Kabuli chickpea (<i>Cicer arietinum</i> L.) has two leaf types, the fern and unifoliate. Yield potential is limited for kabuli chickpea in Saskatchewan. It is limited by a short-season, a semi-arid environment, and end-of-season rainfall. Manipulating plant population, and choosing chickpea cultivars with the best leaf type for biomass production, radiation interception and yield for the early, middle, or late growth season, may increase chickpea yield. Therefore, the objectives of this study were: to (i) determine the relationship between leaf type and key growth parameters of six chickpea cultivars varying in leaf morphology at moderate and high plant population densities; (іі) to characterize the reaction of the fern and unifoliate leaf to altered canopy light environments. Different light environments were created by 50% defoliation at vegetative growth, first flower, and 50% shading from vegetative growth to first flower, as well as two light enrichment treatments initiated at the first flower and pod formation stages.<p> Fern leaf cultivars exhibited higher maximum light interception, seasonal cumulative intercepted radiation and a higher harvest index compared to unifoliate leaf cultivars. However, both leaf type canopies had less than 95% light interception for most of the season. The fern and unifoliate leaf type contributed to similar radiation use efficiency in three out of four location-years. In addition, fern leaf cultivars produced significantly higher seed yield than cultivars with unifoliate leaves.<p>Plant density influenced growth parameters. For example, the 45 plants m-2 treatment had a higher harvest index than the 85 plants m-2 treatment, in two location-years, while both population treatments were similar in the other two location-years. Yield of chickpea was increased by higher plant population in only one location-year, but was not significantly affected by plant population in the other location-years. The effect of canopy light environment manipulation on chickpea yield depended on the stages of plant development when they were applied. Defoliation at vegetative growth and first flower had no effect on yield. However, plants responded significantly to the 50% shade treatment; the crop growth rate, harvest index and yield were less in the shaded treatment compared to the control. Shading also increased plant height. Light enrichment treatments increased the yield. However, the degree of yield increase was greater when light enrichment occurred at first flower, than at the later stage of pod formation. These results highlighted the importance of the amount of irradiance during the flowering stage. It was concluded that chickpea breeders should select lines with fern leaves for improved radiation interception when breeding cultivars for semiarid short-season environments such as in Saskatchewan. Management and breeding practices should ensure that the crop can make efficient use of the solar radiation at flowering to maximize yield. Improvement at the canopy and subsequent yield level is yet to be made in Saskatchewan environments by increased light interception, increased growth before flowering, and increased and stable harvest index.

Kabuli chickpea (<i>Cicer arietinum</i> L.) has two leaf types, the fern and unifoliate. Yield potential is limited for kabuli chickpea in Saskatchewan. It is limited by a short-season, a semi-arid environment, and end-of-season rainfall. Manipulating plant population, and choosing chickpea cultivars with the best leaf type for biomass production, radiation interception and yield for the early, middle, or late growth season, may increase chickpea yield. Therefore, the objectives of this study were: to (i) determine the relationship between leaf type and key growth parameters of six chickpea cultivars varying in leaf morphology at moderate and high plant population densities; (іі) to characterize the reaction of the fern and unifoliate leaf to altered canopy light environments. Different light environments were created by 50% defoliation at vegetative growth, first flower, and 50% shading from vegetative growth to first flower, as well as two light enrichment treatments initiated at the first flower and pod formation stages.<p> Fern leaf cultivars exhibited higher maximum light interception, seasonal cumulative intercepted radiation and a higher harvest index compared to unifoliate leaf cultivars. However, both leaf type canopies had less than 95% light interception for most of the season. The fern and unifoliate leaf type contributed to similar radiation use efficiency in three out of four location-years. In addition, fern leaf cultivars produced significantly higher seed yield than cultivars with unifoliate leaves.<p>Plant density influenced growth parameters. For example, the 45 plants m-2 treatment had a higher harvest index than the 85 plants m-2 treatment, in two location-years, while both population treatments were similar in the other two location-years. Yield of chickpea was increased by higher plant population in only one location-year, but was not significantly affected by plant population in the other location-years. The effect of canopy light environment manipulation on chickpea yield depended on the stages of plant development when they were applied. Defoliation at vegetative growth and first flower had no effect on yield. However, plants responded significantly to the 50% shade treatment; the crop growth rate, harvest index and yield were less in the shaded treatment compared to the control. Shading also increased plant height. Light enrichment treatments increased the yield. However, the degree of yield increase was greater when light enrichment occurred at first flower, than at the later stage of pod formation. These results highlighted the importance of the amount of irradiance during the flowering stage. It was concluded that chickpea breeders should select lines with fern leaves for improved radiation interception when breeding cultivars for semiarid short-season environments such as in Saskatchewan. Management and breeding practices should ensure that the crop can make efficient use of the solar radiation at flowering to maximize yield. Improvement at the canopy and subsequent yield level is yet to be made in Saskatchewan environments by increased light interception, increased growth before flowering, and increased and stable harvest index.

