Annual crops

Lettuce has been studied in detail and will be used here to demonstrate the capabilities of calorimetry in helping to guide production of annual crops. To maintain a steady supply of commercial lettuce, plants are grown throughout the year at locations with different climates. For maximum yield, it is important to plant varieties with growth properties matched to the climates. This has been largely an empirical procedure. Fontana et al. [106] describe rapid metabolic rate measurements to identify suitable growth climates. Commercial lettuce 

Measurement of plant metabolic properties has the potential to contribute strongly to ecological studies in the future. It is hypothesized that inferences about species distributions and changes in species distributions can be drawn from knowledge of the effects of temperature on respiratory parameters. The hypothesis suggests calorespirometry can be used to study plant distribution and temperature linked responses of plants in the wild. 

Little information is currently available on the physiological parameters that control plant distribution changes in response to temperature changes. Mo.st studies of the effects of temperature on species distribution have focu.sed on plant survival and reproductive ability when confronted with climatic temperature extremes and on the biochemistry of responses to extreme temperature events [109]. However, temperature affects plants in two ways. Extremes of temperature, either high or low, can kill or prevent reproduction. 

This is well known and the process is well characterized, i.e. the effects of an extreme temperature event are reasonably predictable. What is much less appreciated and poorly characterized in ecology is the effect of small changes in temperature regimen on growth (competitive success) and reproduction (reproductive success) of plants even when extreme limits are not exceeded [110, 111], 

Calorimetry of higher organisms. In H.D. Brown (Ed.) Biochemical Calorimetry, Academic Press, New York, 1969. p. 181. 

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Annual cropping by traditional methods requires more labor, and yields are generally lower. Although animal power can help reduce human labor and provide manure for fertilizer, draught animals must be either fed by some of the crop or pastured, thereby increasing the land area required per person unless yields per unit of land increase accordingly. Average livestock ate one-fourth of the yield in the early nineteenth centuiy. 

About 1.5 billion hectares of crop land are planted for annual crops and permanent crops. About one third of the arable and permenant crop-land is located in the United States, India, and China. Out of 1.5 billion hectares, 263 million hectares arc irrigated. Irrigated lands in China and India account for the largest share—about 110 million hectares. 

Potential resources of xylans are by-products produced in forestry and the pulp and paper industries (forest chips, wood meal and shavings), where GX and AGX comprise 25-35% of the biomass as well as annual crops (straw, stalks, husk, hulls, bran, etc.), which consist of 25-50% AX, AGX, GAX, and CHX [4]. New results were reported for xylans isolated from flax fiber [16,68], abaca fiber [69], wheat straw [70,71], sugar beet pulp [21,72], sugarcane bagasse [73], rice straw [74], wheat bran [35,75], and jute bast fiber [18]. Recently, about 39% hemicelluloses were extracted from vetiver grasses [76]. 

Cooper, P.J.M., Gregory, P.J., Tully, D. Harris, H.C. (1987). Improving water use efficiency of annual crops in the rainfed farming systems of West Asia and North Africa. Experimental Agriculture, 23,113-58. 

Pesticides used on crops grown on the test site in previous seasons may also have an impact on the outcome of a field residue trial. Carryover of prior pesticide applications could contaminate samples in a new trial, complicate the growth of the crop in a trial, or cause interference with procedures in the analytical laboratory. For this reason, an accurate history of what has transpired at the potential test site must be obtained before the trial is actually installed. The protocol should identify any chemicals of concern. If questions arise when the history is obtained, they should be reviewed with the Study Director prior to proceeding with the test site. In most annual crop trials, this will not be a significant issue owing to crop rotations in the normal production practices, because the use of short residual pesticides and different chemical classes is often required for each respective crop in the rotation. However, in many perennial crops (tree, vines, alfalfa, etc.) and monoculture row crops (cotton, sugarcane, etc.), the crop pesticide history will play a significant role in trial site selection. 

