Canadian Journal of Plant Science
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PLANT-TO-PLANT VARIABILITY OF MAIZE PLANTS GROWN AT DIFFERENT DENSITIES Development of plant-to-plant variability in plant height, flowering characteristics and grain yield was studied in two maize (Zea mays L.) hybrids grown over 2 yr at 62 000, 93 000 and 124 000 plants/ha. The purpose of the research was to provide fundamental data on patterns of interplant variability in maize, as a foundation for more applied studies on effects of cultural practices on within-crop variability and yield. Plant height was normally distributed early in the season but tended to become negatively skewed as the plants grew. The same tendency for negative skewness existed in calculations of rate of elongation. The standard deviations of height and of rate of elongation increased as plants enlarged. Frequency distributions of days to anthesis or silking were positively skewed as was the distribution of number of days from anthesis to silking at high density. The standard deviations of days to silking, and days from anthesis to silking increased with increasing density. Grain yield per plant was normally distributed or slightly skewed negatively, with barren plants not considered. With the latter included, frequency distributions were bimodal at higher densities. The standard deviation of plant height increased as the crop developed although the coefficient of variability of height declined. Plants which were initially short did not "catch up" in height until after flowering had begun. Taller plants tended to anthese and silk earlier and produce more grain; in general, these associations were stronger with measurements of height taken prior to flowering than after. Date of silking was more closely related to yield than date of anthesis. On average, plants destined to be barren were shorter than the population mean on all dates of measurement and retarded in development. However, many plants became barren which were taller than average and earlier than average in date of flowering.Key words: Competition, maize, barrenness, grains, height, silking
Canadian Journal of Plant Science - Tập 63 Số 1 - Trang 45-59 - 1983
Chemical composition and antibacterial activities of<i>Juniperus horizontalis</i>essential oil Eryiğit, T., Okut, N., Ekici, K. and Yildirim, B. 2014. Chemical composition and antibacterial activities of Juniperus horizontalis essential oil. Can. J. Plant Sci. 94: 323–327. In recent years, the screening of antibacterial activity has been the subject of much research, and the antibacterial activity of essential oils could be a promising subject for future investigation. In this study, the antibacterial activities of Juniperus horizontalis essential oils and their components were investigated. Essential oils were isolated using the hydro-distillation method and their components were analyzed by gas chromatography–mass spectrometry (GC-MS). The main compounds found in the oil of leaves were linalool (33.76%), P-cymene (23.20%), gamma-terpinene (8.67%), trans-sabinene hydrate (8.59%), thyme camphor (8.49%), carvol (5.08%) and borneol (4.22%). Juniperus horizontalis essential oils were evaluated for antibacterial activity against six bacterial strains using the disc diffusion method. The results indicate that the essential oil of J. horizontalis shows variable and significant antibacterial activities against the six tested bacteria species. The diameters of the inhibition zones formed for bacteria were measured. The lowest inhibition zone was 12 mm (sensitive) against Pseudomonas aeruginosa ATCC 10145 and the highest zone was 32 mm (extremely sensitive) against Enterococcus faecalis ATCC 29212.
Canadian Journal of Plant Science - Tập 94 Số 2 - Trang 323-327 - 2014
RAPID DETERMINATION OF SEED GERMINATION POTENTIAL TO MEASURE QUALITY LOSS IN STORED WHEAT A rapid method of determining wheat seed germination after 1 day (G1) of incubation was found. Germination of wheat seed stored at [Formula: see text] moisture content is estimated by adding 12% to G1; at <17% moisture content germination is not consistently predicted by G1.
