INFLUENCE OF SUBMERSION OF THE ROOTS ON TRANSPIRATION, APPARENT PHOTOSYNTHESIS, AND RESPIRATION OF YOUNG APPLE TREES

Abstract

The roots of young apple trees growing in soil in 5-gallon containers were submerged in water for a week to 2 months, then drained. Transpiration, apparent photosynthesis, and respiration were measured with the Heinicke-Hoffman apparatus, before, during and after submergence of the roots. Expts. were performed both in the field and in an environment control chamber. Transpiration and apparent photosynthesis were reduced within 2 to 29 days, usually within 2-7 days, after the roots were submerged; in some cases these rates became so small with continued submersion that they could not be measured. Apparent respiration was increased within 2 days after submerging the roots. When water was drained from the soil, the rate of respiration returned to near the pre-treat-ment rate. Leaf temp. and the behavior of stomata could not be correlated with low leaf activity due to root submergence. Leaves from submerged trees contained less water and ash per unit of leaf surface than leaves from check trees. Small apple roots were observed to die even under favorable soil conditions, but the development of new roots and formation of root hairs were inhibited by submergence.