Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

Seed Coating Technologies and Treatments for Onion: Challenges and Progress

Abstract: Conventional methods to control the onion maggot or onion fly, Delia antiqua (Meigen), have relied on in-furrow applications of the toxicant pesticide, chlorpyrifos. The objective of this research was to develop an onion (Allium cepa L.) seed treatment that utilizes a new chemistry compound that is environmentally safe. Cyromazine is an insect growth regulator with a mode of action different from traditional pesticides used to control onion maggot. Cyromazine has low mammalian toxicity and is relatively nontoxic to other insects, including beneficials. High seed loading rates (50 g.kg -1 active ingredient) are required for optimal efficacy, and conventional slurry methods are inadequate to apply these high loading rates. Film coating and pelleting were performed at Cornell Univ. to apply cyromazine and a registered fungicide (a formulation of thiram and carboxin) to onion seeds. Results of field studies performed over several years revealed that stand losses due to the onion maggot ranged from 20% to 60%. Cyromazine applied by either film coating or pelleting decreased the loss by onion maggot from 1% to 8%, and efficacy was comparable to an in-furrow application ofchlorpyrifos. Cyromazine was registered as a seed treatment and is commercially used in the northeastern and midwestern United States, where onion maggot is a serious pest. Field emergence was not negatively affected by cyromazine coated onto the seeds when onion seeds are sown in organic (muck) soils. There is other evidence, however, that cyromazine seed treatments may cause phytotoxicity to germination and seedling growth. Testing seed quality in sand or on roll towels revealed a high percentage of abnormal seedlings. Retarded root growth was observed in seeds treated with cyromazine, resulting in an increase in abnormal seedling classifications. A finely ground sphagnum peatmoss applied over the seeds in a roll towel test ameliorated the abnormal root growth symptoms, and seedlings had robust growth. Collectively, film coating and pelleting were effective delivery systems for the application of plant protectants required at time of sowing. Modification of the standard germination test was needed to accurately assess onion seed quality. Moreover, this project was successful due to a team effort of a university seed scientist and entomologists working with onion growers and industry. Future registrations on small acreage, high-value horticultural crops are envisioned to require similar multi-partner approaches.

Seed production and germination in two rare and three common co-occurring Acacia species from south-east Australia

Abstract: Seed set, size, viability and germination requirements were investigated for two rare (Acacia ausfeldii and A. williamsonii) and three common (A. pycnantha, A. genistifolia and A. paradoxa) co-occurring congeners in box-ironbark eucalypt forests near Bendigo, south-east Australia to investigate correlates of rarity. Seed size was significantly smaller for the two rare species and germinants were less able to emerge from deeper sowing depths than were the larger seeded common congeners. All species had a strong heat-stimulated germination response. While the rare A. ausfeldii showed strong germination only at the highest temperature treatment (100°C), the common and widespread A. pycnantha showed strong germination across a broad range of temperatures (60-100°C), likely to be experienced by soil-stored seeds during a fire. Seed viability, number of seeds per plant, and number of firm, aborted and eaten seeds per pod varied between species, but the pattern of variation was not related to rarity. Small seed size and a very specific temperature requirement for germination may help to explain rarity in A. ausfeldii, and to a lesser extent in A. williamsonii. Fires are often patchy and heating of the soil is likely to be highly spatially variable, so species with germination responses to a broad range of temperatures have an advantage over those that respond only to a narrow range. A narrower range of soil depths from which seeds can emerge will further reduce the proportion of the seed bank that might recruit following fire. Human impacts on species habitats, such as fragmentation, loss of topsoil through mining, timber harvesting, grazing and urbanization, and consequent reduction in fire intensity, are likely to have further contributed to rarity in these species. The role of pollination and other factors in relation to population size is the subject of further investigation.

Effects of Straw Mulch on Pest Insects, Predators, and Weeds in Watermelons and Potatoes

Abstract: Physical and biotic effects of straw mulch applied at two different times to potatoes and watermelons were assessed in field trials over 2 yr. Plots with straw mulch generally had lower soil temperatures and higher soil moisture than control (weedy, no straw) plots. When straw was applied at planting weeds were suppressed, whereas straw applied after cultivation 4 wk after planting had less effect on weeds. In 2000, potatoes with straw at planting had fewer potato leafhoppers, Empoasca fabae (Harris) (and less associated plant damage) and more colonizing Colorado potato beetle, Leptinotarsa decemlineata (Say), adults than the other treatments. Subsequent Colorado potato beetle egg mass and larval numbers, however, were not higher in this treatment, possibly because of the higher numbers of predators in these plots as assessed by pitfall trapping. In 2001, there were no differences in numbers of colonizing potato leafhopper or Colorado potato beetle adults, but by midsummer there were more Colorado potato beetle larvae in the control plots than in the straw plots, again possibly due to differential predation. The few pests observed in the watermelon plots were not affected by the straw treatments. Potato yields were similar in all treatments, but melon yields were higher in plots with straw at planting (in which weeds were suppressed) in 2000. In 2001, when melons were planted earlier in the spring, melon plant biomass at 4 wk was lower in plots with straw at planting than in the other treatments, probably due to reduced soil temperatures. Thus, for potatoes, straw may be useful to control weeds and enhance predator numbers, but insect pests may still require control. In melons, straw should be used only if the crop is planted after the soil is sufficiently warm.

Weed productivity and composition in sole crops and intercrops of barley and field pea

Abstract: (1) The hypothesis that intercrops have fewer, smaller weeds than their component sole crops was tested by sowing pure and mixed crops of barley and field pea at commercial densities and at double these densities in two fields near Ithaca, New York, U.S.A. The effect of these cropping systems on the species composition of associated weeds was also investigated. (2) For both sole crops and intercrops weed productivity decreased and crop productivity increased with higher crop density. (3) Crop treatments had no effect on weed numbers relative to unplanted control treatments. (4) For both highand low-density treatment series, weed productivity decreased in the order unplanted controls > pea sole crops > intercrops > barley sole crops. Weed productivity in the high-density intercrop, formed by sowing together the two low-density sole crops, was not significantly different from weed productivity in the low-density barley sole crop. (The estimated difference+S.E. was 0 77+21 8 g m-2.) (5) Weed suppression by barley may have resulted from competition for soil moisture since weeds which grew in barley sole crops or barley/pea intercrops had lower predawn water potentials than weeds in unplanted controls or in pea sole crops. (6) Within both density series, above-ground crop productivity decreased in the order barley > intercrop > pea. Yield of the high-density intercrop was nearly equal to the sum of yields of the two low-density sole crops. (7) Relative abundance of the major weed species differed among crop treatments. In general, the most dominant weed species was more suppressed than other species as crop productivity increased. This response is explained in terms of a dominance hierarchy.