Canadian Journal of Plant Science - Tập 62 Số 4 - Trang 1045-1048 - 1982
IMPACTS OF FREEZING TEMPERATURES ON CROP PRODUCTION IN CANADA Subzero temperatures are the most widespread hazard to crop production in Canada. This hazard ranges from temperature occurrences near 0 °C in spring and fall that damage many annual crops and some perennials to the winter occurrences of −30 °C and lower that damage or kill vegetative and/or reproductive tissues of some perennial species. Terminology, types of freeze damage, and the freeze risk are reviewed and discussed here along with some examples of the occurrence and adverse impact of freezing temperatures for the range of annual, winter annual and perennial crops grown in Canada. Spring grain losses from freeze damage occur about once every 3–4 yr in Saskatchewan, less frequently in Alberta (except the Peace River region), Manitoba and the northern clay belts in Ontario and Quebec, and seldom in the remainder of eastern Canada. Frequency of canola losses on the Prairies has been similar to cereals over the past 10–12 yr. The availability of short-season corn and soybean cultivars has expanded the production of these crops to areas with fewer than 2300 heat units over the last 20 yr. This has resulted in more frequent losses of these crops from fall freezes. Major losses of seed-corn occurred in southwestern Ontario on three occasions from 1965 to 1974, but very little freeze damage has occurred since 1974. Losses of vegetable crops from freezing occur less frequently than other crops because of the well-established cultural practices developed over the years that avoid or protect from frost. The high value per unit area of most vegetables makes freeze protection more affordable when needed. Forages and winter annuals are killed more frequently in central and eastern Canada by smothering and desiccation from formation of ice sheets than from low winter temperatures. Injury to young shoots and leaf buds of these crops occurs periodically from spring freezes. Losses of fruit trees occur periodically and apparently occurred more frequently 20–35 yr ago in British Columbia, whereas losses have been more severe in recent years in eastern Canada. Major declines in tender fruit production occur once or twice every 5–10 yr depending on location. Temperatures of −30 °C or lower may kill the tender fruit trees and −25 °C may damage the buds in winter, although late spring frosts during bloom reduce production more frequently.Key words: Frost hazard, crop losses, indemnities
Canadian Journal of Plant Science - Tập 67 Số 4 - Trang 1167-1180 - 1987
Influence de l'indice foliaire et des réserves en hydrates de carbone au moment de la coupe sur la croissance foliaire de deux graminées fourragères (<i>Dactylis glomerata</i> L. et <i>Festuca arundinacea</i> Schreb.) Leaf growth of two forage grasses (Dactylis glomerata L. and Festuca arundinacea Schreb.) was studied as a function of the sward state after a cut. Two heights of cut (3 and 6 cm) and a variable number of previous cuts were used to reach different residual leaf area index (IFr), and non-structural carbohydrate (CNS) concentration and quantity. For both species, four treatments were studied in 2 consecutive years. In mid-May for each of the species, the IFr ranged from 0 to 1, and the quantity of CNS varied from 12 to 25 g 100 g−1 DM according to the treatments. Over the 3 wk of regrowth, the IF reached values ranging from 1 to 7 and its increase depended on the IFr and the quantity of CNS. Among the three components of the quantity of CNS (weight of sheath per tiller, tiller density and CNS concentration), only the first two had a significant effect on the IF increase. Tiller mortality occurred when the quantity of CNS or the IFr were the lowest and it contributed little to the growth of lower leaves. No significant differences were found between the two species. Key words: carbohydrates, leaf area index, tiller, cut
Canadian Journal of Plant Science - Tập 76 Số 2 - Trang 269-276 - 1996
Morphogenetic characteristics of timothy grown with varying N nutrition The leaf area development of grasses and subsequently radiation interception depends on morphogenetic processes such as leaf extension and appearance. Leaf extension and appearance of timothy (Phleum pratense L.) grown with varying rates of N nutrition and their impact on sward structural characteristics were studied during primary growth in spring and during a summer regrowth. With no N applied in spring and summer, the leaf extension rate (LER) and the leaf appearance rate (LAR) of timothy were approximately 40% and 65% of that obtained under non-limiting N conditions (140 kg N ha−1 in spring and 120 kg N ha−1 in summer). Nitrogen deficiency reduced tiller density in spring but increased it in summer. The differential effect of the N deficiency on LER and LAR modified the sward structural characteristics. Nitrogen deficiency decreased the length of mature leaves, their width and the total leaf length per tiller. The reduced LER associated with N deficiency explained for the most part the N effect on leaf area expansion and radiation interception. Key words: Phleum pratense L., timothy, leaf extension, leaf appearance, tillering, nitrogen
Canadian Journal of Plant Science - Tập 78 Số 1 - Trang 103-108 - 1998
