Showing papers on "Sowing published in 1972"

Cicer L., a monograph of the genus, with special reference to the chickpea (Cicer arietinum L.), its ecology and cultivation

Abstract: 1. The history of the chickpea or gram, Cicer arietinum L., has been described from Homer's time and the earliest finds, 5450 B.C. in Hacilar, Turkey, up to the present day. The crop was first domesticated in Asia Minor and was introduced in India either from Central Asia or Asia Minor, the two main centres of origin. Some forms were even introduced rather recently. Ethiopia is a secondary centre of domestication; connections with Egypt or Asia remain speculative. Several pieces of evidence oppose the opinion of DE CANDOLLE (1882) that the ancient Egyptians and Jews had only known the chickpea for two millenia. Medical uses, no longer widely practised, are discussed. The spread to the present areas of cultivation is described and mapped. 2. The genus Cicer L. has been revised. Popov (1929) accepted 22 species, now 39 species (8 annual, 31 perennial) are known. One species is described for the first time: C. multijugum from Afghanistan. A key to the species is prepared. The species, arranged alphabetically, are described and accompanied by detailed illustrations. The synonymy and typifications are given, as well as notes on geography, ecology and morphology. The geographical distribution of each species of the genus, occurring in Central Asia, Asia Minor and the Medi terranean, is presented in maps. It is stressed that the variability and geography of many species is not known sufficiently. The poor availability of fresh material of the wild species is a handicap to research. The relation to the other genera in Vicieae is discussed. Cicer occupies a somewhat peculiar place with its glandular hairs, inflated fruits and seed shape. The infraspecific classification in the cultivated species is reviewed; an informal classification is presented on base of the work of POPOVA (1937) without rejecting the older varieties distinguished by JAUBERT and SPACH, and ALEFELD. 3. The importance of the chickpea as the third pulse crop in the world after beans and peas is presented in a map, graphs and tables. The crop ranks l5th among all crops in area occupied yearly. Yields, at present an average of about 700 kg per ha, are highest in Egypt (1670 kg) and Turkey (1220 kg). About 83 of the world production is in the Indian subcontinent. The weather is the main reason for fluctuation in area. The partial recession in area, due to the expanding new cereal cultivars, will be met by higher yields per unit area and aided by higher prices. 4. Some anatomical particulars, e.g. the glandular hairs, are shortly reviewed. 5. The chickpea is generally cultivated in a traditional way. The resistance to drought (deep roots) and ability to grow in poor soils has not increased the care of the crop. However, with good soil preparation, proper sowing on rows, cultivation and fertilization the crop can yield reasonably. The sowing date is very important. Sowing early in the growth season is to be preferred, except in case of wilt disease. Plant density, sowing depth and sowing seed are discussed. Irrigations, needed in some countries, should be practised with care so as not to induce soil anaeroby. Often the chickpea is grown mixed with wheat or mustard, against crop failures and for utilization of different soil layers. In rotation the chickpea is a well esteemed crop. It has maintained soil fertility at a certain level for centuries in the densely populated areas of India. The plants are harvested mainly by hand. Threshing machines need good adjustment to prevent breakage of seeds. Storage is an important problem, since much loss may occur. 6. Ecological trials were carried out on light, daylength, temperature and relative humidity. The photosynthesis rate varied from 250-500 μg CO 2 -uptake per cm 2 and per h at about 26°C, but at 18°C, the rate was not much less. Leaves of two-weeks old are the most effective in photosynthesis and may use twice as much CO 2 as the four-week old leaves. Estimated calculated production appeared to be 12-14 tons of total dry matter, or about 5-7 tons of grains, similar to the highest yield ever obtained on a small plot. The chickpea is a quantitative LD plant. Under 16-h days the flowering was advanced by e.g. 20-35 days, if compared with 9-h days. Short days did not prevent flowering. Dry matter yield was improved in LD. The influence of the photoperiodic effect alone of the daylengths following different sowing dates on flowering and yield is small. Increasing photoperiods appeared to be more favourable than decreasing ones. The optimum temperature for early vegetative growth ranges from 21-29°C (night and day) to 24-32°C for different cultivars. Over the entire growth period the optimum temperature is somewhat lower, 18-26°C and 21-29°C, which is also optimum for flowering. The relative humidity was found to have little influence on fruit-setting. A decrease in light intensity of 25 % of the available amount during May and June, however, was found to decrease the number of pods by 25-50%. Data on soils and nutrients are summarized. As yet the chickpea does not respond to dressings of more than 10 kg N and 30 kg P 2 O 5 per ha. Moderately heavy soils are preferred, but both heavy and light soils are used in some areas. Growth substances usually have a negative influence on the growth of chickpeas. Scarcity of practical trials prohibits any recommendation. Topping appears to be an old practice to stimulate branching. Regeneration, however, takes a long time and is only sufficient under optimum conditions and if applied at an early stage. 7. Breeding has not yet improved yields over large areas. A review on cytogenetics is given. Some new reports on the somatic number of chromosomes of some wild species are added. As crossing technique is a delicate operation, hybridization on a large scale is at present not possible, but pollination at an early stage without emasculation may be a solution. The introduction of new cultivars has not been very successful because they have not shown large differ ences with local cultivars. 8. The most important insect pests of the chickpea are the podborer and the pulse beetles, which are described in some detail. Geographical distribution and way of control is given. All reported pests are mentioned. Nematode attacks seem to be underestimated at present. Rats may cause important damage in stores. 9. The diseases of the chickpea, their occurrence, possible way of control are described. Most damage is done by wilt, caused by both a soil fungus and by physiological drought, and blight. Several other diseases such as rust and foot rots are not yet serious over large areas. As for pests, chemical control is often uneconomic. 10. The chickpea is mainly used as human food, whether fresh, boiled, or roasted in many preparations. As a part of balanced foods it can form an important supplement to the protein nutrition of children. The proteins of chickpea constitute an important part of the protein intake in India. The chemical composition of the seeds (e.g. up to nearly 30% of protein) is given, as well as the amounts of essential amino acids. Except sometimes for methionine and for tryptophan the chickpea appears to be an excellent source of amino acids.

