Agriculture Reference
In-Depth Information
TABLE 1.18
Examples of C
3
and C
4
Field Crops
C
3
Crops
C
4
Crops
Barley
Maize
Dry bean
Millet (pearl)
Cotton
Sorghum
Cowpea
Sugarcane
Oat
Peanut
Rice
Soybean
Sugarbeet
Wheat
Source:
Adapted from Fageria, N. K. 1992.
Maximizing Crop Yields
.
New York: Marcel Dekker; Fageria, N. K., V. C. Baligar, and
C. A. Jones. 2011a.
Growth and Mineral Nutrition of Field
Crops
, 3rd edition. Boca Raton: CRC Press. With permission.
Table 1.18 provides examples of C
3
and C
4
crops. The two types of photosynthetic pathways differ
in chloroplast arrangement, primary photosynthetic enzymes, temperature response, water-use effi-
ciency, light saturation, and response to CO
2
concentrations (Table 1.19). Mahon (1983) and Tanaka
and Osaki (1983) determined the photosynthetic rates per unit leaf area for some important field
crops (Table 1.20). No clear differences in photosynthetic rates exist among crop species, except for
maize, which has about two times higher photosynthetic rates than many other crops. Variation in
photosynthetic rates are often correlated with concentrations of nitrogenous compounds in leaves
(Evans, 1983; Hirose and Werger, 1987). This correlation is explained by the fact that some 75% of
all N in mesophyll cells of C
3
plants is associated with photosynthesis (Lambers, 1987). Further,
TABLE 1.19
Characteristics of C
3
and C
4
Plants
Characteristics
C
3
C
4
Photosynthetic efficiency
Low
High
Photorespiration
High
Low
Water utilization efficiency
Low
High
Optimum temperature for photosynthesis
10-25°C
30-45°C
Response to light intensity
Low
High
Response to CO
2
concentration
Low
High
Response to O
2
concentration
Low
High
Major pathway of photosynthetic CO
2
fixation
Reductive pentose
phosphate cycle
C
4
-dicarboxylic acid and reductive
pentose phosphate cycle
Transpiration ratios
High
Low
Leaf chlorophyll a to b ratio
Low
High
Source:
Adapted from Fageria, N. K. 1992.
Maximizing Crop Yields
. New York: Marcel Dekker; Fageria,
N. K., V. C. Baligar, and C. A. Jones. 2011a.
Growth and Mineral Nutrition of Field Crops
, 3rd
edition. Boca Raton: CRC Press. With permission.
