Showing papers on "Sowing published in 1982"

Ryegrass endophyte, incidence, and control

Abstract: There was a high incidence of a fungus endophyte in most of the perennial ryegrass pastures and seed lines examined. The fungus was still viable in seed which had been stored at 0–5°C for 7 years. The main means of endophyte dissemination appear to be the sowing of infected seed and the re-seeding of infected plants in pastures. Field observations showed that when endophyte-free seed was sown, a set of mown plots and a grazed pasture were still free of endophyte 4 years after establishment. Endophyte-free seedlings were obtained by treating infected seeds with the fungicides propiconazole or prochloraz at 0.5 g/kg of seed. The fungus was eradicated from infected plants growing in pots by drenching the soil with a suspension of benomyl at 0.1 g per litre of growing medium.

Root development and growth of oilseed, wheat and pea crops on tilled and non-tilled soil

Abstract: Field experiments were done on red brown earth soils at two sites in South Australia between 1979 and 1981. The effects of different amounts and types of tillage on root growth and plant development were compared for linseed, pea, rape, safflower, soybean, sunflower and wheat. Crops were grown in 2 × 1.5 m2 plots with the following treatments: (a) tine-tilled to 120 mm; (b) non-tilled with seeds sown in 30 mm slots, (c) non-tilled with seeds sown in narrow, 30 mm deep holes, and (d) and (e) as for (b) but with vertical cracks extending from the base of the slots to depths of 120 and 300 mm, respectivley. In the naturally-compacted non-tilled soil, penetrometer resistance was highly dependent on water content. Treatments (b) and (c) restricted seminal root growth relative to treatment (a), and the degree of restriction was dependent on penetrometer resistance in the post-planting period. Growth of lateral roots was also less in (b) and (c) than in (a). The reductions in early root growth for (b) and (c) were associated with reduced dry matter production and yield of the crops. However, the presence of cracks in (d) and (e) provided a zone for unrestricted root growth and the dry matter production and yields were comparable to those in (a). The magnitude of the reductions in root and dry matter productions for (b) and (c) relative to (a) ranged from 0% to > 50%, depending on the crop and the planting time. On the basis of reductions in dry matter production from (a) to (b), it appears that the suitability of these crops for growth in non-tilled soil decreases in the order: wheat > pea > rape > linseed > safflower and sunflower. In separate experiments, soybean and sunflower suffered similar yield reductions in non-tilled soil.

Effect of sowing date on the temperature response of leaf emergence and leaf size in barley

Abstract: Rate of leaf emergence of barley grown in the field in each of 2 years was affected by sowing date and, where direct comparisons were possible, it was found that leaves on late-sown plants emerged more quickly. Rate of leaf emergence fluctuated throughout the season, slowing almost to zero in the winter. Much of this variation in rate was removed when the number of leaves was plotted against accumulated temperature rather than time. When emergence rates for each sowing were calculated using a common base temperature they were found to be well correlated with rate of change of daylength. However, it was (bund that base temperature as well as temperature response was affected by date of sowing. The pattern of change of size of leaves was also affected by date of sowing. It appeared that in low temperatures and short days, there was no increase in leaf size from leaf position to leaf position. The responses of leaf emergence, extension and final size to date of sowing appear to adapt the plant to grow quickly when sown early but to cease growth and possibly frost-harden at low temperatures.

Soybean Response to Different Planting Patterns and Dates1,3

Abstract: Soybean [Glycine max (L.) Merr.] response to narrow rows (less than 50 cm apart) has been inconsistent in the southern United States. However, a more positive response has been documented in the North Central USA. Lack of suitable herbicides for controlling weeds in narrow row soybeans in the South has slowed acceptance of this practice. Development of more effective herbicides has made narrow row soybean production feasible. Earlier planting dates can take advantage of favorable soil moisture conditions. Soybean plantings following wheat [Triticitm aestivum (L.) em. Thell.] harvest often do not close the crop canopy between rows before flowering when planted in rows 92 cm or more apart. Experiments were conducted in 1978 and 1979 (Vertic Haplaquept soils) to determine the effects of row spacings, broadcast seeding, planting dates, and soybean cultivars on yield and other plant characters. Seed yield was affected by row spacing or methods, planting dates, years, and planting dates x years. Cultivars and the cultivar x planting method interaction were not significant for yield but none of the cultivars used in the study had been selected for narrow row conditions. The 18 and 48 cm row widths produced 15% higher seed yields than the conventional 96 cm row spacing. Mean yields across row spacings (including broadcast planting) and cultivars for the 15 July planting date were less than 50% of the April or May plantings. The cultivar x planting date interaction was large for percent seed protein because the late planted Forrest cultivar was significantly lower in percent protein compared to earlier planted Forrest. Pods per plant were significantly associated with yield in 1979 but not in 1978.