Volatile metabolites controlling germination in buried weed seeds.

Abstract: Velvetleaf (Abutilon theophrasti Medic), morning glory (Ipomoea purpurea [L.] Roth), and wild mustard (Brassica kaber [D.C.] L. C. Wheeler) seeds exhibited decreased germination with increased planting depth in soil. Flushing the soil for 2 minutes each day with air overcame the inhibition. A sealed in vitro system was used to sample the volatile components produced by weed seeds. Inhibition of seed germination was accompanied by decreased O2 levels and production of volatile metabolites identified as acetaldehyde, ethanol, and acetone. The effectiveness of these compounds in reducing germination was dependent on O2 levels.

Biological Control of Crown Gall: Seed Inoculation

Abstract: Summary: Peach seeds were inoculated with the nonpathogenic isolate 84 of Agrobacterium radiobacter var. radiobacter biotype 2 before sowing in natural soil heavily inoculated with the tumour inducing biotype 2 isolate 27 (A. radiobacter var. tumefaciens). Nonpathogens (presumably isolate 84) became predominant in the biotype 2 population on roots, on underground stems and in the soil round plant crowns. Significant (P < 0·001) biological control of crown gall was achieved. Total gall incidence on plants grown from inoculated seed was 31% and from uninoculated seed 79%; the corresponding gall incidence on plant crowns was 12% and 76%. Dusting seed with Thiram (3·1 g/kg seed) did not significantly reduce disease incidence. Infection appeared to occur through undamaged lenticels indicating that wounding is not a necessary prerequisite for crown gall induction in peach.

