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A field study was conducted to determine if high seeding rates were economically beneficial for irrigated corn silage production in southern Alberta. On average, 84% of seeds produced a plant, with 12% higher plant establishment in narrow (38 cm) than wide (76 cm) rows. Row spacing did not significantly affect yield, but maximum profitability was attained with a lower seeding rate for narrow rows. Whole-plant dry matter yields and net income were increased by 13% when seeding rates were increased from 64 000 to 74 000 seeds ha-1, but were not significantly affected by seeding rates from 74 000 to 114 000 seeds ha-1. The ideal seeding rate within this range may vary due to site specific conditions. Forage quality was unaffected by seeding rate. Key words: Corn, Zea mays L., irrigated silage production, quality, plant population, row spacing

Chickpea (Cicer arietinum L.) has two kinds of leaf types, the fern and unifoliate. The best leaf type to use for biomass production and yield in the short growing season of the Northern Great Plains, which has a semiarid environment with end of season rainfall, is not yet known. The objectives of this research were to determine the relationships between leaf type and crop growth rate, maximum above-ground biomass, harvest index and yield under moderate and high plant population densities. The study was conducted in the field at Saskatoon and Swift Current, Saskatchewan, in 2003 and 2004. The experimental treatments consisted of a factorial combination of six commercial kabuli chickpea cultivars representing the two leaf types and two plant population densities: 45 and 85 plants m-2. There were no cultivar and plant population interactions for crop growth rate, maximum above-ground biomass, harvest index and seed yield. Dry matter production was higher in the 2004 season, which had above-average rainfall and a longer duration of reproductive growth. Although high plant population exhibited higher maximum above-ground biomass in 3 location-years, plant population did not affect the crop growth rate. The 45 plants m-2 treatment had a higher harvest index than the 85 plants m-2 treatment in 2 location-years, but both population treatments were similar in the other two environments. Yield of chickpea was increased by higher plant population in 1 location-year, but was not affected by plant population in the other location-years. The fern leaf cultivars had a higher crop growth rate over the unifoliate leaf cultivars in 2 location-years and no significant difference in the other environment. Fern-leaf cultivars partitioned more dry matter to seed growth compared with unifoliate cultivars while sustaining similar biomass production as unifoliate cultivars. The use of fern-leaf cultivars in the Northern Great Plains appears to be an opportunity for increasing chickpea yield by its superior harvest index compared with unifoliate leaf cultivars. Key words: Cicer arietinum, fern leaf, unifoliate, plant population, seed yield

The relationship between several autumn growth traits and winter survival was determinedin 11 diverse safflower (Carthamus tinctorius L.) accessions grown at Central Ferry and Pullman, WA, USA. The safflower was sown in September 2002 and 2003 and plant population counts were taken 6-8 wk after emergence, and after the last frost in the spring to calculate winter survival. Growth factors including plant habit and height were also measured in the autumn. The Pullman plots in 2003–2004 were lost during an usually cold and windy November, but otherwise survival ranged from 90% for BJ-27, an introduction from China, to zero for the cultivar Saffire. Winter survival was negatively correlated with more upright plant habit (r = -041**, n = 97) and plant height (r = -0.29**, n = 97). However, some accessions with low plant habit (prostrate growth) and low height values had relatively poor survival. The results show that BJ-27 has sufficient winter survival to achieve over-winter safflower production for many areas. Autumn plant habit and height can predict the potential for winter survival, but physiological factors related to cold acclimation appeared to determine if that potential is realized. Key words: Carthamus tinctorius, safflower, winter hardiness, cold tolerance