Field pea is an important annual crop due to its contribution to soil fertility and other rotational benefits. However, weeds and ascochyta blight limit pea yield, particularly in organic systems. Leafed and semi-leafless pea types differ in lodging resistance, and may affect weeds and disease through differences in canopy light penetration and air flow. Mixtures of the two leaf types may improve weed and disease suppression and yield compared with monocultures of the same cultivars. To test this hypothesis, replicated field experiments were conducted under organic and conventional management in Saskatoon and Vonda, SK, in 2011 and 2012. Mixtures of a leafed and semi-leafless cultivar, CDC Sonata and CDC Dakota, were sown in ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 leafed to semi-leafless pea, at target seeding rates of 88 and 132 plants m-2. Conventionally managed plots were inoculated with ascochyta blight-infested pea straw and received overhead irrigation to encourage disease. Mixtures of 50% or more semi-leafless pea adopted the greater lodging resistance and weed suppression of the semi-leafless cultivar. Mixtures comprised of 25% leafed and 75% semi-leafless pea increased both seed and biomass yield compared with either cultivar grown alone. Yield enhancement was attributed to the leafed cultivar, whose seed yield was 76% higher in mixture than expected based on monoculture yield. Ascochyta blight epidemics were of moderate severity, and leafed and semi-leafless monocultures reached 36 and 43% necrosis in 2011, and 33 and 38% necrosis in 2012, respectively. The disease reaction of mixtures fell between the two component cultivars. At disease onset in 2012, lower light interception and shorter moisture durations coincided with the lower ascochyta blight severity of leafed monocultures. In 2011 and the later phase of the 2012 epidemic, disease severity was negatively associated with vine length, and positively associated with number of nodes and tissue senescence. Despite the advantages of leafed and semi-leafless pea mixtures, the limited selection of leafed cultivars impedes adoption of this technique by growers. For pea breeders, developing mixtures of pea lines isogenic for leaf type may increase yield compared with single cultivars.

Chickpea (Cicer arietinum L.) production on the semi-arid Canadian Prairies is challenging due to a short growing season and low and variable moisture. The current recommended chickpea population density of 44 plants m-2 is based on preliminary studies and a narrow range of 20 to 50 plants m-2. The aims of this study were to i) determine optimum population density of varying chickpea canopy types, i.e., leaf type and growth habit, by investigating seed yield responses at 30 to 85 plants m-2 and ii) identify desirable parental traits for breeding programs by assessing growth and yield parameter responses to varying leaf types and growth habits at a range of population densities. Field experiments were conducted from 2002 to 2005. Canopy measurements and calculated variables included light interception, biomass, growth rate, seed yield, harvest index, ascochyta blight severity and radiation- and water use efficiencies. The plant density which produced the highest seed yield when averaged over years for each location for each treatment revealed that a plant density of at least 55 plants m-2 produced a 23% to 49% seed yield increase above that of the currently recommended plant density. This indicates that a higher seed yield average over the long term in spite of periodic low seed yield episodes will be more profitable to producers. Increasing plant density increased lowest pod height significantly in all except one location-year but did not explicitly increase ascochyta blight severity or decrease individual seed size. This suggests that increasing the recommended chickpea plant density on the Canadian Prairies will increase seed yield but would neither negatively impact individual seed size nor ascochyta blight severity, especially, when combined with good agronomic practices. Fern-leaved cultivars had significantly higher maximum intercepted light (62 to 91%), seed yield (136 to 369 g m-2), harvest index (0.33 to 0.53), yield-based water use efficiency (0.56 to 1.06 g m-2 mm-1) and lower ascochyta blight severity (3 to 27%) than the unifoliate cultivars in all location-years. The fern-leaved cultivars also tended to show significantly higher cumulative intercepted radiation (221 to 419 MJ m-2) and biomass (306 to 824 g m-2) but leaf type showed no consistent effect on radiation use efficiency. Cultivars with bushy growth habit generally performed better regarding maximum intercepted light (62 to 90%), cumulative intercepted radiation (233 to 421 MJ m-2), biomass (314 to 854 MJ m-2), seed yield (120 to 370 g m-2), harvest index (0.37 to 0.50), yield-based water use efficiency (0.56 to 1.06 g m-2 mm-1) and ascochyta blight severity (7 to 36%) than the erect cultivars. The overall performance of the spreading cultivar was generally intermediate between the bushy and erect cultivars except for ascochyta blight severity where the spreading cultivar exhibited significantly lower disease severity (3 to 36%). Radiation use efficiency was generally not influenced by growth habit. Increasing plant population density generally increased intercepted light, biomass and cumulative intercepted radiation on each sampling day after seeding resulting in a general increase in seed yield. Harvest index, however, remained constant and ascochyta blight severity was generally stable but radiation use efficiency decreased with increasing population density. Chickpea cultivars with fern leaves and bushy growth habit at higher than currently recommended population densities would best utilize the limited resources of the short-season Canadian prairie environment to maximize and stabilize seed yield.

