Showing papers on "Sowing published in 1990"

Concepts and Technologies of Selected Seed Treatments

Abstract: Seed treatments are used on many crop seeds for a variety of purposes. The greatest use of seed treatments has been to provide an inexpensive insurance against rotting of planted seeds by soil fungi such as Pythium spp. and Rhizoctonia solani. Seed treatments for many other purposes are being de­ veloped and used. Increasingly, commercial seed treaters are beginning to view seed treatments as a means to substantially increase the value of the seed and to improve plant growth and productivity. Examples of other types of seed treatments are: (a) treatment with systemic chemicals that can translocate into the seed to control deep-seated plant pathogens. Several chemicals also translocate to the above-ground portions of the seedling and protect against foliar diseases; (b) treatment with microor­ ganisms that can proliferate on the seed, transfer to the root and fix N2, enhance uptake of nutrients, protect the subterranean plant portions against attack by soil-inhabiting fungi, and/or increase plant growth; (c) physical treatments that control seedbome pathogens; (d) seed coatings or pellets that can improve seed shape for planting or provide other benefits; (e) physiolog­ ical seed treatments that enhance germination rate and plant performance; and (j) various treatments that affect seed moistUre relationships and result in improved seed storability or performance.

Genotype, sowing date and plant spacing influence on high-yielding irrigated wheat in southern New South Wales. II. Growth, yield and nitrogen use

Abstract: Sowing date, sowing rate and row spacing effects were studied on irrigated wheat crops at Griffith, N.S.W. during 1983-85 using genotypes differing in maturity, stature and genetic background. The aim was to identify better management practices and genotypes through a better understanding of development and growth of wheat grown under high-yielding conditions. Maximum yield was up to 891 g/m2. The average yield reduction was 50 g/m2 or 6% per 1-week delay in anthesis after 1 October, but varied between 2 and 23%, depending on the season. Lodging was a significant problem in all three years, with less lodging for later sowing dates, earlier maturity types or shorter stature. Plant spacing, through variations in row spacing (17-45 cm) or sowing rate (50-200 kg/ha) did not significantly affect grain yields, but lodging was reduced by increased row spacing and reduced sowing rate. Dry weight at anthesis (600-1 500 g/m2) explained 65% of the variation in lodging, with severe lodging risks for weights over 900 g/m2. Harvest index improved with later sowing or earlier maturity and was, among genotypes within a sowing, negatively correlated with anthesis date, height, lodging score and final leaf number on the main stem. Nitrogen uptake usually ceased before anthesis. Genotypic differences in grain protein concentrations of more than 2% were found. Some genotypes combined high yield with high grain protein concentration (e.g. 717 g/m2, 14.1% protein). Significant genotype effects on spike density, kernel weight, kernel growth rate, and number of kernels per m2, per spike and per g chaff weight were identified, but none seemed to restrict yield. There was much compensation between traits. For example, high kernel numbers (per g chaff, spike or m2) were associated with low kernel weights and vice versa, both within and between genotypes. It was concluded that short-stature, early-maturing, low spike-bearing cultivars are most suited to high-yielding conditions from any sowing date, provided flowering occurs after late September, as such crops have a reduced lodging risk and use assimilates and N most efficiently. Genotypes were highly adaptable and many morphogenetic traits differed widely between genotypes, but were usually similar among dwarf or semidwarf, and among early or late maturing genotypes.

Alysimeter study of the effects of a ryegrass catch crop, during a winter wheat/maize rotation, on nitrate leaching and on the following crop