Quantification of allelopathic potential of sorghum residues by novel indexing of richards' function fitted to cumulative cress seed germination curves.

Abstract: The inhibitory activity of aqueous extracts of field-grown sorghum (Sorghum bicolor cv. Bird-a-boo) herbage and roots was quantitatively indexed by three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination: the germination onset; weighted mean rate; and final germination percentage. Extract potency was greatest for herbage collected four weeks after planting but declined sharply thereafter as the plants matured. About 91% of the inhibitory activity obtained from four-week-old herbage was in a low molecular weight fraction. Differential effects of herbage and root extracts on cress seed germination suggest that the nature and/or proportion of biologically active substances extractable from these plant parts is dissimilar.

Growth and Development of Silverleaf Nightshade (Solanum elaeagnifolium)1

Abstract: Controlled - environment studies were conducted to determine the influence of temperature, light, seed weight, depth of planting, substrate pH, and salinity on the germina- tion and emergence of silverleaf nightshade (Solanum elaeagni- folium Cav.). The effects of planting date, top removal, and root-cutting length on establishment were studied in the field. Fluctuating temperatures of 20 to 30C produced 57% germination. Maximum germination, 59%, occurred between pH 6 and 7. NaCl concentrations greater than 2500 ppmw caused germination to decrease 85% or more compared to the control. Light was not important for germination. Mean seedling emergence was 46% from depths of 1.0 to 2.5 cm. Silverleaf nightshade seedling emergence from a 2-cm depth was 31% greater in a sandy soil than a loam. Delayed seeding caused a decline in dry-weight accumulation of above-ground parts. Fifteen percent of seedlings clipped 15 days after emergence were capable of regrowth, and after 30 days or more, 90% of the clipped plants regrew. Additional index words. Planting date, top removal, root length, planting depth, salinity.

Effect of rate and time of fertilization on nitrogen and yield of Russet Burbank potatoes under center pivot irrigation

Abstract: Applying less N on Russet Burbank potatoes (Solanum tuberosum L.) at planting time may reduce the potential loss of N from sandy soil by wind erosion and leaching early in the season. The objective of this study was to evaluate the effect of rate and time of N fertilization on potato production. Potatoes were grown in outdoor pot cultures with N rates of 75,150 and 300 ppm and in field plots with N rates from 112 to 448 kg N/ha applied in single and split applications. The results from pot cultures harvested after one month’s growth showed that yield of tops increased and tuber yield decreased as applied N at planting increased from 75 ppm to 150 or 300 ppm. Field results showed that the yield of potatoes was as high or higher when N applications were split between planting and when plants were 15 to 20 cm tall (early tuberization) as with the same amount of N applied at planting. Generally 112 kg N/ha at planting time was sufficient when additional N was applied after emergence. Split application of N resulted in more second growth on tubers than when all of the N was applied at planting.

The Nitrogen Cycle in Long-Term Field Experiments

Abstract: Nitrogen balance sheets for the Rothamsted Continuous Wheat Experiment show that N fertilizers were used very inefficiently in the past. Thus, over the period 1852-1967, the apparent recovery (in grain and straw) of the fertilizer N applied to the plot receiving 144 kg N ha $^{-1}$ each year was 32%. Recently, however, the apparent recovery of fertilizer N has increased and for the two years 1979 and 1980 the mean value in this plot was 86%. Increased recovery is mainly due to new, high-yielding varieties of winter wheat that take up more fertilizer N, to better control of pests and diseases and to earlier sowing in autumn. Early sowing can increase the amount of N overwintering inside the plant instead of outside in the soil, where it is subject to losses through leaching and denitrification. Recoveries of N by spring-sown barley on the Rothamsted Continuous Barley Experiment were lower than with winter wheat, as would be expected under a cropping system in which the soil is without plant cover from August until March or April. Tentative national N balance sheets for the two major cereal crops in the U.K., wheat and barley, are set out, based on crop survey data. In these balance sheets, between one-third and one-half of the chemically combined N reaching the soil is not recovered in grain and straw. Recoveries of N on the Rothamsted Classical Experiments show that there is considerable scope for improving the recovery of N on a national scale. Research into the quantitative aspects of the nitrogen cycle in the field is needed in order to understand how this N is lost and how the losses can be diminished.