Ball, R. A., Hanlan, T. G. and Vandenberg, A. 2006. Stem and canopy attributes that affect lodging resistance in lentil. Can. J. Plant Sci. 86: 71‐81. Many lentil (Lens culinaris L.) cultivars currently grown in Western Canada are susceptible to lodging. The objective was to determine if plant traits associated with lodging but independent of environmental influences could be used for indirect selection of lodging resistance. For a range of canopy variation, eight genotypes were grown at three plant population densities in the field in 2001 and 2002 at five locations. Four unadapted genotypes (designated FLIP), varying in plant profile and stem stiffness, were compared with locally adapted cultivars. Lodging is a complex trait and was influenced by both genetic differences among the genotypes and environmental conditions. Large green market class cultivars had weak stems and lodged easily. As the canopy’s ability to recover from crushing increased, lodging increased due to greater plant biomass. The greater the fiber content in the plant stems, the more biomass and more lodging occurred. Genotypic ranking of stem diameter was consistent across locations, and stem diameter may be used to indirectly select for lodging resistance. From regression analysis, stem diameter and lodging were described by branch number, recovery from canopy crushing, plant density, height, stem fiber content and lignin content; branch number, plant density and plant height were the most influential terms. For screening lodging resistance in crosses made from a lodging resistant genotype and a highly lodging susceptible genotype, selection of progeny with the smallest stem diameter should be the most lodging resistant, although yields will be reduced. Selection procedures would involve seeking large diameter stems but with similar stem traits of the small-stemmed FLIP lines.

The use of bacterial inoculants can increase root nodulation and the seed yield of annual legumes. A six site-year study was conducted to determine the effect of formulations (peat-based powder vs. granules) and placement in the soil (seed-row vs. side-band) of Mesorhizobium inoculants on plant establishment and seed yield of chickpea (Cicer arietinum L.) in the semiarid Canadian prairies. Two market classes of chickpea, namely desi and kabuli, were grown on silt loam and heavy clay soils in southwestern Saskatchewan from 1999 to 2002. Inoculation reduced plant population by 10% for desi chickpea, but had no effect on kabuli chickpea. However, the use of inoculant increased seed yield by an average of 35% for desi chickpea and 7% for kabuli chickpea. On the heavy clay, soil inoculation increased seed yield by 16% for desi and 9% for kabuli compared with seed inoculation, whereas the yield increase due to soil inoculation, over seed inoculation, was 3% when the crops were grown on the silt loam. Granular inoculant applied in the seed row produced similar seed yields to side-banded inoculant. Inoculation delivery systems had a marginal impact on plant height, with no effect on the lowest pod height from the soil surface or days to maturity. Regardless of placement, soil inoculation with a granular form of Mesorhizobium was preferred over seed inoculation because of its greater positive impacts on plant establishment and seed yield for both desi and kabuli chickpea in this semiarid region. Key words: Cicer arietinum, seed weight, heavy clay, silt loam, harvestability

Chickpea (Cicer arietinum L.), an annual grain legume, is being broadly included in cereal-based cropping systems throughout the semiarid Canadian prairies, but information on optimum plant population density (PPD) has not been developed for this region. This study, which was conducted from 1998 to 2000 in southwestern Saskatchewan, determined the effect of PPD on field emergence, seed yield and quality, and harvestability of kabuli and desi chickpea compared with dry pea (Pisum sativum L.). Seed yields of all legumes increased with increasing PPD when the crops were grown on conventional summerfallow. The PPD that produced the highest seed yields ranged from 40 to 45 plants m-2 for kabuli chickpea, from 45 to 50 plants m-2 for desi chickpea, and from 75 to 80 plants m-2 for dry pea. When the legumes were grown on wheat stubble, the PPD that gained optimum seed yield ranged from 35 to 40 plants m-2 for kabuli chickpea, from 40 to 45 plants m-2 for desi chickpea, and from 65 to 70 plants m-2 for dry pea. The proportion of large-sized (>9-mm diameter) seed in the harvested seed was >70% when the kabuli chickpea was grown on summerfallow regardless of PPD, whereas the large-seed proportion decreased with increasing PPD when the crop was grown on wheat stubble. Increases in PPD advanced plant maturity by 1.5 to 3.0 d and increased the height of the lowest pods from the soil surface by 1.4 to 2.0 cm (or 5 to 10%), with desi chickpea receiving the greatest benefits from increased PPD. The percentage of plants established from viable seeds per unit area decreased substantially as PPD increased, with kabuli chickpea emergence decreasing from 90% at PPD = 20 plants m-2 to 72% at PPD = 50 plants m-2, from 81 to 69% for desi type, and from 83 to 59% for dry pea . The reason for the low field emergence with increased PPD is unknown, but methods which lead to improved field emergence represent a great opportunity to increase seed yield and reduce production costs for both chickpea and dry pea in this semiarid region. Key words: seed size, Cicer arietinum, Pisum sativum, seeding rate, summerfallow