Abstract: SUMMARY The effects of an intercrop catch crop (Italian ryegrass) on (i) the amounts and concentrations of nitrate leached during the autumn and winter intercrop period, and (ii) the following crop, were examined in a lysimeter experiment and compared with that from a bare fallow treatment. The catch crop was grown in a winter wheat/maize rotation, after harvest of the wheat, and incorporated into the soil before sowing the maize. A calcium and potassium nitrate fertilizer labelled with 15N (200 kg N ha−1; 9.35 atom per cent excess) was applied to the winter wheat in spring. Total N uptake by the winter wheat was 154 kg ha−1 and the recovery of fertilizer-derived N (labelled with 15N) was 60%. The catch crop (grown without further addition of N) yielded 3.8t ha−1 herbage dry matter, containing 43 kg N ha−1, of which 4.1 % was derived from the 15N-labelled fertilizer. Two-hundred kg unlabelled N ha−1 was applied to the maize crop. During the intercrop period the nitrate concentration in water draining from the bare fallow lysimeters reached 68 mg N1−1, with an average of 40 mg N1−1. With the catch crop, it declined rapidly, from 41 mg N I−1 to 0.25 mg N I−1, at the end of ryegrass growth. Over this period, 110 kg N ha−1 was leached under bare fallow, compared with 40 kg N ha−1 under the catch crop. 15N-labelled nitrate was detected in the first drainage water collected in autumn, 5 months after the spring application. The quantity of fertilizer-N that was leached during this winter period was greater under bare fallow (18.7% of applied N) than when a catch crop was grown (7.1 %). In both treatments, labelled fertilizer-N contributed about 34% of the total N lost during this period. With the ryegrass catch crop incorporated at the time of seedbed preparation in spring, the subsequent maize grain-yield was lowered by an average of 13%. Total N-uptake by the maize sown following bare fallow was 224 kg N ha−1, compared with 180 kg ha−1 with prior incorporation of ryegrass; the corresponding values for uptake of residual labelled N were 3% (bare fallow) and 2% (ryegrass) of the initial application. Following the maize harvest, where ryegrass was incorporated, 22.7% of the previous year's labelled fertilizer addition was present in an organic form on the top 30 cm of lysimeter soil. This compares with 15.7% for the bare fallow intercropping treatment. Tracer analyses showed overall recoveries of labelled N of 91.7% for the winter wheat/ ryegrass/maize rotation and 97% for the winter wheat/bare fallow/maize rotation. The study clearly demonstrated the ecological importance of a catch crop in reducing N-leaching as well as its efficient use of fertilizer in the plant-soil system from this particular rotation. However, the fate of the organic N in the ploughed-down catch crop is uncertain and problems were encountered in establishing the next crop of maize.

Mechanical and cultural weed control in corn and soybeans

Abstract: Many farmers and consumers are reevaluating chemical weed control because of the environmental risks of herbicides and their influence on farm size and diversity. This paper reviews research of the last 35 years on mechanical and cultural weed control in corn (Zea mays L.) and soybeans (Glycine max L.). Soybeans can better use the weed control advantages of late planting and narrow row spacing and are less affected by early stand losses from mechanical weed control. In Minnesota, delaying planting to early June allows early germinating weeds to be controlled by preplant tillage but reduces the maximum yield potential of corn by approximately 25 percent and soybeans by approximately 10 percent. Narrow rows allow the crop canopy to close earlier, preventing emerging weeds from developing. However, in a nonchemical weed control system, the row spacing should allow for inter-row cultivation to control weeds that emerge with the crop. Up to a 10 percent reduction in crop stand may be expected in fields that have been rotary hoed. In Minnesota, a 10 percent stand loss results in a 2 percent loss of corn yield potential and no loss of soybean yield potential. Successful mechanical weed control is directly related to the timeliness of the operation. Rotary hoeing is effective on weeds that have germinated but not yet emerged but not on weeds that germinate from deeper than 5 cm, on no-till fields, or on fields with more than 20 to 30 percent crop residue. Inter-row cultivation is most effective on weeds up to 10 to 15 cm tall. Successful nonchemical weed control requires highly refined management skills and is as much an art as a science.

Seed priming influence on germination and emergence of pepper seed lots

Abstract: The seed lots that were slower to germinate had a greater response to priming, resulting in a linear relationship between the initial mean time to germination or mean time to emergence and the reduction in MTG or MTE resulting from priming. Seed priming was a simple and effective means of shortening the time from sowing to emergence of direct-seeded pepper plantings

Corn Response to Rye Cover Crop Management and Spring Tillage Systems

Abstract: The use of a winter rye (Secale cereale L.) corn (Zea mays L.) doable cropping sequence in combination with appropriate tillage practices could increase biomass production and reduce soil erosion potential in southern Ontario. A 3-yr study (1982–1984) was conducted at two locations to determine the potential of this sequence for double cropping, and to evaluate spring tillage systems and management of the rye residue on subsequent productivity of corn. Winter rye was planted in early October after corn silage harvest, and either chemically killed or harvested as silage in the spring before corn planting. Rye treatments consisted of no rye, rye harvested in the spring and rye residue left on the plots. Spring cultivation treatments were no-till, tandem discing, and mold board plowing followed by secondary tillage. The use of a winter rye cover crop delayed corn development and reduced corn biomass yield by 11% at the Elora location and by 17% at the Woodstock location. The adverse effect of the rye crop was more pronounced under no-till than where the soil was tilled. Removal or retention of the rye residue had no consistent effect on the subsequent corn crop. An allelopathic effect resulting from the rye crop may be one plausible explanation for the reduction in corn yield. Total biomass yield (rye + corn) was increased relative to corn alone, if the soil was cultivated. Therefore, a winter rye-corn sequence may still be of interest, despite a reduction in corn yield, especially if advantages such as total biomass production and the potential for decreased soil erosion during fall and winter are considered. Research supported by Agriculture Canada (ERDAF).

