Cultivars studied

For those sweet potato cultivars studied, the crude protein (N x 6.25) contains both protein and nonprotein nitrogen (NPN). 

Horigome et al. (3J5) reported a PER of 1.9 for protein recovered from an industrial sweet potato starch facility. They were able to increase the PER to 2.5 by supplementing the diets with lysine and methionine. A portion of these amino acids were either destroyed or made biologically nonavailable by the processing operation. The possibility also exists that these amino acids were limiting in the cultivars studied. 

Cantos, E., Espin, J., and Tomas-Barberan, F., Varietal differences among the polyphenol profiles of seven table grape cultivars studied by LC-DAD-MS-MS. J. Agric. Food Chem. 50, 5691, 2002. 

More recently, static headspace GC analysis of eight cultivars of melons detected esters as the major volatile components. Differences among the compositions of the volatiles of the cultivars studied were also reported and are probably due to different efficiencies of biosynthetic pathways of each variety [56]. 

The vitamin A content of orange juice as given by Adams (35) is about 200 International units of provitamin A in 100 g. In more recent studies (Table II) (49), orange juice was found to have the least amount of provitamin A whereas Murcott (a reputed tangor) had the highest of the seven cultivar studies. The lowest found was in the Hamlin orange with 80 International units/6 oz of juice. The highest was Murcott with 3195 International units/6 oz of juice. All samples were taken from mature fruit except Valencia. When mature, Valencia juice normally contains more provitamin A than Hamlin or Pineapple juice. 

Since 1889, improved grass and cereal cultivars have been bred.41 It is difficult, and may be commercially impossible, to obtain viable seeds of cultivars required for studies extending over several years, as the cultivar may meanwhile have been replaced by another. For this reason, it may not be possible to re-examine the hemicelluloses of a cereal or grass cultivar studied earlier. 

Masa, A., Vilanova, M., Pomar, F. (2007). Varietal differences among the flavonoid profile of white grape cultivars studied by high performance liquid chromatography. /. Chromatogr. A 1164, 291-297. 

In a later study, Chun et al. [29] observed significant differences in tocopherol contents among seedling. Desirable, Stuart, and Schley cultivars. Crop year variations in total tocopherol were small and no statistical differences (P > 0.05) existed for y-tocopherol between crop years for each cul-tivar. Since y-tocopherol comprised over 90% of the total tocopherol fraction by weight in each cultivar studied, its presence at nonvariable levels constitutes an important antioxidant characteristic of the pecan. A summary of the Chun et al. [29] study is given in Table 16.7. 

For the cultivars studied, phytic acid was found to be concentrated in the outermost layer. Zinc distribution, on the other hand, was similar for three cultivars and was characterized by an even distribution throughout the kernel, with the exception of a higher concentration in the embryo. Studies of this nature will be valuable for optimizing the milling process for maximum removal of phytic acid with minimum mineral and yield loss and appropriate whiteness to satisfy consumer expectations for white rice. 

Relative peak area of aldehydes in pea cultivars grown in different locations and crop years is presented in Fig. 3. The mean value of aldehydes was significantly (P < 0.01) affected by the type of cultivar. However, no significant (P > 0.05) differences in aldehydes were observed between cultivars grown in different locations (Tables 2 4). 3-Methyl butanal was the most abxmdant aldehyde in all the pea cultivars studied (Tables 2 4). 

Fig. 4 shows relative peak areas of ketones in the different pea cultivars studied. A significant difference (P < 0.01) in the mean value of ketones was observed between pea cultivars from different locations (Tables 2 4). Pea cultivar grown in MPK had higher mean value of ketones compared to those from WIL (Table 2). In the 2009 crop year, pea cultivar grown in WIL had higher mean value of ketones than those from MPK (Table 4). 2-Butanone had higher mean value compared to 2-pentanone in all the pea cultivars studied (Tables 2 4). 

All three sample preparation techniques were suitable for characterizing the two cultivars. With all three methods, the relative peak areas of the aroma volatiles hexanal and 2-isobutylthiazole differed significantly for the two cultivars studied. Krumbein and Ulrich concluded that SPME is a suitable screening method for tomato fiavor. 

The literature is less extensive on the use of protoplasts in stress-tolerance investigations however, some applications have been attempted. For example, in one study protoplasts were isolated from the leaves of a wild relative of tomato shown to be salt tolerant and from a salt-sensitive, cultivated species (Rosen Tal, 1981). In the presence of NaCI the plating efficiency (number of surviving cells/number of cells applied to the plate) of the wild relative was greater than the cultivated, sensitive cultivar. Proline, when added to the culture media, was found to enhance the plating efficiency of the salt-sensitive cultivar but not the wild, salt-tolerant relative. These results suggest that traits related to salt tolerance are expressed by the isolated protoplasts and that the response of protoplasts to environmental stress can be manipulated, i.e. the proline response. 

Some cultivars of sweet potatoes for human consumption are also good sources of P-carotene since their contents can achieve 218 pg/g as in cultivar Acadian (Table 4.2.1). Although separation of cis isomers was not carried out in the later study, small amounts of 13-c -p-carotene were found in fresh sweet potatoes of an unspecified cultivar, whereas no cis isomers of P-carotene were found in this fresh vegetable in other studies. ... 

Gross differences have been ob.served in the amounts of fixed carbon released by annuals and perennials (47), with annuals releasing much less C than perennials. This effect may in part be due to perennials having to invest more of their assimilates to survive year round. Between more closely related plants, several studies have reported that both the quantity and quality of root exudates vary between plant species (39,48,49). In addition, it is also recognized that different cultivars of the same species may vary in their root exudation patterns. For example, Cieslinski et al. (50) quantified low-molecular-weight organic acids released... 

Beyrouty CA, Norman RJ, Wells BR, Flanson MG, Gbur EE. Shoot and root growth of eight rice cultivars. In Wells BR, editor. Arkansas Rice Research Studies 1992. Fayetteville Arkansas Agric. Expt. Stat. Res. Ser. 431 1993. pp. 119-122. 

Smartt AD, Rogers CW, Brye KR, Norman RJ, Smartt WJ, Hardke JT, Frizzell DL, Casteneda-Gonzalez E. Growing-season methane fluxes and emissions from a silt-loam soil as influenced by rice cultivar. In Norman RJ, Moldenhauer KAK, editors. B.R. Wells Rice Research Studies, 2014. Fayetteville Arkansas Agric. Expt. Stn. Res. Ser. 62 2015. pp. 289-297. 

There are several studies on the effect of fertilization on product composition. However, they were of limited scope because they do not provide clear answers on the effect of farming systems on composition. Bourn and Prescott (2002) made a comprehensive review on this subject and, overall, the studies suggested that the use of organic fertilizers may result in lower nitrate concentration for some crops and some cultivars than when using more soluble mineral fertilizers. Based on the observed large variations, they emphasized the strong influence of climatic conditions on nitrogen, nitrate and mineral content, as well as fertilizer treatments. 

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