عنوان مقاله [English]
Stomata are closed by moisture stress, reducing carbon assimilation and yield production with dry land agriculture. Relative 13C to 12C molar ratio assimilation by a plant is a function of time stomata remain open during plant life time, itself a function of moisture stress. The purpose of this study was to test the existence of any relationship between stomatal conductance and assimilation rate and final yield of treatment. The field experiment was established in Why College Estate, Kent, England. Employing the repeated measures method for statical analysis suggests no significant differences between subjects and no significant time interaction effects, The only significant subject was time effect itself (P=0.0001), suggesting an increasing Delta value for maize as a consequence of age and consequently accumulation carbon dioxide in crop. Although the extra yield production by heavy mulch and incorporation could be attributed to their extra canopy production (ground cover), the extra yield by light mulch with the same canopy cover as control and ammonium nitrate fertilizer (compost mulch treatment, at 100 t/ha versus compost incorporation treatment, at 50 t/ha) requires greater rates of carbon dioxide assimilation, which in this experiment is not attribute to the Delta value and hence stomotal conductance, (i.e. other unknown physiological processes might enhance carbon assimilation without affecting stomotal conductance). If the result from carbon discrimination in this experiment are reliable, they elude other factors involved in carbon dioxide assimilation rather than stomotal conductance.