Photocontrol of Weeds Without Herbicides

Abstract: (...) On the basis of 7 years of experience it is proposed to do the last harrowing before sowing or planting, and also these, during the time span between 1 h after sunset and 1 h before sunrise to lessen considerably the emerging weeds in crop fields. Further tillage should be carried out during bright daylight to photostimulate the germination of the weed seeds, and to diminish equivalently their seed bank. This method should allow the restriction of the herbicide load worldwide

Effects of field beans, fallow, lupins, oats, oilseed rape, peas, ryegrass, sunflowers and wheat on nitrogen residues in the soil and on the growth of a subsequent wheat crop

Abstract: The effects on a winter wheat test crop of a preliminary year of winter or spring field beans (Vicia faba), winter oats, winter oilseed rape, winter or spring peas (Pisum sativum), winter wheat, spring lupins (Lupinus albus), spring sunflowers (Helianthus annuus) or a cultivated fallow were compared in three 2-year experiments on clay-with-flints soil at Rothamsted from 1986 to 1989. In one experiment, autumn-sown ryegrass (Lolium perenne) and an uncultivated fallow, given weedkiller, were also included in the first year. Plots of test-crop wheat were divided to compare no N fertilizer with an optimal amount estimated from a predictive model.Amounts of take-all (Gaeumannomyces graminis) in the test crop of wheat following wheat were very slight in the first experiment, but large in the second and third. All the break crops reduced takeall to none or very slight amounts.Amounts of NO3-N in the soil in autumn after the first-year crops ranged from 7 to 95 kg N/ha. On average, they were least after oats, and most after cultivated fallow. In autumn 1988they were least after autumn-sown ryegrass. In early spring, amounts of NO3-N were generally less, ranging from 7 to 55 kg N/ha, depending on preceding crops, sowing date of the wheat and the weather. Amounts of NH4-N in soil were little affected by preceding crops or weather and were generally smaller in spring.The estimated average N fertilizer requirement of test-crop wheat following winter wheat was 230kg N/ha. This was increased by 10 kg N/ha following winter oats, decreased by 40 kg N/ha after spring peas and by 30 kg N/ha after winter rape, winter peas, spring beans and cultivated fallow. Other preliminary crops not represented every year had effects within this range.Grain yields of test-crop wheat given optimal N averaged 7·2 t/ha after winter wheat, c.1·5 t/ha less than the average after most of the break crops. The yield after oats was limited by self-sown ‘volunteers’ and that after ryegrass by limited soil N after ploughing.Of the break crops tested, winter and spring beans, winter oats, winter rape and spring peas all gave satisfactory yields. A farmer should choose between these on the basis of local farm circumstances and current economics of the break crops. Differences between effects on take-all and savings on fertilizer N were too small to influence this decision.

Cover crop and herbicide influence on row crop seedling establishment in no-tillage culture.

Abstract: The establishment and management of nine cover crops in Kentucky production systems were evaluated in field experiments over a 2.yr period. 'Wheeler' rye, 'Barsoy' barley, and 'Tyler' wheat cereal grains produced greater biomass (180 to 260 g/m2) than the pasture species tall fescue, creeping red fescue, and white clover (55 to 110 g/m2). 'Kentucky 31' tall fescue, creeping red fescue, and white clover proved most difficult to control, and significant regrowth occurred regardless of herbicide or rate applied. HOE-39866 (1.7 kg ai/ha) was effective in rapidly controlling all cover crops except tall fescue by 30 days after application. Sethoxydim and fluazifop (0.4 and 0.3 kg ai/ha, respec- tively) effectively controlled the cereals and two ryegrass species. Glyphosate applied at 1.1 and 2.2 kg ai/ha was also effective, while 0.6 kg ai/ha controlled only cereal grain growth adequately. After chemical control, pasture grass plots contained fewest weeds/m2 with some reduc- tions likely due to density and regrowth of the sods. Cover crops were effective in suppressing weed growth at 45 days after chemical control. However, significant weed growth existed in all cover crop plots by 60 days after kill. Row crop establishment increased linearly with increasing glyphosate rate. Cereal grain covers provided the most compatible planting situations for greatest seedling estab- lishment, with rye and wheat providing greatest weed suppression. Generally, increased weed suppression pro- vided by a cover crop was accompanied by reduced row crop establishment, with greatest reductions observed in pasture grass plots. Cucumber was most easily established while snap pea was most difficult. Nomenclature: Fluazi- fop, (?)-2-(4-((5-(trifluoromethyl)-2-pyridinylloxy)phen- oxy)propanoic acid; HOE-39866, the ammonium salt of DL-homoalanin-4-yl-methyl phosphinic acid; glyphosate, N-(phosphonomethyl)glycine; sethoxydim, 2-(1-(ethoxyim- ino)butyl - 5 - (2-(ethylthio)propyl) - 3 - hydroxy - 2 - cyc- lohexen-l-one; tall fescue, Festuca arundinacea Schreb. 'Kentucky 31'; creeping red fescue, Festuca rubra L. ssp. commutata; Dutch white clover, Trifolium repens L.; cucumber, Cucumis sativus var. sativus 'Calypso'; snap pea, Pisum sativa L. 'Sparkle'; rye, Secale cereale L. 'Wheeler'; winter wheat, Triticum aestivum L. 'Tyler'. Additional index words. Minimum tillage, germination, glyphosate, sethoxydim, fluazifop, HOE-39866, row crop.

