Biochemical characterization of drought tolerant and susceptible young maize plants under well-watered conditions
1997
Pena-Valdivia, C.B. | Raya P, J.C. | Perales Rivera, H. | Lotina H, B. | Merchant, R.
Selected biochemical traits were evaluated in various sections of developing leaves of a drought susceptible population, Tuxpeno Sequia C0, and of a drought-tolerant selection from the same population, Tuxpeno Sequia C8. Both populations were grown in the greenhouse under full sunlight and well-watered conditions. Photosynthetic and transpiration rates, a and b chlorophyll content, total protein, dry matter and specific weight were measured in five 2 cm sections along the second leaf when it was 10 cm long. Chloroplasts from mesophyll cells were also isolated from each section and photochemical activities were measured. Finally, ultrastructure organization of the chloroplasts in leaf tissue was observed by electron microscopy. Tuxpeno Sequia C8 had a higher photosynthetic rate (30 Per cent), accumulated more dry matter per leaf segment (5 Per cent), and had a higher specific leaf weight (10.5 Per cent) than C0. Although total protein and chlorophyll a contents were similar in both populations, C8 had 19 Per cent less chlorophyll b. With respect to photochemical activities of isolated chloroplasts, values for proton pumping, photophosphorylation and basal phosphorylating and uncoupled electron transport rates were 60 to 80 Per cent lower in C8 than in C0. Electron microscopy showed that chloroplasts of both blundle sheath and mesophyll cells differed somewhat morphologically between the populations.
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