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Qin F.,University of Tokyo | Qin F.,International Nature Farming Research Center | Qin F.,Shandong Research Peanut Institute | Takano T.,University of Tokyo | And 2 more authors.
Journal of Food, Agriculture and Environment | Year: 2012

Previous research has shown that AnM (including exposing hypocotyl) and the modified AnM (AnM combined with film mulching) techniques improve photosynthesis (P N), plant growth and the final shell yield in peanut crops. Improvement in P N was attributed at least in part to increases in stomatal conductance (g S). Moreover, g S often oscillates in response to environmental changes. In the present experiment, the effects of the modified AnM technique on the stomatal oscillations were clarified. For the intact leaves of peanut plants, a modified equation from the cosine function showing the cyclic P N or g S oscillations under a given PPF was developed as follows: P N= [P A+P Acos(ωt+τ)](1+αt)+P R(1+βt) or g S= [g A+g Acos(ωt+τ)](1+αt)+g R(1+βt), where P A or g A is the amplitude of P N or g S; P R or g R is the residual value of P N or g S at the first oscillation bottom; t is the time; ω is the angular frequency; τ is the time needed for P N to move into the oscillation process; α is the constant related to the decay of the oscillation cycles; β is the constant related to the dynamic change of P R or g S. Oscillations also occur in the excised leaves during the leaf transpiration was declining and a modified model was used as P N= [exp(-α Pt)]{P A+P Acos[ω P(t-τ P)]}+P R(1-β Pt) or g s= [exp(-α st)]{g A+g Acos[ω s(t- τ s)]}+g R(1-β st), where P A or g A is the amplitude of the first oscillation after P N or g S starts decaying; α is the constant related to the decay of the exponential and oscillation cycles. Results of analysis showed that stomata oscillate with higher amplitude and shorter period in peanut plants in AnM plots than in control plots. During the transpiration declining in the excised leaves, oscillations of g S or P N were found in the excised leaves but were not clear in CK plots. The water retention ability was higher in the excised leaves from AnM plots than those from CK plots. In conclusion, peanut plants grown with the modified technique could prevent leaf water loss by controlling the stomatal opening and closing regularly.

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