Early processing tomato (Lycopersicon esculentum Mill.) cv. H9230 and N 1045 were field grown with three row arrangements and two plant population densities in 1999, 2000 and 2001 to investigate their effects on fruit yield, quality, and foliar and fruit diseases. An equidistant single row arrangement (75/75 cm) resulted in similar or higher yield compared with the two less-even twin row arrangements (60/90 cm and 40/110 cm) over the 3 yr. The equidistant single row arrangement (75/75 cm) and wide twin row arrangement (60/90 cm) had reduced foliar and fruit diseases in a wet year (2000). However, the incidence of blossom-end rot was greater in the equidistant single row arrangement in a dry year (2001). Increasing the plant density from 33 300 to 40 400 plants ha-1 by reducing the plant spacing within the row from 40 to 33 cm increased the yield by 3–5 t ha-1. Row arrangement or plant density did not affect fruit size or soluble solids. Fruit size and soluble solids of H9230 were consistently greater than those of N1045 in all 3 yr. For production of early, small-vined processing tomatoes in southwestern Ontario, an equidistant single row arrangement with a plant density of 40 000 plants ha-1 is suggested. Key words: Lycopersicon esculentum, tomato, processing, yield, soluble solids, blossom-end rot

Injury to sunflower (Helianthus annuus L.) caused by hail and pests can result in financial losses to producers. This field study was conducted to determine the response of sunflower to different types and levels of physical injury. The information will assist producers in deciding whether to replant or maintain a crop. Studies were conducted at four North Dakota locations. Treatments consisted of stand reduction, terminal bud removal, and top one third of the plant cut off, imposed on either 25 or 50% of an established plant population at five stages of plant development. Plant response to injury varied among treatment stages. When plants were injured at vegetative stages V4 and V8, 98.2 and 93.2% of the treated plants produced multiple branches and heads. When plants were injured during the transition from vegetative to reproductive development (V12, R1), a greater proportion (26.1 and 20.6%, respectively) of the plants died. The majority of the plants injured at stages R1 and R3 neither died nor branched (55.5 and 96.1%, respectively); they continued to live but did not produce seed. Living injured plants reduced total crop yield more than the injured plants that died, since living injured plants continued to compete with uninjured plants for space, light, nutrients and moisture but did not contribute toward yield. Key words: Sunflower, Helianthus annuus L., hail, crop injury

The effects of the herbicide trifluralin on the incidence of flax wilt and agronomic traits were investigated in several flax cultivars in established fields with high, and low infestation of F. oxysporum f.sp. lini. Trifluralin was applied in the fall and seeding carried out the following spring. Trifluralin negatively interacted with fusarium wilt, reducing plant emergence by 42–68%, and the final plant population by 36–60% in several cultivars. Trifluralin reduced the incidence of post-emergence wilt and late-wilt. The reduced post-emergence disease incidence was perhaps due to poor emergence and low plant population which left fewer plants to be infected. The interaction of trifluralin with this fungus reduced yield (17–60%) in most cultivars in highly infested fusarium soil. In low-infested soil, trifluralin significantly increased yield in most cultivars (8–44%). The significant trifluralin and wilt interaction also resulted in increased plant height. Key words: Linum usitatissimum, Fusarium oxysporum f.sp. lini., trifluralin, flax wilt