Prospects for Brassica carinata as an oilseed crop in India.

Abstract: Twenty one strains of Brassica carinata were tested under irrigated, rainfed and saline soil conditions and five strains under late sowing conditions along with five varieties each of B. juncea, B. napus and B. campestris var. yellow sarson, brown sarson and toria. Brassica juncea had the largest seed and oil yield under irrigated conditions but B. carinata performed much better than other species under late sowing, rainfed and saline soil conditions.

Genotype, sowing date and plant spacing influence on high-yielding irrigated wheat in southern New South Wales. III. Potential yields and optimum flowering dates

Abstract: Experiments were undertaken at Griffith, N.S.W., using a range of genotypes, sowing dates and plant spacing to identify management strategies and genotypes that would increase irrigated wheat yields and minimize lodging risk. Results are used in this paper in an analysis of potential yield and optimum anthesis date, as influenced by temperature, irradiance, sowing date and genotype. Lodging duration was used to predict potential yields in absence of lodging from the lodgingaffected yields in the study. Lodging duration between 7 days after mid-anthesis and maturity was found to best explain early and late lodging effects on yield. Yield reductions due to lodging were up to 45%. Predicted potential yields (Y,) were 800-950 gIm2 and the end of the optimum anthesis period varied from year to year. Average temperature (T, "C) and total irradiance (ZR, MJ/m2) for a preanthesis period of 500°C days (>3"C) or a maximum of 60 days explained 61% of the variation in Y,: Yp=981 - 53.4T+ 0.51 ZR (g/m2). Using historical weather data and frost risk restrictions indicated an optimum anthesis period between 22 September and I0 October when average predicted yields were reasonably stable. Flowering after mid-October caused reductions in average predicted yield of 70 g/m2 or 1 1 % per I-week delay in anthesis. Kernel weights decreased by 5% per 1°C above 14"C, but this decrease was also associated with increased kernel numbers. High-yields under irrigation can only be achieved consistently and efficiently with lodging resistant (short, stiff stems) or avoiding (early maturing) genotypes. Very early maturing types for late sowing dates are currently not commercially available. Adjusted management practices (e.g. relatively late sowing) and lower target yields are recommended for current lodging susceptible varieties.

Genotype, sowing date and plant spacing influence on high-yielding irrigated wheat in southern New South Wales. I. Phasic development, canopy growth and spike production

Abstract: Sowing date, sowing rate and row spacing effects were studied on high input crops at Griffith, N.S.W., between 1983 and 1985 using 25 bread wheats (Triticum aestivum L.) and 3 triticales (X Triticosecale Wittmack). The aim was to identify improved management practices and genotypes through a better understanding of development and growth of irrigated wheat grown under high-yielding conditions. The genotypes were chosen to represent a wide range in genetic background, maturity and stature. Growing period durations were between 208 days and 100 days for early April and mid-August sowings, respectively, with differences in anthesis dates within sowing dates of up to 45 days. Genotypes were classified into six major maturity groups. There was no maturity type that could flower close to 1 October from a wide range of sowing dates since anthesis was delayed by 0.3 to 0.5 days per 1-day delay in sowing. Increased daylength sensitivity tended to delay anthesis relative to the timing of floral initiation and terminal spikelet formation. The end of tillering was generally associated with the attainment of 50-60% light interception rather than a given development stage of the inflorescence. Spike density was not closely related to maximum tiller number but depended on genotype, environment and plant density. Leaf appearance rate was influenced by environment and genotype, but was independent of spike development. For a given final leaf number, internode elongation started at a later leaf number for later sowing dates, resulting in reductions in both node number and height. Crop height decreased by up to 5 cm per 1-week delay in anthesis date. The period of full light interception decreased from 133 days to 43 days between April and August sowings, respectively. The timing of reproductive development determined the green area duration, but the initial development and size of the canopy was less affected by it, because of adjustments in number and type of tillers, and size and thickness of leaves. The development and maintenance of an adequate canopy was not restricted by earliness, shortness or low sowing rates (50 kg seed/ha) for April-July sowing dates.

