Planting densities

Every continent, except Antarctica, grows com 40% of the present world crop is produced in the United States. In the 1987—1988 crop year, 12 states (Iowa, HI., Nebr., Minn., Ind., Ohio, Wis., Mo., S. Dak., Mich., Kans., and Tex. in order of production) produced 157.5 million metric tons (6.2 biUion bushels) that was 88% of the United States and 36% of the world s crop (66). Yield is influenced by many factors, including climate, pest control, planting density, and fertilization. Yield in the United States has increased from about 1.5 metric tons /hectare in the 1930s to about 7.5 metric tons /hectare. In 1985, a test plot produced 23.2 metric tons /hectare and yields approaching 40 metric tons /hectare are considered possible com is the most productive of the principal food crops. 

Artificial Controlled-environment laboratory Elevated CO, plant density Perennial ryegrass (Lolium perenne),v/hite do- 84... 

Natarajan, S., Stamps, R.H., Saha, U.K., and Ma, L.Q., Phytofiltration of arsenic-contaminated ground-water using Pteris Vittata L. Effect of plant density and nitrogen and phosphorus levels, International Journal of Phytoremediation, 10 (3), 222-235, 2008. 

Conservative is used to define orchard and management factors that once introduced cannot, or are extremely difficult to, change or require substantial additional investment to do so. Among these are soil and other site-specific conditions, choice of variety/cultivar and rootstock, planting density and tree canopy formation, system stabilisation measures at orchard set-up and installations to buffer extreme events. 

As a result, organic fruit growers have to make maximum use of preventative or indirect plant protection measures, some of which were already described in terms of their effect on fruit quality (e.g. lower planting densities, see sections above). However, there remains an increased risk for pests and diseases causing stress, decreased photosynthetic activity and capacity. Also in certain sensitive cultivars, the application of permitted plant protection products (such as lime sulphur) can result in phytotoxic effects or latent stress in trees (Palmer et al, 2002). The decrease in photosynthetic activity by both pest/disease attack and pesticides may, in turn, result in reduced fruit quality. Both long-term latent and short-term acute side effects of organic plant protection products have not yet been sufficiently investigated. 

Although the residual effects of repeated applications of solid manure are known to persist for many years, the residual effects of slurry application are generally low [7, 8]. Changes in plant species composition and plant density,... 

Suzuki Y, Takabayashi T, Kawaguchi T, Matsunaga K (1998) Isolation of an allelopathic substance from the crustose coralline algae, Lithophyllum spp., and its effect on the brown alga, Laminaria religiosa Miyabe (Phaeophyta). J Exp Mar Biol Ecol 225 69-77 Svensson CJ, Pavia H, Toth G (2007) Do plant density, nutrient availability, and herbivore grazing interact to affect phlorotannin plasticity in the brown seaweed Ascophyllwn nodosum. Mar Biol (in press), doi 10.1007/s00227-007-0649-5 Swanson AK, Druehl LD (2002) Induction, exudation and the UV protective role of kelp phloro-tannins. Aquat Bot 73 241-253... 

Svensson CJ, Pavia H, Toth GB (2007) Do plant density, nutrient availability, and herbivore grazing interact to affect phlorotannin plasticity in the brown seaweed Ascophyllum nodosum Mar Biol 151 2177-2181... 

The resnlts broadly tally with experimental findings for rice. The maximum length of primary root required to sustain a plant depends on soil conditions and planting density. Typically the depth to the plongh pan in a puddled ricefield is less than 2 dm, and a typical spacing between plant hills is 25 cm x 25 cm... 

Non-crop plants associated with the crop species offer possibilities for allelopathic weed control. In this study Brassica campestris (wild mustard), which is an important weed in Santa Cruz County, and broccoli, a common crop, were intercropped, The allelopathic potential of both species and the changes in this potential throughout their life cycle were demonstrated with experiments in the laboratory. Effects of different planting densities and sowing time of canpestris on the crop yield are analyzed. Preliminary steps to separate the physiologically active compound(s) are described. The possibilities for the use of Brassica campestris in agroecosystem design as a non-crop plant that promotes pest control are described. 

Plant response in the ASTROCULTURE flight experiment. Soc. Automotive Eng. Tech. Paper 951624. Muro, J., Diaz, V., Goni, J. L., Lamsfus, C. (1997). Comparison of hydroponic culture and culture in a peat/sand mixture and the influence of nutrient solution and plant density on seed potato yields. Potato Res., 40,431 38. Musgrave, M. E. (2002). Seeds in space. SeedSci. Res., 12, 1-16. 

Bulson, H.A.J., Snaydon, R.W. and Slopes, G.E. 1997. Effects of plant density on intercropped wheat and field beans in an organic system. Journal of Agricultural Science 128(1) 59-71. 

Tree Density Planting density of an orchard can be used to manage weeds. As the density increases, particularly in the row, the orchard floor surface becomes shaded more rapidly by tree canopies, suppressing weed growth (Tucker and Singh, 1983). 

Adjustments of row spacing, plant density, or row direction to control pests. 

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