Influence of birds, stones and soil on the establishment of pasture juniper, juniperus communis, and red cedar, j. virginiana in new england pastures'

Abstract: In New England the pasture juniper, Juniperus communis var. depressa Pursh, usually occurs in pastures adjacent to stones, whereas the red cedar, J. virginiana var. crebra Fern. & Grisc., occurs either at stoneside or in interstonal areas. In non-stony pastures red cedar is often dominant and pasture juniper absent. Accordingly, attempts were made to determine the effects of the stoneside position. During their fall migrational flights, robins, Turdus migratorius Linnaeus, feed heavily on the berries of both pasture juniper and red cedar, and are effective disseminators of the seed. During feeding periods the robins come to rest on exposed field stones and the seed in their droppings becomes concentrated on the stones. The seeds are subsequently washed and planted into frost-heave cracks adjacent to the stones. The burial of pasture juniper seed assures their retention in a moist condition during the long, double stratification period required for their germination. Red cedar seed requires only a single cold stratification period, however, and this may be encountered even when seeds are planted on soil surfaces. Seedlings developing in the stoneside frost-heave crack are protected from trampling or grazing, and they receive extra moisture from their stone micro-watershed. Yet, all items in the system are not favorable. Seedling junipers make their best growth in compacted soils, like those away from stoneside, and although birds are effec- tive disseminators of their seed, the passage of seed through the birds gut inhibits germination.. Nevertheless the fortuitous planting of seed on exposed stones introduces pasture juniper and red cedar to a micro-habitat that more than compensates for reduced germination and slower growth.

Effects of Environment Before Harvesting on Viability

Abstract: It is well known that the germination and viability of seeds of cultivated plants can vary greatly from year to year, dramatically affecting the value of the seed for sowing. To reduce the risks of crop failure that can result from sowing poor seed, most countries now have laws prohibiting the sale of seed lots unless they have a germination greater than a statutory minimum percentage, which varies according to the species. Germination tests, carried out according to the widely used International Rules (Anon., 1959) reveal only the percentage of the seeds that are viable under near-ideal conditions and there is usually a considerable discrepancy between the results of germination tests in the laboratory and the emergence of the seeds in the field, the discrepancy usually being greater the lower the per cent germination (for examples see Perry, 1967 and Austin, 1963).

Early Development of Johnsongrass

Abstract: Tillering, flowering, and rhizome formation of johnsongrass (Sorghum halepense (L.) Pers.) started approximately 2 months after planting seeds or single-node rhizome fragments in the warm season. The minimum temperature for rhizome formation was between 15 and 20 C. Inflorescences were produced only from May to November. No causal relationship was found between flowering and rhizome formation. The bud activity of new rhizomes, as assessed by sprouting of single-node fragments, ranged between 48 and 100%. Sprouting was nil at 10 C, slow below 20 C, and maximum at 28 C. Seed germination required a temperature about 10 C higher than rhizome sprouting. While the initial leaf production of seedlings was more rapid than on plants produced from rhizomes, other differences in growth and development between seedlings and rhizome plants were of only limited practical significance.

Effects of environment on the relation between seed protein and seedling vigor in wheat

Abstract: Wheat seedlings grown from seeds of different protein levels, obtained from an N fertilizer field trial, showed significant differences in dry matter and a high positive correlation (r = 0.920**) between seed protein content and dry matter after 3 weeks’ growth. In further studies using low and high protein seeds (99 and 142 mg/g), dry matter differences were obtained at up to 40 days from sowing and in different temperature and light intensity environments with nutrient concentrations containing up to 24 mM nitrate. Maximum dry matter accumulation occurred at approximately 5 mM nitrate but no limit was reached in protein accumulation with up to 24 mM nitrate. Seedlings grown from high protein seeds were shown to be more advanced in morphological development than those seedlings grown from low protein seeds.

Emergence of honey mesquite seedlings relative to planting depth and soil temperature.