Row cover and plant population density effects were studied at the Agriculture Canada Research Station, Agassiz, BC in 1988 and 1989. Bell pepper plants (Ace Hybrid) were transplanted into twin rows (0.45 m apart) on raised beds (1.8-m centers) at five population densities of 1.39, 1.85, 2.78, 5.56 and 11.1 plant m−2. For 7 wk in 1988 or 8 wk in 1989, subplots were either covered or not covered with slit clear polyethylene tunnels. A nonlinear regression model was used to define yield-population density responses. Row covers enhanced early and overall yields in 1988 and overall yield in 1989. Vegetative and reproductive yields (kg plant−1) declined with increasing plant population density. Yields were directly related to population density when measured on a land-area basis. Maximum fruit yield (7.9 kg m−2) was obtained at the highest population density. Treatment influences on fruit size were small and did not affect horticultural quality. An economic analysis showed that net returns were greatest with plants grown under row covers at the highest population density.Key words: Capsicum annuum L., field bell peppers, population density, row covers

The response to salinity of a tissue culture derived, salt-tolerant selection (STS) of flax (Linum usitatissimum) was measured at three saline-affected field sites in Saskatchewan in 1985 and 1986. Two experiments were conducted at each site in each year. Experiment A compared the plant population, dry matter yield and seed yield of STS to its parent cultivar McGregor. Experiment B compared the plant establishment, growth rates, days to flower, days to mature and seed yield per plant of STS, McGregor and the cultivar Noralta which has a maturity similar to STS. The seed yield of McGregor was greater than that of STS in both saline and nonsaline conditions and was significantly less affected by salinity than STS. However, when equal numbers of seeds were sown, more STS plants survived to maturity than either McGregor or Noralta. The decrease in seed yield per plant with increasing salinity was usually greater for McGregor and Noralta than STS and sometimes significantly so. The maturity differences among McGregor, STS and Noralta were not correlated with the differences in seed yield per plant. There was no consistent pattern in the results to suggest that STS was more saline-tolerant than were flax cultivars developed using conventional breeding procedures.Key words: Linum usitatissimum, somaclonal variation, salinity response

Hybrid sunflowers (Helianthus annuus L.) have rapidly replaced open-pollinated cultivars in the United States in the past 5 yr. Because of differential performance or economic considerations, hybrids of several other crops are grown at different plant populations than the standard cultivars that they replaced. This study was conducted to ascertain whether previous recommendations at plant populations for open-pollinated cultivars are appropriate for hybrids. The performance of three hybrids was compared with the major open-pollinated cv. Peredovik, at plant populations of 36,000, 48,000, and 72,000 plants/ha over 3 yr, 1973–1975. A nonsignificant cultivar × population interaction indicated that the three hybrids and Peredovik responded similarly to changes in plant population for each of the 3 yr of testing. Yield, oil content, and test weight were not significantly altered by the three plant populations evaluated. As plant population increased, head size and seed weight decreased and plant height of the hybrids and days to flowering increased. It was concluded that plant population recommendations for Peredovik of about 48,000 plants/ha are also appropriate for the growing of hybrids.

Plant population effects on yield and maturity were measured on forage corn over 4 yr at Charlottetown, P.E.I. Populations ranged from 39,000 to 80,000 plants/ha and had relatively little effect on forage yields. Yields varied from 4,887 kg/ha to 15,289 kg/ha, but the variation was mostly related to seasonal effects. Whole plant percentage dry matter contents, though in the low 20’s, were typical for the area and were essentially unaffected by population. The percentage dry matter in the grain tended to decrease at the higher population, but only significantly so in 2 yr (P = 0.1). High population retarded silking dates. In the 3 yr that tissue nutrient concentrations were measured, increasing population had little effect on total nutrient uptake but significantly reduced whole plant nutrient concentrations in 1 yr (P = 0.05). Under the climatic conditions of the Atlantic area, field stands of 50,000–80,000 plants/ha appear suitable for forage corn.

