Effect of Flooding on the Growth and Some Physiological Changes of Young Apple Rootstocks

Abstract

Effects of flooding on the growth and some other physiological changes were examined with 8 apple rootstocks (M27, M9, M26, M7, MM106, M11, M16 and Malus prunifolia; weeping type).
1-year-old pot grown rootstocks (propagated by either root cutting or layering) were flooded by immersing the pots in water to several centimeters above the soil surface for 30 days in a plastic greenhouse at the growing season in 1980 and 1981.
Flooding reduced stem growth of all rootstocks, but the degree varied greatly among rootstocks. M9, the least tolerant to flooding, ceased growth and showed leaf symptoms of injury after about 10 days of flooding, while the growth of M. prunifolia, the most tolerant, was somewhat decreased, but no leaf symptoms of injury were observed throughout the flooding period. Leaf injury due to flooding was slight with M27, M7 and M16, but considerable with M26, MM106 and M11. Root activity judged from TTC redution was greatly reduced by flooding with M9, MM106 and M26, but unaffected with M. prunifolia. Total phenol content was also decreased greatly for M9 but only slightly for M. prunifolia. Roots of M9 accumulated large amounts of ethanol after 10 to 20 days of flooding. Flooding increased leaf diffusion resistance, especially with M9, M26 and MM106. Leaf contents of N, P, K, Ca and Mg were significantly reduced in all rootstocks by flooding.
In conclusion, flooding tolerance of the rootstocks tested can be ranked in the descending order as follows: M. prunifolia>M16, M7>M27>M11>MM106> M26>M9.