Abstract: Maximum emergence occurred when honey mesquite (Prosopis glandulosa Torr, var. glandulosa) seeds were planted 0.5 cm deep at a soil temperature of 27 C. Percent emergence was severely reduced at a soil temperature of 18 C, regardless of planting depth. Seeds placed on the soil surface germinated, but seedlings did not survive. Seeds planted 5 to 6 cm deep germinated, but no seedlings emerged. Rate and extent of emergence in a nursery were evidently dependent on the temperature reaching 24 C in the surface 2.5 cm of soil.

The growth and performance of rain-grown cotton in a tropical upland environment: II. The relationship between yield and growth

Abstract: SUMMARY An hypothesis, based on Mason's nutritional theory of boll shedding, was set up to relate the yield of cotton to crop growth in three agronomic experiments. It was postulated that bolls were set only if the demand for carbohydrates of the metabolic sink which they formed did not exceed the supply, both of which were estimated. Two components of the sink were recognized — the daily growth rate of a single boll, DGRB, and the number of bolls on the crop plants. The effects of genotype and environment on these components were analysed. Their product gave the size of the boll sink, CB, which was compared with the crop growth rate, C, to indicate respectively carbohydrate demand and supply. Three sets of evidence to support the hypothesis were considered: (i) when C B > C, the number of bolls, and hence the size of the sink, ceased to increase, and bolls started to shed heavily; (ii) a model to predict yield, based on the hypothesis, accounted for all non-random variation in yield between sowing dates and varieties; (iii) the correlation between yield and various crop attributes, recorded before picking, became strikingly closer between 110 and 130 days from sowing when C B > C, suggesting that yield was determined during that period of time. The network of relationships, studied in these papers in order to relate the yield of a cotton crop to its environment and genotype through their effect on its growth, indicates the form of a dynamic model to simulate growth and predict yields.

The effect of surface treatments on soil water storage and yield of wheat

Abstract: Soil water changes under six pre-seeding surface treatments and the following wheat crop were recorded at three- to four-weekly intervals in two consecutive seasons (1966-67 and 1967-68) on a hard setting red-brown earth in South Australia. The treatments were 'fallow' (initial cultivation in spring, nine months before sowing), 'grassland' (initial cultivation in autumn, two months before sowing), 'chemical fallow' (sprayed with herbicides in spring), and three fallows separately modified with gypsum, straw and hexadecanol. In both experiments grassland lost water rapidly in spring and this lower water content was never completely restored. The fallow + straw gave the biggest recharge of soil water following rain and the highest water storage efficiency during the fallow period. In 1966-67, recharge of soil water followed rain in summer at a time of high evaporation rates. The effectiveness of the treatments in increasing soil water storage was related to their ability to reduce evaporation. In 1967-68, soil water recharge occurred in autumn when evaporation rates were low. The effectiveness of the treatments was then related to their ability to curb surface sealing by raindrop impact. Nitrate-N contents in the top 60 cm of soil at seeding were higher in 1967 than 1968, probably due to efficient mineralization in 1967 after summer rain, and leaching by heavy rain and denitrification before seeding in 1968. Crops on the fallow + straw treatment used most water and produced the highest wheat yields with the highest water-use efficiency in both years.

Effect of Planting Date on Water-Use and Its Efficiency in Dryland Grain Sorghum1