Yield advantage of two semi-dwarf compared with two tall wheats depends on sowing time

Abstract: Slow adoption by farmers in Western Australia of new wheat cultivars led us to propose that their grain yield advantage over the old cultivars may not be evident under the traditional agronomic practices used in the State. The experiments, including both tall (rht) and semi-dwarf (Rht) commercial cultivars, were sown from early to mid-May, up to early July at five locations each year in the central wheatbelt of southwestern Australia in 1986, 1987 and 1988. Semi-dwarf outyielded tall cultivars more when sown in May (0.65 t ha-l) than in early June (0.35 t ha-1) and did not outyield them at later sowings. It is postulated that the yield advantage of the semidwarfs is dependent on early sowing. The yield advantage of the semi-dwarfs was related to greater ear and kernel numbers. The relative reduction in kernel size with later sowing was greater in the semi-dwarfs than in the tall cultivars. The semi-dwarfs had larger harvest indices at the May sowings but the talk equalled or exceeded them at the sowings in June. We concluded that the semi-dwarfs used in our experiments were more sensitive to the stresses associated with later sowing in this environment than the tall cultivars. The optimum flowering period for the study area over the three seasons was 7 to 29 September. However, there was considerable variation from season to season, and we concluded that an adequate definition of the optimum flowering period should be based on time-of-sowing experiments over a range of seasons.

Effect of supplementary irrigation during reproductive growth on winter and spring chickpea (Cicer arietinum) in a Mediterranean environment.

Abstract: Inadequate soil moisture is one of the main constraints on the productivity of chickpea in the rainfed farming systems of the dry areas in West Asia and North Africa. The response to irrigation at flowering and pod filling of winter- and spring-sown kabuli chickpea was studied in 1983–86 at ICARDA's main research station at Tel Hadya in northern Syria. In 1983/84 when the cultivar ILC3279 was sown in winter, irrigation increased yield by 105% over a crop receiving 229 mm of precipitation. In 1984/85, ILC3279 was sown in winter and spring. Advancing the date of sowing to winter increased yield by 65% and irrigation increased seed yield by 73% in winter and 143% in spring sowings compared with crops grown receiving 373 mm rainfall.In 1985/86, six cultivars (ILC482, ILC3279, FLIP81–57W, FLIP81–293C, FLIP84–19C and FLIP84–80C) were compared, but differences in their response to irrigation were negligible. Advancing sowing from spring to winter increased seed yield by an average of 66%. Irrigation increased seed yield in winter and spring sowings by 56% and 72%, respectively, over those receiving 316 mm annual precipitation. Irrigation is, therefore, a way of increasing the productivity and yield stability of chickpea in northern Syria but the improvement in yield depends on the total rainfall and its distribution over the growing season.

Rooting depth of wheat in the Victorian Mallee

Abstract: In 1986 and 1987 wheat was sown in an experiment at the Mallee Research Station, Walpeup, at 2 times of sowing and with 3 rates of applied nitrogen. Soil cores were taken and trenches excavated to 1.5 m to measure wheat root growth and depth of rooting. Wheat roots penetrated to a maximum depth of 104 cm in crops sown in May, the optimum time of sowing for maximum yield, while delayed sowing reduced total root biomass and limited rooting depth to 73-83 cm. The application of nitrogen fertiliser did not affect either the rooting depth or growth and yield. Significant changes in total soil water content between sowing and harvest only occurred in 1987 with the early and late sown crops reducing the total soil water content by 47 and 99 mm respectively. In 1986, above average rainfall during the growing season caused the early sown crop to accumulate more water below 50 cm than the late sown crop. While total water use was increased only in 1986 with early sowing, crop water use efficiency and yield was greater in both years. The addition of nitrogen had no effect on crop water use or water use efficiency. A survey of wheat crops carried out in 1988 on 10 Mallee farms also found that shallow rooting is widespead. The field experiment and survey data show that, irrespective of sowing time, roots did not penetrate as far down the profile as might be expected, given reported rooting depths commonly in excess of 200 cm on similarly textured soils. This was shown to be associated with high soil pH and salt content. Poor rooting depth of wheat in this environment will restrict the use of stored water and accordingly, calls the practice of fallowing into question.