The effect of seeding date, seeding rate, row spacing and fertilizer level were investigated in two cultivars of lentil (Lens culinaris Medik.), Eston and Laird, in Manitoba. High yields were obtained by early seeding, narrow row spacing (15 cm) and high seeding rate (100 plants m−2). Response to fertilizer levels was variable. Early seedings produced larger seeds. Effects of other treatments on seed size were not significant.Key words: Lentil, seeding date, seeding rate, plant population, fertilizer level

Studies at Hyderabad, India, and Swift Current, Saskatchewan, Canada, have shown that sunflower (Helianthus annuus L.) can be grown under dryland conditions over a wide range of plant populations and row spacings. At Hyderabad, yield plateaus of approximately 900 and 1,350 kg/ha existed over population ranges of 18,000 to 32,000 and 56,000 to 98,000 plants/ha, respectively. At Swift Current, yields from a 25,000 plants/ha population were 28% higher than those of a 125,000. plants/ha population, but were not significantly different from the mid-range 75,000 plants/ha. Population also influenced growth characteristics such as plant height and stem diameter and the rates of development. The crop showed a remarkable tolerance to drought and the ability to recover after periods of extreme moisture stress. Populations of 60,000 to 75,000 plants/ha at row spacings of 35 to 60 cm are recommended for dryland production.

To study the effect of increases in plant density on the dry matter (DM) yield, percentage grain and percentage DM content of whole-plant maize (Zea mays L.), 12 tests were established over a 3-yr period in Central and Southern Ontario. Each test involved three adapted hybrids grown at 50 000, 63 000 and 75 000 plants/ha in 1976, and at these three densities plus 92 000 plants/ha in 1977 and 1978. No hybrid-by-density interaction for DM yield occurred in any test, and the density response was similar for most tests. Maximum DM yield was generally attained once density increased to 63 000 plant/ha. Plant population had a negligible effect on the grain percentage of DM content of forage up to 75 000 plants/ha. Optimum density for DM yield was much lower than expected, given the small stature (i.e., leaf area/plant) of adapted hybrids grown in most of Ontario.

Two tomato (Lycopersicon esculentum Mill.) cultivars, Heinz-2653 and Campbell-28, were grown on Fox loamy sand in the subhumid region of southern Ontario from 1979 to 1982. Irrigation increased the marketable yields of H-2653 in a dry year, 1982, but not in the other years. Irrigation substantially increased marketable yields of C-28 in 1979 and 1982. Irrigation, when the available soil moisture (ASM) level reached 50%, was no more effective than when the ASM level in the soil was allowed to drop to 25%. Without irrigation yield increased as plant population increased in normal and wet years, but not in a dry year. Blossom-end rot (BER) of C-28 cultivar was markedly reduced by irrigation. Effects of irrigation or plant population treatments on the incidence of fruit speck did not appear to be significant.Key words: Available soil moisture, Lycopersicon esculentum, Pseudomonas syringae pv. tomato, fruit speck

High-density (32 plants/m2) planting of soybeans [Glycine max (L.) Merrill] resulted in small plants but high dry weights per unit area of ground, while low density (four plants/m2) produced larger plants with a smaller dry weight per unit area of ground. Intermediate densities (16 and 8 plants/m2) produced intermediate plant sizes and yields. Shoot/root, bean/shoot, and leaf area ratio were all decreased by increasing density. The effects of density on plant growth were detectable 30 to 40 days from planting, and increased rapidly thereafter.Fertilizer in moderate quantity depressed the growth of the whole plant in the early stages, but, by maturity, fertilizer was associated with a small increase in weight of shoot and an increase in the proportion of beans to shoot.High density reduced the proportion of flowers forming mature pods, while fertilizer application increased it.There was no interaction between fertilizer level and density of planting on any plant characteristic.Effects of fertilizer on later stages of growth could be attributed mostly to N; effects on early stages of growth are more difficult to interpret but suggest an extreme sensitivity to fertilizer, which may be involved in the generally observed poor response of soybeans to fertilizer.

Increases in plant population of field corn resulted in increased stalk rot and barrenness, and decreased tillering and ear size. In the stalk rot susceptible single cross CH159 × CH3, stalk rot reached high levels at relatively low populations (10- and 15-thousand plants per acre) whereas resistant B14 × CH9 did not have stalk rot below populations of 20- and 25-thousand plants per acre. Stalk rot did not occur until after the plants had reached physiological maturity. Plants which developed stalk rot shortly after physiological maturity had lower grain yields than plants which developed stalk rot later in the autumn. Plants without stalk rot by the time of final harvest in late October or early November were found to have either well-developed ears with high grain weights or small, poorly pollinated ears. It was concluded that both stalk rot and reduction of grain yield are the end results of conditions which reduced plant productivity during growth.