For compounds applied to annual crops, another approach is to apply the compound to bare soil prior to crop emergence and follow the soil dissipation of the compound as the crop emerges and grows throughout its normal growing season.This is the appropriate use pattern for pre-emergence compounds and represents another approach that may used to study the soil dissipation of foliar-applied compounds. 

Other treatments have similar effects to those of early planting and include priming of true seed, presprouting of tubers as in potatoes and the use of transplants. Generally, there is some flexibility in the use of such treatments in annual crops but it may be limited by local agro-meteorological conditions or the need to deliver a crop to the market at a predetermined time. Of course, the limitations are even greater in perennial crops. 

However, there are differences between the various soil and climate types, the ways of utilisation and the crop species (Freibauer et al. 2004 Smith 2008). Depending on the species, the cultivation of annual crops causes a loss of 280-1,300 kg C ha-1 year-1, while grasslands and other conventional perennial crops do not cause a loss but a growth by 600-800 kg ha-1 year-1, and SRCs by even 400-1,600 kg ha-1 year1 because these fields are not tilled (Table 5.8). 

The coca leaf is either consumed by the natives of South America or exported to other countries for consumption. Another use of the coca leaf is in the extraction of cocaine either for illegitimate or legitimate use. The majority of the legal and/or clandestine cocaine factories are in South America due to the cost and bulk of transporting the whole leaf. In 1961, Bolivia produced an annual crop of from 12,000 to 18,000 tons of leaves although only half reached the legal market. The alkaloid cocaine is extracted from the coca leaf in basically three different chemical procedures. These procedures are used both in licit and illicit labs in the production of cocaine. 

Xylan occurs in practically all land plants and is said to be present in some marine algae.6 In both wide botanical distribution and abundance in nature it closely follows cellulose and starch. It is most abundant in annual crops, particularly in agricultural residues such as corn cobs, corn stalks, grain hulls and stems. Here it occurs in amounts ranging from 15 to 30%. Hard woods contain 20 to 25% xylan while soft woods contain 7 to 12 %. Spring wood has more pentosan than summer wood. 7 Low strength vegetable fibers of commerce such as jute, sisal, Manila... 

This problem of natural balance is, of course, less noticeable in annual crops of short season than in perennial tree crops, where the results of an unfortunate application may show up 9 months to a year later. Sometimes also this business of... 

The time-honored method of controlling insect-borne virus diseases is by breeding resistant varieties. This has been practical in annual crops, but is hopelessly slow in tree crops, where it may take 20 years or more to test a new variety. What is needed desperately is some sort of treatment which will control the virus, probably a systemic treatment, as the virus works within the plant cells. This is not a new idea and work has been done along this line by many workers. A sense of urgency is inevitable, however, when 500 to 600 acres of citrus can be wiped out completely in 3 to 5 years time, followed by an expensive replanting job and a wait of 5 to 6 years to get back into production. This is the outstanding problem at the present time and may need years to answer. 

Agriculmre, which is not only the largest water user, requires more water and this land use is also emerging as one of the main contributors to water pollution. Many subsistence farmers have benefited from the green revolution, which resulted in the introduction of multiple annual cropping cycles (up to four-crop rotations... 

The perennial plant can reuse certain organs every year, hence need not buQd them anew. Furthermore, perennials can usually produce a full flush of foUage more quickly than an annual plant, hence maximises photosynthetic gain early in the season—in contrast to the rapid canopy cover of a tree with the rate at which an annual crop such as wheat, potato or maize reaches full coverage. 

Clark, T. F. In Annual Crop Fibers and the Bamboos in Pulp and Paper... 

CTIC (1998). 17th Annual Crop Residue Management Survey Report. November. 

In the above example, the growing season is longer than the maturity period which results in simulated harvests occurring in Juty and in October. The sum of the fractions assigned to each harvest ( + 7) is equal to 1 which represents die total annual crop yield. 

Tree crop mainly based on the production of permanent crops, e.g. cocoa, coffee, oil palm or rubber. In the establishing phase, before shade impedes annual crop growth, food crops are interplanted and grown mainly for subsistence. 

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