Intercropping Barley and Beans I. Effects of Planting Pattern

Abstract: Barley (Hordeum sativum) and field beans (Vicia faba) were grown in pure stands, alternate-row mixtures and within-row mixtures in two field experiments. In both experiments the Land Equivalent Ratio (LER), based on seed yield, was consistently greater than 1.0 only when the crops were grown in alternate rows. The LER was greatest (1.8) when the mixture included more barley than beans. Reasons for the yield advantage of alternate row planting are discussed. Barley was more competitive than beans in mixtures, but this was not significantly affected by planting pattern.

SEED GERMINATION AND SEEDLING GROWTH CHARACTERISTICS OF ATRAZINE-SUSCEPTIBLE AND RESISTANT BIOTYPES OF Brassica campestris

Abstract: Seed germination and seedling characteristics of atrazine-susceptible and resistant wild turnip rape biotypes (Brassica campestris L.) were examined. Seeds of the susceptible biotype germinated earlier, and the germinated seeds grew faster and emerged earlier than seeds of the resistant biotype. Seedlings of the susceptible biotype emerged from greater planting depths than the resistant seedlings. Emerged susceptible seedlings were larger, with longer hypocotyls and greater cotyledon area, and produced more dry matter than the resistant biotype seedlings. Differences in water content of germinated seeds of the two biotypes were noted, with the susceptible biotypes consistently showing a higher water content. There was no significant difference in the respiration rate of the two biotypes at the early stage of seedling growth.

Modification of water balance of dryland wheat through the use of chlormequat chloride

Abstract: In field trials made for two years in the dry period of a semi-arid tract under natural precipitation at the Indian Agricultural Research Institute, New Delhi, overnight seed-soaking of wheat in 0·5% solution of 2-chloro-ethyl-trimethyl ammonium chloride (CCC) prior to sowing increased the grain yield. When treated with foliar application of the chemical in concentrations ranging between 40 and 1000 mg/1, wheat plots yielded better than did the untreated control, but no consistency was noted between the concentrations or stages of their application. The benefit from CCC was due to more root growth, increased stomatal resistance and higher leaf water potential. Treated plants extracted more water from deeper soil layers, increasing their water-use efficiency.

THE BIOLOGY OF CANADIAN WEEDS.: 52. Achillea millefolium L. S.L.

Abstract: A review is provided of information on the biology of yarrow (Achillea millefolium L., sensu lato) a very complex polyploid group in Canada. Native variants occur across Canada and consist of both tetraploid and hexaploid races. Introduced hexaploids occur predominately in eastern Canada. Yarrow is found as a weed in pastures, meadows, lawns, roadsides and waste places. The species has a wide climatic range and is particularly drought-tolerant. Vegetative spread is rapid, increasing competitive advantage in closed communities, whereas seed reproductive allocation is low. Plants of the species are self-incompatible and insect-pollinated. Factors affecting seed germination are summarized; these include response to temperature, moisture, light, seed age, nitrate ions, sowing depth and fertilizers. Yarrow control in pastures may be provided by 3,6 dichloropicolinic acid or herbicide mixtures containing diclorprop or mecoprop.

Slash-and-Burn Cultivation in the Highlands South: A Problem in Comparative Agricultural History

Abstract: Slash-and-burn cultivation—the practice of clearing temporary fields in forests by chopping and firing the natural vegetation, planting crops for a brief time, and then allowing these fields to revert to forest—is a well-known type of agriculture in the world's tropical environments. Anthropologists, agronomists, and geographers have demonstrated that slash-and-burn cultivation, once regarded as a primitive and wasteful practice, can be an efficient adaptation to tropical forests, where the soils are highly leached, and the bulk of the nutrients available is locked up in the forest vegetation in a nearly closed cycle. By clearing and burning the forest vegetation in a field, slashand-burn cultivators release nutrients accumulated during many years of forest growth in order to fertilize a few years of cultivated crops. When the crop yield in such a field begins to decline, the cultivators abandon it to natural long-term fallow, allowing it to return to forest. The continued success of slash-and-burn cultivation depends on maintaining a high ratio of fallow land to cultivated land to allow for the gradual restoration of forests and nutrients.