Soluble solids in stalks of two short-season corn (Zea mays L.) hybrids accumulated until 2–3 weeks after anthesis, and then declined rapidly during the grain-filling period. Soluble solids concentration was unaffected by plant population, but greatest total soluble solids accumulated at high plant populations. Most of the soluble solids that accumulated and disappeared were in internodes below the ear. When pollination and grain development were prevented, total soluble solids in stalks increased until the end of the growing season, indicating that the decline in stalk soluble solids during grain filling was caused primarily by translocation of metabolites from the stalk to the grain.

The effect of spacing and nitrogen fertilizer levels on some agronomic, physical, and chemical characteristics of two varieties of cigar tobacco were compared over a 3-year period.At each of two nitrogen fertilizer levels, the variety Pennsylvania Broadleaf, irrespective of plant spacing, produced higher yields and returns per acre, more leaves per plant and weight per leaf, but a higher percentage of midrib and yellow trash leaf than the variety Resistant Havana 211. Although the differences between the varieties at each nitrogen level were relatively unaffected by plant spacing, the 20-in. spacing caused a decrease in yield, crop returns, and percentage of yellow leaf and an increase in weight per leaf and percentage of filler leaf from that obtained with the 16-in. spacing. An increase in nitrogen fertilizer from 24 to 60 lb per acre had little effect on Resistant Havana 211 other than to increase the weight per leaf. The additional nitrogen with Pennsylvania Broadleaf, however, increased the yield, crop returns, weight per leaf, and percentage of filler leaf. The variation in rate of nitrogen fertilizer had little effect on grade index, number of leaves per plant, and percentages of nicotine, nornicotine, and total alkaloids in both varieties.The combination of 16-in. spacing with 60 lb of nitrogen was superior to other combinations of 16- or 20-in. spacing with 24 or 60 lb of nitrogen per acre for the production of cigar filler leaf in each of two varieties.

Spring wheat seeding rates of 22, 45, 67, and 101 kg/ha were compared in a field experiment on a medium-textured soil at Swift Current, Saskatchewan, over the period 1960–1968. Data collected during eight years indicated that when weeds, insects and diseases were chemically controlled, low seeding rates produced significantly more grain than higher seeding rates, with greatest increases occurring during years of severe moisture stress. Low seeding rates produced longer heads, heavier kernels, and in some cases taller plants. Plant population differences resulting from the variation in seeding rate were largely eliminated by plant survival and tillering. The number of mature kernels per unit area did not differ significantly for all treatments.Seeding rates had an effect on the rate at which moisture was used by the crop. Soil moisture supplies were quickly exhausted on plots seeded at rates of 67 and 101 kg/ha, whereas moisture was available to the crop seeded at lower rates over a longer period. The crop seeded at 22 kg/ha matured 3 to 5 days later than that seeded at 101 kg/ha.

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Net assimilation rate (NAR), relative growth rate (RGR) and relative leaf growth rate (RLGR) of soybeans [Glycine max (L.) Merrill] declined throughout the season; much of this decline and most effects of plant population on growth could be attributed to a rise in leaf area index (LAI). Increase in LAI from 0.3 to 1.0 was associated with a marked decrease in NAR. Crop growth rate (CGR) increased for the first 50 to 60 days, falling sharply thereafter. There was no optimum value of LAI.Fertilizer increased final plant weight mainly by delaying the fall in NAR and CGR. LAI was increased slightly by fertilizer application, presumably because of a higher RLGR between 50 and 70 days.The classical and regression techniques of growth analysis gave similar results, but the lower standard errors obtained with the latter revealed additional treatment effects. In some circumstances, smoothed curves used to describe growth might conceal growth fluctuations due to environmental stress.