Consumption of wheat seed reserves during germination and early growth as affected by soil water potential

Abstract: Seed size and weight are important criteria for determining seedling vigour and stand establishment. Evolution of seed dry weight of wheat (Triticum aestivum L.) during germination and early growth was examined because poor stands are often associated with the depletion and exhaustion of seed reserves. Two laboratory experiments were conducted on filter paper and in soil at three water potentials using wheat seeds. Seed, root, and shoot dry weights were recorded at approximately one-day intervals. Coleoptile and first leaf lengths were also measured at all sampling periods. Wheat seedlings grown on filter paper in the dark grew to a length of 90 to 100 mm with 50% of the initial seed weight remaining after eight days when the experiment was terminated. In soil, wheat seedlings grew 15 mm with 25% of the initial seed weight remaining. Seed reserves were depleted more quickly when the soil was wet because seedlings grew more quickly. There were significant and similar negative relationships between seed weight and coleoptile length of wheat seedlings grown on filter paper and in soil. There was no effect of soil water potential on the relationship between seed weight and shoot length. Therefore, it was concluded that poor wheat stands are not likely to occur due to depletion of seed reserves under field conditions without mechanical obstacles.

Effect of seed weight, and seed phosphorus and nitrogen concentrations on the early growth of wheat seedlings.

Abstract: Wheat seeds of uniform weight selected from 3 batches of seed with phosphorus (P) concentrations of 0.14, 0.17 and 0.19% were sown in soil with a range of applied P treatments. Seedling emergence was more rapid the higher the seed P. By 25 days after sowing all plants grown at the highest concentration of applied P were similar in size, but with lower applied P, plants from seed with higher P concentrations had an advantage. A range of weight classes was selected from 2 batches of seed raised at low or high concentrations of P. There were 11 groups ranging in mean seed weight from 28 to 58 mg and in seed P from 0.13 to 0.37%. Seedlings from the high P batch had larger first leaves, a higher dry weight, and longer roots than those from the low P batch when grown in a highly P-deficient sand culture system. Within each batch, heavier seeds produced larger leaves, heavier plants and longer roots. The yield differences between batches were largely accounted for if the seed P content (¦g P/seed) was considered rather than either percentage P or seed weight alone. Differences in seed nitrogen concentration or content did not consistently account for differences in seedling growth.

Planting date and nitrogen rate effects on spring malting barley.

Abstract: (...) This study was conducted to determine planting date and N rate effects on grain yield, grain protein, kernel plumpness and yield components of spring malting barley grown under a production system that minimized crop water stress. Between 1984 and 1988, Klages' barley was planted at 2-wk intervals between 15 April and 19 May (expressed as days from 1 January) at Powell, WY on a Garland clay loam. Ammonium nitrate was applied at rates of 0, 67, 134, and 202 kg N ha -1 (...)

Photocontrol of weeds without herbicides

Abstract: (...) On the basis of 7 years of experience it is proposed to do the last harrowing before sowing or planting, and also these, during the time span between 1 h after sunset and 1 h before sunrise to lessen considerably the emerging weeds in crop fields. Further tillage should be carried out during bright daylight to photostimulate the germination of the weed seeds, and to diminish equivalently their seed bank. This method should allow the restriction of the herbicide load worldwide

The effect of N placement on grass weeds and winter wheat responses in three tillage systems

Abstract: Field studies were conducted for three seasons (1978–1979, 1979–1980 and 1981–1982) on a Palouse silt loam near Pullman, Washington, to compare the effects of broadcast and deep banding of nitrogen (N) fertilizer beneath winter wheat (Triticum aestivum L.) seed on N uptake and dry matter production of downy brome (Bromus tectorum L.) and jointed goatgrass (Aegilops cylindrica Host.), and on N uptake, dry matter production and grain yields of winter wheat. Three tillage systems were used: conventional tillage; shallow roto-tilling, or no-tillage prior to planting. Rates of N were 0, 65, 130 and 190 kg N ha−1 as ammonium nitrate. Additional plots were maintained free of weeds at the 130 kg N ha−1 rate. In 1983–1984, deep banding of the fertilizer between rows in a paired-row configuration was compared to surface-broadcast N fertilizer using N rates of 0, 45, 90 and 135 kg N ha−1. There were no significant differences between broadcast and deep-band application of N on grass weed N uptake or dry matter production with mold-board plowed or no-tillage, but there was greater weed growth with surface-broadcast N with shallow roto-tilling. Wheat N uptake, growth and grain yields were consistently higher with band-applied N compared to broadcast N. The yield response to banding N was the same with or without the presence of grass weeds.

