LIGHT PENETRATION AND LEAF PHOTOSYNTHESIS IN CANOPY OF TOMATO AND ARALIA CORDATA IN COMPARISON WITH WHEAT

F.F. Qin, F.L. Du, H.L. Xu, Q.C. Xu
Plant productivity is more closely related with the amount of canopy photosynthesis than with that of single leaf photosynthesis. A plant canopy is comprised of a population of leaves being exposed to different light intensities. The photosynthetic activity of a canopy is determined by the plant growth and leaf senescence, which is in turn determined by the canopy light penetration. In the present study, light penetration and leaf photosynthesis in canopy of tomato and Aralia cordata were compared with wheat. Light penetration into the canopy was measured and modeled by an exponential equation as
I/I0=[1-IB(1+βd)]I0e-αFd+IB(1+βd),
where I/I0 is relative value of the original PPF at a given canopy layer; IB is real PPF at the bottom of canopy; α is canopy light extinction coefficient; βis coefficient related with canopy PPF increase by reflected light; d is relative value of the depth in canopy; F is leaf area index. The PPF response curve was determined as
PN=PC(1-e-KI)-RD.
It was found that, inside a single stand (a row or bush), light penetration was worse in Aralia cordata and tomato with broad and large leaves than in wheat with small and narrow leaves, but in the whole field canopy, light penetration was better in the former than in the latter owing to large spaces between the rows in the former compared to the latter. Leaves at lower positions in Aralia cordata and tomato canopies used to extend toward the outside of the single canopy to receive the light in the space between rows or stands and consequently maintained less senescence compared with the wheat canopy. Even for the wheat, photosynthesis in lower leaves would be improved if the plants were grown in raised beds with a larger space between beds. Therefore, a proper arrangement by cultivation plan should be suggested to a specific crop.
Qin, F.F., Du, F.L., Xu, H.L. and Xu, Q.C. (2011). LIGHT PENETRATION AND LEAF PHOTOSYNTHESIS IN CANOPY OF TOMATO AND ARALIA CORDATA IN COMPARISON WITH WHEAT. Acta Hortic. 907, 355-358
DOI: 10.17660/ActaHortic.2011.907.58
https://doi.org/10.17660/ActaHortic.2011.907.58
light penetration, mathematic approach, photosynthesis, plant canopy, shift
English

Acta Horticulturae