Leaf Photosynthesis, Leaf Permeability, Crop Growth, and Yield of Short Spring Wheat Genotypes Under Irrigation1
- R. A. Fischer,
- F. Bidinger,
- J. R. Syme and
- P. C. Wall2
Because of the expected importance of photosynthetic activity to yield, the relationships of leaf photosynthetic traits to crop growth rate and yield in 48 genotypes of spring wheat, were examined under irrigation in northwest Mexico. There were three tall and 33 short (Norin 10-derived) bread wheats (Triticum aestivum L.), eight short durum wheats (T. turgidum L.) and four triticales (X Tritosecale Wittmack). Photosynthetic activity (A) and leaf permeability viscous air flow (LP) were measured weekly using 14CO2, uptake and an air flow porometer, respectively.
Genotypic effects on A (range 14.7 to 20.4 mg CO2 dm-2 hour -1) and LP (range 5.7 to 11.1 permeability units) were highly significant but species effects were small and nonsignificant. Looking now exclusively at the short bread wheat group, A was unrelated to specific leaf weight or to LP. A on the first sampling at 4 weeks before anthesis and preanthesis crop growth rate (g -2 day-1) were weakly correlated (phenotypic r = 0.42, significant at the 0.05 level), and both these traits were positively correlated with mature plant height (r = 0.56, significant at the 0.01 level, and 0.68, significant at the 0.05 level, respectively). A was also positively correlated with crop growth rate during grain filling (r = 0.46, significant at the 0.01 level) and with yield (r = 0.45, significant at the 0.01 level; yield range 516 to 860 g m-2). These correlations arose because of the positive influence of days to anthesis on all three traits and probably reflect an increase in sink size (more kernels -z) with later anthesis. Yield was positively correlated with LP (r = 0.56, significant at the 0.01 level); the correlations remained significant (r = 0.46, significant at the 0.01 level) after allowance for the negative effect of plant height on both (LP was unrelated to anthesis date). While the cause of this correlation may be indirect, the testing of LP as an early generation selection criterion is suggested. Effects of major Norin 10 dwarfing genes on these relationships are discussed.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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