Seed Size/Shape and Tillage System Effect on Corn Growth and Grain Yield

Abstract: This research was conducted to evaluate the effects of corn (Zea mays L.) seed size/shape on field performance of commercially available corn hybrids under conventional tillage (CT) and no-tillage (NT). Field studies were conducted in 1987 and 1988 under the two tillage systems with small-round, small-flat, large-round, and large-flat seed of hybrids LH74×LH51 and A632×LH39, on Plano silt loam (fine, mixed, mesic Typic Argiudoll) soil at Arlington and Janesville, WI. At Arlington, there were also early (mid- to late-April) and late (mid- to late-May) planting dates

Planting Method and Irrigation Rate Influence Vegetative and Reproductive Growth of Peach Planted at High Density

Abstract: Several planting treatments modified vegetative and reproductive growth of young, own-rooted peach (Prums persica) trees evaluated at two levels of irrigation in a high-density orchard (5000 trees/ha). Trees planted in auger holes, narrow herbicide strips, and in fabric-lined trenches, but not those from raised beds, were smaller than control trees set in holes dug with a shovel. After two growing seasons, trees planted in the fabric-lined trenches were smaller and had more flowers per node and greater flower bud densities than trees in other planting treatments. Yield efficiency was greatest for this treatment, although fruit size was small throughout the orchard. Irrigation rates did not affect fruit yield or size. The effects of irrigation rate on vegetative growth were small compared to differences among planting treatments. Controlling vigor of fruit trees has been a major goal of pom- ologists for centuries. Achieving a proper balance between veg- etative and reproductive growth is necessary to enhance production early in the orchard's life and to maximize yields during the entire life of the orchard. Commercially acceptable dwarfing rootstock for peach in the southeastern United States have not been identified. Summer pruning and various growth-regulating compounds have offered some suppression of vigor, yet these practices can be costly and often have adverse side effects. Root restriction of hydroponically grown peach seedlings re- sulted in less root and shoot growth with a root : shoot ratio similar to non-restricte d plants (Richards and Rowe, 1977). Cockroft and Wallbrink (1966) reported that peach tree vigor was related to the volume of soil readily accessible to the root system.

Placing superphosphate at different depths in the soil changes its effectiveness for wheat and lupin production

Abstract: In a field experiment on a sandplain soil in a low rainfall (326mm per annum) Mediterranean environment of south-western Australia, seven levels of single superphosphate, 0, 7.5, 10, 14, 19.5, 30 and 39 kg P ha−1, were placed at either 3, 5, 7, 9, 11 or 13 cm depth before sowing wheat (Triticum aestivum) at 3 cm. In a separate treatment, superphosphate was drilled with the seed (the normal practice). In the second year, the plots were sown with lupins (Lupinus angustifolius) at 3 cm depth with no additional superphosphate. In three separate treatments, superphosphate at 0, 14 and 39 kg P ha−1, was drilled with the lupin seed (the normal practice) on plots that had received no superphosphate in the first year. Yields of wheat and lupins were used as a measure of the effectiveness of the superphosphate placement treatments relative to the effectiveness of superphosphate drilled with seed of wheat (year 1) or lupins (year 2), to give relative effectiveness (RE) values in each of the two years.

Increasing phosphorus concentration in seed of annual pasture legume species increases herbage and seed yields

Abstract: In glasshouse experiments with low levels of soil applied phosphorus (P), yields of four annual pasture legumes (Medicago polymorpha, Trifolium subterraneum, T. balansae, Ornithopus compressus) increased with increasing P concentration in the seed. In a further experiment, M. polymorpha cv. Serena was grown at the same plant density from seed of two P concentrations and two seed sizes when two levels of finely ground superphosphate were applied to the soil. Higher P concentrations in the seed increased yields of dried tops by about 30% for the first harvest (21 days), 20% for the second harvest (52 days), and 9% at maturity (103 days), and seed yields by 11%. Larger seeds increased yields of dried tops by between 6–46% for the first two harvests but at maturity yields of dried tops and seed were unaffected by seed size. None of the interactions were statistically significant (P>0.05), except for the first harvest when two interactions (P concentration in the seed × seed size (i.e. P content in seed), and P applied to the soil × P concentration in the seed × seed size) were significant at P<0.05 level. In a field experiment, Trifolium subterraneum clover seed (two cultivars) of the same size but with two different P concentrations was sown at the same plant density and two levels of granulated (0.2–5 mm) superphosphate were applied to the soil surface. The higher level of superphosphate increased dried herbage yields of the dense clover swards by three- to four-fold 90 and 120 days after sowing. The higher P concentration in the seed increased yields of dried herbage by between 50 to 25%, depending on the level of P applied to the soil and the harvest date.

