Seed rates

Nonchemical or traditional practices, such as weed seed removal, optimal crop seeding rates, crop selection, enhanced crop competitiveness, crop rotation, and mechanical weed control are all important components of an effective weed management program (458,459). In the context of modern intensive chemical herbicide appHcation, nonchemical practices may even represent an innovative approach to weed management and should receive careful consideration. 

Malhotra, S.K. and Vashishtha, B.B. (2005) Effect of seed rate and row spacing on growth, yield and essential oil of ajowan (Trachyspermum ammi L.) genotypes. Indian journal of Arecanut, Spices and Medicinal... 

If the two types of operation are compared on the basis of equal growth rate, production rate, and suspension weight, then residence time (0B) and reference size (L) will also be equal. The two cases can be equated only by an adjustment in seed rate to satisfy the relation... 

Thus, the required seed rate for mixed product is about eleven times the number required for classified product. On a weight basis, however, this is not very significant, since Saeman s equations show that 77% of the mixed product will contain the same number of crystals that is found in 100% of the classified product. Seed-rate control is achieved in practice by segregation and removal of excess nuclei (fines) as quickly as possible. Several examples of actual operation are described by Saeman (SI). 

Optimum seed control size in relation to product size and inherent nu-cleation rate of the system (c) Fines trap capacity to assure effective control of seed size chosen (d) Phasing of seed rate adjustments in relation to corrections or changes in product size and (e) Sensitivity of measurement and control procedures to assure effective and steady size control of product. 

A transplantation technique should be developed to enable proper alignment of the graft tissue, high seeding rate of the transplanted cells, and minimal damage to the host tissue. 

Harvest losses of safflower can be one to live times the recommended seeding rate. Safflower seeds have some short-term sprouting resistance but no seed dormancy, which limits persistence in the soil seed bank. This oilseed is attractive to seed predators, including small mammals and birds (personal observation), which may reduce seed density but may facilitate transport of seed from the field. The distance and amount of seed transported by animals have not been quantified, and the fate of transported seed is unknown. Volunteer populations are restricted to the first follow year in conventional fields. Although they can be controlled by conventional herbicides in subsequent crops, there is the potential for survivors to flower, set viable seed, and contribute to both PMGF and SMGF. 

These theoretical considerations, applied to a short treatment involving seeding with tartrate crystals, show that great care and strict snpervision is required to ensure the effectiveness of artificial cold stabilization. The following factors need to be closely monitored the wine s initial state of snpersaturation, the particle size of the added tartrates, the seeding rate, the effectiveness of agitation at maintaining the crystals in snspension, treatment temperature and, finally, contact time. 

Calculating the saturation temperature of a wine prior to cold stabilization provides information on the optimum seeding rate for that wine. Indeed, it is not necessary to seed at 400 g/hl, as often recommended, if 40 g/hl are sufficient. 

Among the important points that determine the suitability for use as a green manure, aside from climate, season, and soil, are availability and cost of seed, rate and amount of growth, how well it fits into the cropping system, primary purpose for which it is grown, type of root system, ability to compete with weeds, ease of incorporation of the crop into the soil, probable effect on the subsequent crop, and many others. 

Huan NH, Thiet LV, Chien HV, Heong KL. Farmers participatory evaluation of reducing pesticides, fertilizers and seed rates in rice farming in the Mekong Delta, Vietnam. Crop Prot 2005 24(5) 457-64. 

Seed rate may vary according to the rye cultivar and vegetation year (germination capacity, thousand seed mass), however, assuring 4.5 to 5 millions germs per hectare (10000 m ) is essential. 

Pageau, D. and Wauthy, J.M. (1995) Seeding date and seeding rate effects on ergot development on barley. Can. J. Plant Sci., 75, 511-513. 

Crop seed rates. High seed rates and good crop establishment all help to reduce the impact of weeds. 

Farming activities. Rotatiorr, variety choice, time of sowing, seed rate, fertiliser itse, irrigation and cultivations can all affect the amount of disease that is present. 

Late sown wheat after vegetables, potatoes, sugar beet or peas are most at risk. Increase seed rates in susceptible fields. Use insecticide treatments if thresholds reached. 

Root crops, e.g. sugar beet, swedes and carrots also kale. These crops have small seeds and so the seedbed must be as fine as possible, level, moist and firm. This is very important when precision drills and very low seed rates are used. Good, early, ploughing with uniform, well-packed and broken furrow shces will considerably reduce the amount of work required in the spring when, if possible, deep cultivations should be avoided to keep frost tilth on top, leaving unweathered soil well below the surface. 

As well as the physieal distribntion of the seed, the technology can also allow differential seed rates to be ehanged on the move to allow for the differences across a field in soil type, eondition and nutrition status. This allows optimisation of seed rates to allow, we hope, higher yields and less seed wastage. 

High seed rates can help reduce weed competition. In winter cereals drilling 500seeds/m compared with 200seeds/m can halve the weed biomass. In horticultural crops it is not always possible to plant high populations as this technique can affect crop quality and lead to poor marketable yields. 

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