Chickpea (Cicer arietinum L.) production on the semi-arid Canadian Prairies is challenging due to a short growing season and low and variable moisture. The current recommended chickpea population density of 44 plants m-2 is based on preliminary studies and a narrow range of 20 to 50 plants m-2. The aims of this study were to i) determine optimum population density of varying chickpea canopy types, i.e., leaf type and growth habit, by investigating seed yield responses at 30 to 85 plants m-2 and ii) identify desirable parental traits for breeding programs by assessing growth and yield parameter responses to varying leaf types and growth habits at a range of population densities. Field experiments were conducted from 2002 to 2005. Canopy measurements and calculated variables included light interception, biomass, growth rate, seed yield, harvest index, ascochyta blight severity and radiation- and water use efficiencies. The plant density which produced the highest seed yield when averaged over years for each location for each treatment revealed that a plant density of at least 55 plants m-2 produced a 23% to 49% seed yield increase above that of the currently recommended plant density. This indicates that a higher seed yield average over the long term in spite of periodic low seed yield episodes will be more profitable to producers. Increasing plant density increased lowest pod height significantly in all except one location-year but did not explicitly increase ascochyta blight severity or decrease individual seed size. This suggests that increasing the recommended chickpea plant density on the Canadian Prairies will increase seed yield but would neither negatively impact individual seed size nor ascochyta blight severity, especially, when combined with good agronomic practices. Fern-leaved cultivars had significantly higher maximum intercepted light (62 to 91%), seed yield (136 to 369 g m-2), harvest index (0.33 to 0.53), yield-based water use efficiency (0.56 to 1.06 g m-2 mm-1) and lower ascochyta blight severity (3 to 27%) than the unifoliate cultivars in all location-years. The fern-leaved cultivars also tended to show significantly higher cumulative intercepted radiation (221 to 419 MJ m-2) and biomass (306 to 824 g m-2) but leaf type showed no consistent effect on radiation use efficiency. Cultivars with bushy growth habit generally performed better regarding maximum intercepted light (62 to 90%), cumulative intercepted radiation (233 to 421 MJ m-2), biomass (314 to 854 MJ m-2), seed yield (120 to 370 g m-2), harvest index (0.37 to 0.50), yield-based water use efficiency (0.56 to 1.06 g m-2 mm-1) and ascochyta blight severity (7 to 36%) than the erect cultivars. The overall performance of the spreading cultivar was generally intermediate between the bushy and erect cultivars except for ascochyta blight severity where the spreading cultivar exhibited significantly lower disease severity (3 to 36%). Radiation use efficiency was generally not influenced by growth habit. Increasing plant population density generally increased intercepted light, biomass and cumulative intercepted radiation on each sampling day after seeding resulting in a general increase in seed yield. Harvest index, however, remained constant and ascochyta blight severity was generally stable but radiation use efficiency decreased with increasing population density. Chickpea cultivars with fern leaves and bushy growth habit at higher than currently recommended population densities would best utilize the limited resources of the short-season Canadian prairie environment to maximize and stabilize seed yield.