Morphogenetic and structural characteristics of field-grown timothy cultivars differing in maturity The leaf area development of grasses and, subsequently, radiation interception depends on morphogenetic processes such as leaf extension and appearance. No detailed studies of leaf extension and appearance of field-grown timothy (Phleum pratense L.) cultivars differing in maturity have been reported in the literature. Leaf extension and appearance of field-grown timothy cultivars differing in maturity and their impact on sward structural characteristics such as leaf size per tiller and tiller density were studied during primary growth in the spring of 1991 and 1992. The leaf extension rate of early-maturing cultivars was greater than that of late-maturing cultivars during primary growth of timothy. There were no differences in leaf appearance rates among cultivars Hence, individual tillers of early-maturing cultivars developed a larger leaf size than late-maturing cultivars. In 1992, late-maturing cultivars had a greater tiller density than early-maturing cultivars which compensated for the smaller leaf size. Different tiller density-tiller size characteristics of early and late-maturing timothy cultivars resulted in a similar outcome in terms of LAI. Key words:Phleum pratense L., timothy, leaf extension, leaf appearance, tillering
Canadian Journal of Plant Science - Tập 76 Số 2 - Trang 277-282 - 1996
Growth analysis of timothy grown with varying N nutrition Nitrogen fertilization increases yield of timothy (Phleum pratense L.) but little knowledge exists on the effect of N fertilization on the growth processes of field-grown timothy. The objective of this study was to analyze the growth of timothy fertilized with increasing rates of N in spring and summer and, in particular, to determine the relative importance of radiation interception and radiation-use efficiency in explaining the differences in shoot growth caused by N deficiency. In two separate experiments conducted in spring 1993 and summer 1994, shoot growth, leaf area development, radiation interception and radiation-use efficiency of timothy grown with four N rates (0, 70, 140 and 210 kg N ha−1 in 1993; 0, 60, 120 and 180 kg N ha−1 in 1994) were determined using weekly sampling. Maximum leaf photosynthesis was also measured. The maximum shoot growth and LAI were reached with 140 kg N ha−1 in the spring of 1993 and 120 kg N ha−1 in the summer of 1994. The rates of N fertilization required to produce these maximum values of shoot growth were those that resulted in shoot N concentration equal to or greater than the optimal N concentration. The concept of an optimum N concentration was therefore useful in identifying situations of N deficiencies. When no N was applied, the growth rates were 32 and 33% of the maximum growth rates in spring and summer, respectively. The impact of the N deficiency was greater on RUE than on cumulative intercepted PAR. When no N was applied, the RUE and cumulative intercepted PAR were respectively 45 and 61% of their maximum values in spring, and 52% and 80% of their maximum values in summer. A general and synthetic expression of the effect of crop N concentration on shoot growth was developed using the concept of an optimal N concentration. Key words: Phleum pratense L., timothy, growth, radiation, photosynthesis, nitrogen
Canadian Journal of Plant Science - Tập 77 Số 3 - Trang 373-380 - 1997
Growth analysis of timothy cultivars differing in maturity The delay in ear emergence or heading between early and late-maturing timothy (Phleum pratense L.) cultivars can be up to 3 wk. The objective of this study was to determine the relative importance of radiation interception and radiation-use efficiency in the differences in shoot growth between early and late-maturing timothy cultivars. During the primary growth in 1991 and 1992, four timothy cultivars differing in maturity were compared for shoot growth, leaf area development, radiation interception and radiation-use efficiency using weekly samplings. Stem elongation of early-maturing cultivars progressed faster than that of late-maturing cultivars. Early-maturing cultivars had greater shoot growth and RUE than late-maturing cultivars. Differences in cumulative intercepted PAR among cultivars were relatively small compared with cultivar differences in RUE. Hence, the greater shoot growth of early-maturing cultivars compared with that of late-maturing cultivars was attributed to a greater RUE of the early-maturing cultivars. Consequently, different values of RUE should be used for early and late-maturing timothy cultivars in crop models based on efficiencies of radiation interception and utilization. Key words:Phleum pratense L., cultivars, growth, radiation, photosynthesis
Canadian Journal of Plant Science - Tập 75 Số 3 - Trang 643-648 - 1995
Impact of excess moisture due to precipitation on barley grain yield in the Canadian Prairies Variance analysis was performed on the effect of monthly accumulated precipitation data (May–July) on crop losses between 2005 and 2016 with combined Manitoba and Saskatchewan regional barley grain yield data. A significant negative relationship with total precipitation during May to June was observed. This period coincides with leaf emergence to the booting stage in barley.
Canadian Journal of Plant Science - Tập 99 Số 1 - Trang 93-96 - 2019
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