Abstract: It has been postulated that water regime was the major operative factor responsible for different yield response of dryland grain sorghum [Sorghum bicolor (L.) Moench] to different planting dates. Our research was done in order to appraise this postulation. For four consecutive years, four grain sorghum hybrids were planted on two planting dates (March 20–24 and April 12–16) in Israel under conditions of limited water supply as determined by the amount of stored soil moisture prior to planting. Vegetative development, grain yield, and soil water extraction profiles were determined. Early planting, as compared with late planting, increased grain yield through increased tillering and greater weight per grain. During the period from emergence to 51 days, early planted sorghum used about halt as much water as late-planted sorghum. Early planted sorghum was less water stressed, as evidenced by lower leaf diffusive resistance prior to heading and smaller reduction in LAI (leaf desiccation) after heading, as compared with late-planted sorghum. Lower water use in early planted sorghum, during the period prior to heading, was ascribed to lower potential evapotranspiration, smaller LAI, and possibly slower root development, as compared with the respective period in late-planted sorghum. Total amount of water used at maturity did not differ between planting dates, apparently due to the longer period of growth and the larger amount of stover dry matter per plant in early planted sorghum, which served to offset the decreased water use during the earlier phase of growth. No appreciable differences were found between hybrids tested in terms of adaption to early planting or water use.

Systemic action of benomyl against late-wilt disease of maize.

Abstract: SUMMARY Benomyl (methyl-I-(butyl carbamoyl)-2-benzimidazole carbamate) at 2.5 to 100 ppm completely inhibited the growth in vitro of Cephalosporium maydis Samra, Sabet & Hingorani, the causal fungus of late-wilt of maize. In pot experiments, late-wilt was controlled by applications equivalent to 10 ppm benomyl/unit wt dry soil at sowing but not by applications 30 days after sowing or by seed treatments (dusts and dips). A fungitoxic substance was detected in benomyl-treated soil, planted with maize, 120–150 days after treatment and for 150–180 days in unplanted soil. Sap expressed from maize grown in benomyl-treated soil was also fungitoxic, especially that from the roots and distal parts of the leaf blades. In the field, soil applications of benomyl to 10 kg/feddan (4200 m2) failed to control late-wilt. Tests indicated little fungitoxicity in the sap of maize plants 25 days after sowing.

Strip-Cropping Effects on Abundance of Heliothis -Damaged Cotton Squares, Boll Placement, Total Bolls, and Yields in Oklahoma

Abstract: Damaged squares, boll placement, total bolls, and yields from cotton given within plantings of corn, soybeans, alfalfa, peanuts, sorghum, and a check (no crop planted on either side of the cotton) were determined during 2 fruiting seasons. Two generations of Heliothis each year caused the greatest damage to squares in the corn treatment and the least damage in the sorghum treatment. Planting corn, alfalfa, sorghum, and peanuts adjacent to cotton increased the percent damaged squares over the check when both years were averaged. No treatment differences were observed between the number of bolls on the plants. In 1970, fewer plants per foot of cotton row produced significantly more bolls on the bottom half of the plants than did plants spaced closer together, but no differences were noted among treatments. Averaged over both years, the sorghum-treated plots produced the most seed cotton and the corn-treated plots the least. It appears that planting sorghum in a stripcropping system with cotton could be advantageous not only by encouraging and protecting beneficial insects but also by offering other desirable treatment effects.

Germination response of dormoat seeds to low temperature and gibberellin

Abstract: Dormoats are derivatives of crosses between Avena sativa L. and A. fatua L., designed to be sown in the fall to germinate the following spring. Strains vary in levels of seed dormancy at harvest and in their rates of after-ripening in dry storage. Germination of the seeds is stimulated by gibberellic acid. Embryos isolated from dormant seeds exhibit no dormancy but their germination is prevented by abscisic acid. Low temperatures (ca. 7 C) stimulate germination to different levels in various strains. Seeds enter a secondary dormancy when they fail to germinate in the imbibed state due to primary domancy. Seeds with secondary dormancy are not stimulated to germinate by low temperatures until partial after-ripening of the seeds in the dry state has occurred, but germination is stimulated by gibberellic acid without after-ripening. Secondary dormancy is proposed as a factor in the maintenance of undergerminated seed in the soil from fall planting into winter.