Seasonal variation in cowpea crop performance at Ile-Ife, Nigeria and the relationship to insect damage

Abstract: The trends in flowering, podding and seed yield of four cowpea varieties planted at different times of the growing season in 1975 and 1976, were studied along with the associated pest activity. Flowering, podding and seed yield were found to decrease over the season from April to September irrespective of whether the crop was protected against insect pests or not. However, there seemed to be two peak periods of pest activity—April to July and October to December—when severe damage to the crop occurred in unprotected plots. Planting in June or July usually led to an escape from several major pests even though the cool night temperatures and incidence of overcasts at that period seem to preclude optimal reproductive performance of the crop. The pattern of insect pest succession on the crop over the season is discussed and it is suggested that for small farm holders in Southern Nigeria, who are unlikely to apply insecticides, planting in June is advisable.

viability of Rhizobium spp. in liquid inoculants for legumes

Abstract: Summary-Pumping equipment designed for seedbed inoculation of legumes with liquid inoculants was set up on a test bed in the laboratory. Experiments, in which liquid inoculant was circulated through the equipment, were conducted to determine the effect on inoculant viability of variables likely to be encountered when farmers used the equipment in the field. Provided that peat cultures of Rhizobium spp. were used to make liquid inoculant, neither pump type, operating pressure up to 173 kPa, water temperature up to 35"C, nor water impurity up to a level equivalent to 170 @/cm conductivity seriously reduced inoculant populations during the first hour of treatment, although a significant decline in numbers occurred in three out of 16 experiments. When inoculant was exposed to the various treatments for long periods, a significant loss of viability occurred, in 7 out of 13 experiments, between 4-8 h. R. meliloti was least affected by treatment and R. leguminosarum most affected, but this may have been due to strain differences as much as to species differences. Liquid inoculants which were made from broth cultures lost viability very quickly. R. rneliloti liquid inoculant, prepared from a peat culture and introduced by spraying into a dry soil of neutral pH in the absence of any host plant, did not lose viability during a period of four weeks. The spray inoculation equipment was also used successfully in a field experiment to add water to the seedbed to aid in the germination of soybean seed sown into drying soil. Since the first commercial development of legume inoculants in 1896 (Fred et al. 1932), inoculation of legume seed with Rhizobium spp. (rhizobia) has traditionally been performed by applying the inoculant to the seed surface, preferably immediately before sowing. However, there are some situations where application of rhizobia to seed may be an inefficient means of inoculation (Burton 1976; Brockwell 1977). Perhaps the most important of these

Weeds in New Seedings of Alfalfa (Medicago sativa) for Seed Production: Competition and Control

Abstract: Alfalfa (Medicago sativa L. ‘Vernal′) seeded in April in rows 55 cm apart and kept free of weeds produced 820 kg/ha of seed during the year of seeding. Competition from a dense popualtion (40 plants/m of row) of mixed species of annual weeds reduced the seed yield to 45 kg/ha. Competition from a dense population (55 plants/m of row) of broadleaf weeds, a light population (4 plants/m of row) of broadleaf weeds, or a heavy population (75 culms/m of row) of barnyardgrass [Echinochloa crusgalli (L.) Beauv.] reduced yields to 80, 310, and 160 kg/ha, respectively. A weed management system, consisting of EPTC (S-ethyl dipropylthiocarbamate) or profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] applied at or before planting, 2,4-DB [4-(2,4-dichlorophenoxy) butyric acid] applied postemergence, trifluralin (α,α,α- trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) incorporated with the soil when the alfalfa was 20 cm tall, interrow tillage, and a modest input of hand labor brought the crop to harvest free of weeds, and the yields of alfalfa seed were similar to those from plots kept weed-free by hand labor only. When weeds within the rows were controlled by hand labor only, labor inputs as great as 930 h/ha were required to bring the crop to harvest free of weeds, whereas labor inputs of 7 to 17 h/ha removed all surviving weeds when effective weed management systems had been applied.

Genetic and environmental variation of gum content in barley

Abstract: The influence of genetic vs environmental factors on the gum content of the barley grain has been studied by growing 4 varieties of barley, at 4 locations in the South of Spain, with 6 sowing dates at each location. The genetic factors proved to be the more important, accounting for 89% of the variation over locations and 71·5% of the variation among locations and sowing dates. Of the environmental factors studied, the sowing date was the most important. The variety × sowing date interaction was also statistically significant. Furthermore, the later the sowing date the higher the gum content of the grain. There was no variety × location interaction and, therefore, the varieties ranked in the same order at each location. It was also demonstrated that there was a different pattern of response for the varieties when grown in environments which were able to induce high or low gum content, suggesting that low gum content-low response varieties should be grown if the grain is to be used as an adjunct in brewing.