Phosphorus concentration in barley (Hordeum vulgare L.) seed: Influence on seedling growth and dry matter production

Abstract: The effect of phosphorus (P) concentration in barley seed on seedling growth has not been much investigated. Consequently, two experiments were conducted in the greenhouse to determine the effect of P concentration in barley seed (Hordeum vulgare L., cv. Empress) on the seedlings grown in sand-filled boxes receiving a culture solution without P. Seeds were selected with three P concentrations: high-P (113.0 mmol P kg−1), medium-P (80.7 mmol P kg−1) and low-P (54.9 mmol P kg−1). At 21 days after sowing, the shoot and root yield or shoot height was the least with seedlings from low-P seed. In the other experiment, high-P and low-P seeds were wetted with distilled water or with a solution of 25.8 cmol L−1 of NaH2PO4 for 24 h, and then grown for 31 days. Solution P had been imbibed by seeds whether low or high in native P, but only the imbibed P held by low native P seed benefited seedling dry matter accumulation and shoot elongation. The lack of benefit from seed-imbibed P on seedlings grown from high-P barley seed was associated with low recovery of the imbibed P in those seedlings.

Establishment of Ammophila arenaria (marram grass) from culms, seeds and rhizomes.

Abstract: (1) A study was made of three different methods of establishing Ammophila arenaria: planting bundles of culms (the traditional method), sowing seeds, and disc-harrowing rhizomes. The effects of applying slow-release fertilizer were also examined. (2) A preliminary experiment examined the relative effects of straw, carboxy methyl cellulose, compost, reed, and a mixture of crop species in stabilising the sand. Only straw was effective. (3) Sowing seeds at 200, 400, and 600 m-2 and rhizomes (fragments 15 cm long, each with at least two buds) at 20, 40, and 60 pieces m-2, showed that higher rates resulted in higher numbers of seedlings and primary shoots. However, after one growing season, production of biomass and tillers was only increased by fertilization. (4) Although the recovery in above-ground plant parts of N and P was fairly low, slowrelease NPK fertilizer (80-20-20 kg ha-1) increased biomass significantly. Fertilizing rhizomes with 160-40-40 kg NPK haproduced significantly more dry matter than with 80-20-20 kg NPK ha1, but this had no effect on sown or planted A. arenaria. (5) Rhizomes produced more tillers and biomass than bundles of culms and seedlings when fertilizer was applied. Without fertilizer, culms gave most biomass production, but seedling growth was very poor. (6) A germination experiment in the laboratory showed that a high rate and percentage of germination was obtained at fluctuating temperatures and by supplying light. At fluctuating low temperatures, stratification increased germination of seeds. At fluctuating high temperatures, seeds germinated well and stratification gave no improvement.

Response to sowing time of three contrasting Australian cultivars of oilseed rape ( Brassica napus )

Abstract: Serial sowings of three cultivars of oilseed rape were made from autumn (May) to spring (October) at two sites, one in the north and one in the south of Tasmania, in 1981. The highest seed yields at both sites exceeded 5 t/ha from early sowing, ranging down to c. 2 t/ha from late sowing at a site where irrigation was adequate and to < 1 t/ha where late-sown crops suffered from water stress. The midseason cultivar Marnoo gave the highest yields at both sites, resulting from a combination of substantial (800 g/m2) top growth before flowering, excellent seed survival, a long period for grain filling and high oil content. The early-flowering line RU1 made much less growth before flowering; while this was partly made up for in later growth, nearly as many seeds per pod being retained as in Marnoo, oil content was low. The later-flowering cultivar Wesbell made more growth before flowering than the other cultivars, but when sown early it tended to grow tall, lodge and lose many pods in the dense, tangled canopy. This, combined with generally fewer seeds per pod, resulted in a much less efficient crop in allocation of dry matter to seeds and oil. Wesbell failed to flower uniformly from the late sowings, indicating segregation for vernalization response. The many immature seeds at harvest gave a low overall oil content. All three cultivars responded to vernalization and longer photoperiod in a pot experiment. While photoperiod appeared to be the main factor controlling the development rate to flowering in the field, there were interactions with vernalization response andtemperature.