Correlation studies between yield and some agronomic characters in bambara groundnut (Voandzeia subterranea Thouars)

Abstract: SUMMARY In 27 local varieties of bambara groundnut, there was some association between the number of days from sowing to germination, earliness, internode length, petiole length, number of stems per plant, terminal leaf area, shell thickness, number of pods per plant, number of seeds per pod, seed size, and yield of seeds per plant. Fifty-five coefficients show the degree of correlation between 11 agronomic characters. Yield was highly significantly and positively correlated with days to first germination and maturity, number of pods per plant, number of seeds per pod and 100 seeds weight, and negatively correlated with the other characters. Although yield is highly correlated with all 10 characters, earliness in germination and maturity, number of pods per plant, number of seeds per pod, number of stems per plant and seed size appear to be the best criteria for selection.

Studies on the Seed Germination of Palms

Abstract: The purpose of this study is to know the mechanism and optimum condition of seed germination for three palms, Chrysalidocarpus lutescens, Mascarena verschaffeltii and Phoenix dactylifera. The seed of Chrysalidocarpus lutescens is global with a slightly pointed edge in the top, while that of Mascarena verschaffeltii is slightly slender oval. These two kinds of seeds are uniform in their tissue of endosperm and they have a tongue-like cotyledon which elongates at a position close to the seed when the germination takes place. The seed form and germination pattern of Phoenix dactylifera are similar to those of Phoenix canariensis, but the seed size of P. daclylifera is a little larger than that of the latter.The percentage of seed germination in Chrysalidocarpus lutescens was only 30, while those in Mascarna and Phoenix were over 90 at the optimum temperature. The optimum temperature of seed germination seems about 25°C for Chrysalidocarpus. For Mascarena, optimum was 25°C to 35°C, the highest percentage being obtained especially at 35°C. For Phoenix, the optimum range of temperature was similar.The least number of days from planting to germination was 25, 17 and 15 in Chrysalidocarpus, Mascarena and Phoenix, respectively. The favorable seed bed was vermiculite and sand, sand and clay loam for Chrysalidocarpus and Mascarena, respectively. However, there was no difference among beds examined in Phoenix. The seed of Chrysalidocarpus was so easy to dry that it had lost the germination power two months after harvest. Although the fresh weight of seed of Phoenix reduced about 76% after the storage in room for one year, the seed maintained the germination power at 70%.

Subsoil amendment material incorporating method and apparatus

Abstract: Method and apparatus for preparing the soil prior to seed planting. The apparatus is preferably drawn by a tractor and includes a plow which turns the topsoil to expose the subsoil as the apparatus advances. Dispensing apparatus conducts soil amendment material from a hopper through a plurality of tubes to a box behind the plow. The box has discharge outlets which are arranged across a substantial width of the furrow formed by the plow. A rotary tiller is positioned behind the box and mixes the amendment material into the subsoil to a depth greater than the plow.

Monogerm sugar-beet seed production experiments

Abstract: Eight experiments investigated how different sowing and harvest dates, plant populations and fertilizers affect yield, germination and size of seed from hybrid monogerm sugar-beet seed crops, grown in situ when raised under barley cover in Lincolnshire, or open sown in Oxfordshire. Weather at seed harvest was wetter than average in 1968, average in 1969, and drier in 1970. Most seed of good quality came from plant populations of 300000 plants/ha sown in early July, given ample P and K fertilizer in the seed bed and 150–200 kg/ha of N in the spring of the second year in Oxfordshire or 200–250 kg/ha N in Lincolnshire. Harvesting in early September on average yielded most seed. Methods used to grow multigerm seed proved suitable also for monogerm seed but the percentage germination was lower for monogerm than multigerm seed.

Carry-over effects of sprouting and haulm destruction in the potato seed crop

Abstract: Seed of differing maturity dates of cv.Arran Pilot andMajestic were produced by planting sprouted and unsprouted mother tubers and by either destroying the foliage 2–3 weeks before senescence or allowing natural maturity to take place. Seed from crops of earlier natural maturity sprouted earlier and inArran Pilot grew faster if sprouting was encouraged soon after harvest. Other small differences in sprout growth were recorded, but none of the treatments applied to the first generation crop affected the time of emergence, stem number, growth of foliage or tubers in the second generation crop.

