant, which indicated that simultaneous increase in yield and GPC could be achieved by selection. This is supported by some studies (Davis et al., 1961; Terman et al. 1969; Johnson, 1978; McKendry et al. 1995). Jenner et al. (1991) indicated there is no fundamental conflict on physiological grounds in selecting cultivars for high carbohydrate yield at acceptable, even high, levels of GPC. GPC is determined by plant total nitrogen (N) uptake and N remobilization to the grain. Many studies found genetic differences in N uptake (Löffler, et al. 1985; Van Sanford and MacKown, 1986; Le et al. 2000; Desai and Bhatia, 1978; McKendry, et al. 1995), while Oscarson et al. (1995) did not find any major differences in NO3 uptake capacity among wheat grown hydroponically. A positive correlation between N uptake and GPC was found by Beninati and Busch (1992) and McKendry et al. (1995), but not by others (McNeal et al. 1966; Johnson et al. 1967; Desai and Bhatia 1978). Cultivar difference in N remobilization was also found by some authors (Seth et al. 1960; Johnson et al. 1968; Van Sanford and MacKown, 1987). However, the relationship between plant N metabolism and GPC was not clear. Some reported that N partitioning was associated with GPC (Johnson et al. 1968; Cox et al. 1986; McKendry et al. 1995), but others (McNeal et al. 1972; Woodruff 1972; Van Sanford and MacKown 1987; May et al. 1991) did not support this. Nitrogen harvest index was (grain N at maturity/maximum N uptake, %) used as a selection criterion by some authors (Desai and Bhatia 1978; Cregan and Berkum 1984; Löffler et al. 1985; Jenner et al. 1991; McKendry et al. 1995). Borghi et al. (1987) suggested that both higher biomass yield and efficiency of N remobilization are important traits to overcome the negative relationship between grain yield and GPC. Some studies suggested to use tissue N (Rostami and Giriaei 1998; Rostami and O'Brien 1996; Sylvester-Bradley 1990) or tissue protein concentrations (Noaman and Taylor 1990; Noaman et al. 1990) as selection criteria for increasing GPC because they were positively correlated with GPC. However, Jenner et al. (1991) indicated that from a physiological point of view, there is little logic in using grain protein percentage as a selection criterion. Delzer et al. (1995) also pointed that selection for grain protein only is questionable because the higher GPC is often associated with lower grain yield. Although there are not short of studies on N mechanisms, there are lack of consistencies in the results. Clarke et al. (1990) indicated that unless greater variation in N utilization parameters among cultivars can be demonstrated, there seems to be little justification for selection for parameters other than grain yield and protein concentration. Some recently developed bread wheat cultivars in western Canada have significantly increased yields, while maintaining or increasing percent protein content, relative to earlier cultivars (Wang et al. 2002). These cultivars can be used to study the physiological basis for these genetic improvements in N utilization. A better understanding of these improvements may allow breeders to design more efficient screening methods to develop future high yield and high GPC cultivars. This information may also assist agronomists and producers design soil and crop management practices that will permit full expression of these improved traits. The objective of this study was to estimate the characteristics of these new cultivars in N utilization in comparison with older cultivars and to identify potential criteria for selection of high yield and high GPC cultivars in the western Canadian semiarid prairie

What kind of wheat cultivar should I seed?

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Genotype difference in kernel discolorations in CWRS and CWAD wheats

Non-Peer ReviewedKernel discolorations of wheat, such as black point (including smudge and penetrated smudge), red smudge and Fusarium-damaged kernel (FDK), are important downgrading factors in western Canada. This study was undertaken to determine cultivar differences in incidences of these kernel discolorations and their downgrading effects in CWRS and CWAD wheats. Grain samples were taken at maturity from six CWRS and four CWAD cultivars in a four-year (1997-2000) field study at six sites: one in the Grey soil zone, two in the Brown soil zone and three in the Black soil zone in western Canada. For CWRS cultivars, Garnet tended to have lower incidences in black point, smudge and FDK and resulted in the least downgrading compared with other CWRS cultivars. For CWAD cultivars, Kyle tended to have lower incidence of black point, Plenty had less smudge caused downgrading effects, DT 369 had lower penetrated smudge incidence, but higher red smudge incidence, and Plenty tended to have severer FDK-caused downgrading effects compared with other CWAD cultivars. CWAD class had higher frequency of downgrading than CWRS class and it usually had higher incidences of all kernel discolorations (black point, smudge, penetrated smudge, red smudge and FDK) and greater downgrading effects than CWRS class

High-yield, high-protein CWRS wheat cultivars

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