Cultivars

Through genetic manipulation, com cultivars with altered starch compositions have been developed. Various modified and detivatized starches are... 

Enantiomeric distribution of y-lactone homologues from different apricot cultivars. Identification of dihydro-actinidiolide (co-eluted with y-Cl 1 on DB-1701)... 

The well-documented case of the United States serves as an illustration. During the period 1870 to 1900 the farm population was increased through a rapid expansion of the agricultural area. The agricultural labor force increased by 60 percent, but there was a replacement of labor by nonland capital in the form of horses and mules. New and more efficient types of horse-drawn machinery including plows, cultivars, seed drills, grain harvesters, and mowers became available. 

Early this century, differences in W were demonstrated among species and among cultivars within species (Briggs Shantz, 1914). These experiments simply involved measurements of plant dry weight and of pot weight. Although simple in concept, they are tedious to apply on the large scale that is required for selection by breeders (see Chapter 11). 

Fig. 5. Water-use efficiency (carbon basis) v. average carbon isotope discrimination in the whole plant, r= -0.88. Open symbols represent well-watered plants and closed symbols represent plants that were droughted. Tifton 8 A, Florunner A, VB187 and +, Chico are cultivars of peanut (Arachis hypogaea). (From Flubick etal., 1986).

Wright, G.C., Hubick, K.T. Farquhar, G.D. (1988). Discrimination in carbon isotopes of leaves correlates with water-use efficiency of field-grown peanut cultivars. Australian Journal of Plant Physiology, 15 (in press). 

Table 5. Solute contents of youngest emerged leaves of the amphidiploid, its parent and cultivar Ciano 79 grown for 30 days in non-saline and saline medium"... 

One of the metabolic responses of plants exposed to environmental stress is the production of proteins which may be qualitatively and/or quantitatively different from those produced in the absence of the stress (see Chapter 9 for general discussion). In some cases these responses have been found to depend on genotype for example, when a salt-tolerant cultivar and a salt-sensitive cultivar of barley were exposed to salt stress the shoot tissue responded by synthesising proteins which were cultivar specific. Five new proteins not found in the salt-sensitive barley were identified in the salt-tolerant cultivar (Ramagopal, 1987). No differences in proteins were found in the roots of either cultivar. 

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. 

Agarwal, P.K. Sinha, S.K. (1984). Effect of water stress on grain growth and assimilate partitioning in two cultivars of wheat contrasting in their yield stability in a drought-environment. Annals of Botany, 53, 329-40. 

Boyer, J.S., Johnson, R.R. Saupe, S.G. (1980). Afternoon water deficits and grain yields in old and new soybean cultivars. Agronomy Journal, 72, 981-6. 

Castleberry, R.M., Crum, C.W. Krull, C.F. (1984). Genetic yield improvement of U.S. maize cultivars under varying fertility and climatic environments. Crop Science, 24, 33-7. 

Fischer, R. A. Maurer, R. (1978). Drought Resistance in spring wheat cultivars. I. Grain yield responses. Australian Journal of Agricultural Research, 29, 897-905. 

Fischer, R.A. Wood, J.T. (1979). Drought resistance in spring wheat cultivars. III. Yield associations with morpho-physiological traits. Australian Journal of Agricultural Research, 30, 1001-11. 

Havaux, M. Lannoye, R. (1985). Drought resistance of hard wheat cultivars measured by a rapid chlorophyll fluorescence test. Journal of Agricultural Science, Cambridge, 104, 501-4. 

Keim, D.L. Kronstad, W.E. (1981). Drought response of winter wheat cultivars under field stress conditions. Crop Science, 21,11-15. 

Shpiler, L. Blum, A. (1986). Differential reaction of wheat cultivars to hot environments. Euphytica, 35, 483-492. 

Ponnamperuma, F.N. (1984). Role of cultivar tolerance in increasing rice production on saline lands. In Salinity Tolerance in Plants Strategies for Crop Improvement, ed. R.C. Staples and G.H. Toenniessen, pp. 255-71. New York John Wiley. 

Lebot, V. and Cabalion, P. 1986. Les Kavas de Vanuatu, (cultivars de Pipermethysticum Eorster). Coll. Trav. Doc. ORSTOM, Paris. 205 1-260. 

The range (p,g/100 fresh weight) of lycopene and P-carotene in selected tomato cultivars can be 20-62000 and 35-2200 respectively, and of P-carotene and a-carotene in selected carrot cultivars 1100-64000 and 530-36000 respectively. Some of the carotenoids may be present as fatty acid esters (Breithaupt and Bamedi, 2001). More extensive listings can be found (O Neill et al, 2001 van den Berg et al, 2000 Hart and Scott 1995). 

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