The selective chemical control of Wimmera ryegrass in wheat with di-allate and tri-allate

Abstract: Two herbicides, di-allate and tri-allate, were compared for the pre-emergence control of Wimmera ryegrass (Lolium rigidum) in wheat at three different locations in the Victorian wheatgrowing areas. Both herbicides significantly reduced ryegrass populations in the crop, but di-allate was consistently more effective than tri-allate. Grain yields were generally enhanced by spraying, but 1.12 kg a.i. per hectare of either material sometimes caused crop damage when applied before sowing. On an economic basis, di-allate at 0.56 kg a.i. per hectare was superior to all other treatments whether applied just before or just after sowing.

Phytochrome and seed germination

Abstract: Summary Both tobacco ‘Virginia Gold’ and Plantago hirtella seed germinate on exposure to red light. During the first day or so after sowing, the response can be stopped by a following exposure to deep-red, indicating phytochrome action. However, the effects of successive exposures to red are additive through intervening exposures to deep-red. Moreover, after several days in the dark, both red and deep-red induce germination.

Weather factors affecting the development of maize from sowing to flowering

Abstract: SUMMARY The phenological development from sowing to flowering of the eaxly maize hybrid INRA 200 is related to the weather conditions. Plot trial data from Wytham, near Oxford, England, and weather information from that and nearby sites formed the basic data. The mean rate of development per day from sowing to emergence is related by linear correlation analysis to the mean values of soil temperature at 5 cm depth and soil moisture deficit. A range of temperature thresholds for emergence development exist, which depend upon the soil moisture, and which differ from the true physiological threshold. Between omergence and flowering the mean rate of development per day is related by linear correlation analysis to mean air temperature, solar radiation and potential transpiration estimated from weather data. All correlations are significant, but the parameters which combine radiation and temperature are statistically better.

Weed control for close-drilled soybeans.

Abstract: Delayed planting or "stale seedbed" for weed control in close-drilled (20-cm rows) soybeans [Glycine max (L.) Merr. 'Amsoy'] was evaluated for 3 years. The system combined final seedbed preparation 3 to 6 weeks before planting with herbicide application at planting time. The best control of six weed species and highest soybean yields were obtained by a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) application at the time of seedbed preparation followed by 3(3,4-dichlorophenyl)-l-methylurea (linuron) application at planting and by linuron application at planting without the early trifluralin application. Applications of 1,1'-dimethyl-4,4'bipyridinium ion (paraquat) at planting, either with or without trifluralin treatments, resulted in less weed control and lower soybean yields than comparable treatments with linuron. However, even the best treatments failed to provide the weed control necessary to prevent substantial soybean yield reduction in heavy infestations of weeds that emerge in large numbers after planting, and that resist the phytotoxic action of the herbicides.

Studies on the Emergence of Rice Seedlings in the Direct-Sowing Culture : V. Effect of high temperature treatment of seeds before sowing on the emergence in paddy rice seedlings

Abstract: In this study, effect of high temperature treatment of seeds before sowing on the emergence in paddy rice seedlings were examined. Materials were two paddy rice varieties "Koshijiwase" and "Hoyoku" in japonica type, and cultural temperature was about 20°C. Seeding-depth were 5 and 7cm, and soil moisture content was about 19 per cent (pF value was about 3). The following results were obtained. 1. High temperature treatment of seeds before sowing promoted the emergence in rice seedlings. The promotion was more obvious under the conditions of 5 cm or more depth of seeding and compacted covering soil. 2. The most effective high temperature treatment of seeds before sowing was as follows. (i) Moisture content in seeds before the high temperature treatment; 24-27 per cent. (ii) Volume of vessel in which contains seeds during the high temperature treaument; 4-40 times larger than the volume of seeds. (iii) High temperature treatment; 4-8 days at 40-44°C.