Compositions containing and methods of use of an infectivity-cured hr plasmid-bearing microorganism

Abstract: A novel agriculturally useful composition that includes a seed treated with a selected infectivity-cured Hr plasmid-bearing microorganism. Also provided are methods of enhancing root elongation, shoot elongation or root development of selected seeds. These methods include treating a selected seed with the infectivity-cured Hr plasmid-bearing microorganism. In addition, there is provided a method of inducing germination of grass seed that involves treating a grass seed such as Kentucky bluegrass seed with a selected infectivity-cured Hr plasmid-bearing microorganism. Furthermore, there is provided a method of promoting plant growth at a lower soil temperature than is common at the time of planting a seed of the plant. Additionally, there is disclosed an inoculant for increasing nodulation, root mass and shoot mass in a leguminous plant. The inoculant contains a Rhizobium microorganism and a selected infectivity-cured HR plasmid-bearing microorganism. Also, there is provided an agriculturally useful composition containing a suitable seed treated with this inoculant.

The effect of Rhizobium inoculation on white clover in improved hill soils in the United Kingdom

Abstract: The benefits to establishment and growth of white clover cvs Aberystwyth S.184 and Grasslands Huia of inoculation with three strains of Rhizobium trifolii, using the peat or liquid inoculum techniques, were investigated during 1975–8 on improved hill soils ranging from brown earth through dry and wet peaty podzol to deep peat.Inoculation induced positive response in either number of seedlings, plant cover or dry-matter production in 18 out of 139 comparisons, had no effect in 118 and produced a negative response in three. Most of the positive responses to inoculation were at sites with wet peaty podzol or deep peat soils but of the five sites where increase in clover D.M. production was found in the first harvest year one was a brown earth. The positive agronomic responses occurred only when the proportion of plants with nodules was high and where a substantial proportion ( > 50%) of the latter contained introduced Rhizobium strains at least in the year of sowing. The three negative responses were in numbers of seedlings on one brown earth and two dry peaty podzol soils and with the Huia cultivar only. Despite lack of statistical significance at individual sites the dominant overall trend was for inoculation to enhance seedling establishment and the early growtli of white clover in all soil types.On one brown earth and one dry peaty podzol soil there was some evidence that spraying the Rhizobium on to emerging white clover seedlings was more beneficial, atleast in microbiological terms, than the customary peat inoculum procedure.The incorporation of even a small amount of nitrogen (30 kg/ha) into the seed bed at the time of sowing adversely affected germination, establishment and growth of white clover in some soils. Sometimes the effects of this nitrogen persisted into the first harvest year.

Restricting losses of aerially sown seed due to seed-harvesting ants

Abstract: Seed-harvesting ants occur throughout Australia The main species are Monomorium, Meranoplus, Chelaner, Iridomyrmex, Chalcoponera and Pheidole, the last being the most widespread These ants become economically important only when they take seeds of aerially-sown pasture species If conditions remain dry after sowing the ants can collect large quantities of seed and thus reduce establishment

Effect of penetration resistance on emergence and early growth of silage corn in a laboratory experiment with sandy soil

Abstract: The emergence and early growth responses of silage corn (Zea mays L.) seeds, planted at various depths, to increasing penetration resistance for two soil moisture regimes was evaluated in a laboratory experiment with sandy soil. At soil moisture content levels of 15% and 25% (v/v) increasing penetration resistance below and beside the planting slot linearly increased the time lapse between planting and emergence of 50% of the number of seeds planted. Percentage of emerged seedlings, increase in plant height and dry matter yield during early growth decreased linearly with increasing penetration resistance. For the latter two parameters an increase in soil moisture content from 15% to 25% (v/v) raised the level of the response curves, but the slopes remained practically the same. Under the experimental conditions deeper planting slightly delayed emergence and increased plant height, but dry matter yield was not affected.

The management of Brassica for winter forage in the sub‐tropics

Abstract: In subtropical latitudes temperate crops can be grown during the cool months but the growing season is restricted by the termination and beginning of hot weather. Postponing sowing date in south Florida from October to November to January resulted in 150, 130 and 110-d growing seasons respectively. Dry matter (DM) yields of turnip, swede, rape and kale were lowered by each later sowing date and shorter growing season, and crude protein (CP) concentration was the same as for, or was increased by late sowing. In vitro organic matter digestibility (IVOMD) of turnip, swede and rape leaves was not affected by sowing date, but roots of turnip and swede from the earlier sowings and longer growing seasons were more digestible. Yield of the four species depended on harvest management as well as date of sowing and length of growing season. Total yield of turnip and swede were unaffected by harvest management but multiple cutting resulted in greater leaf yields and smaller root yields, whereas stockpiling resulted in smaller leaf yields and larger root yields. Kale produced more DM when harvested once at the end of the winter growing season but rape produced the greatest DM yield when sown in October and harvested