Entitled Response of Apple rootstocks (MM.111, M.9, and MM.106) and Cultivars (‘Anna’ and ‘Jonagored’), to low Soil pH of Chencha,
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Date
2006
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Addis Ababa University
Abstract
Acid soils are severe problems in many parts of Ethiopia, especially on the highland areas of
the southern regions of the country. The coverage of acid soil of the country is estimated to be
about 40% of the landmass of which 15.6% is strong acid soil. It is generally known that acid
soils have adverse effects on growth and yield of apple trees. In view of the wide cultivation of
apple in southern Ethiopia, a study was conducted to assess the effect of naturally occurring
acidic soils and two low soil pH modified soils on three apple rootstocks (MM.111, MM.106,
and M.9) and two apple cultivars (‘Anna’ and ‘Jonagored’). The soil pH of the study site was
4.9; the pH was adjusted, down to pH 3.5 (in H2SO4) and higher to pH 6.3 (in lime). The
apple rootstocks were grown under these three pH treatments and studied for one year.
‘Anna’ and ‘Jonagored’ cultivars grafted on these three rootstocks under similar pH
treatments were also studied for three years. Data on vegetative growth and mineral content
of the different plant parts as well as yield components was followed. There were significant
growth differences between rootstocks. Under naturally occurring acidic soil (pH 4.9) the
vegetative growth of rootstocks were severely affected compared to soil pH of 6.3. Similarly,
strongly acidic soil of pH 3.5 severely decreased the growth of rootstocks in comparison with
pH 4.9 and 6.3. Among the three rootstocks, maximum vegetative growth were recorded for
MM.111 followed by M.9 whereas, least growth was registered for MM.106 in soil pH of 3.5.
The increase in growth was pH related. The effect of low pH on rootstocks elemental status
was significant. In soil pH of 3.5, MM.111 showed least concentration of Al in roots and Mn
in leaves and maximum amount of Ca, Mg, P and N in soil pH of 3.5 which makes it the most
the most tolerant of low pH followed by the rootstock M.9. On the other hand, least amount of
Ca, Mg, P, N and highest concentration of Al in the roots and Mn leaves was recorded for
MM.106which was the least resistant of the rootstocks. Under naturally occurring acidic soil (pH 4.9) both ‘Anna’ and ‘Jonagored’ cultivars grafted on MM.111, MM.106, and M.9
produced reduced vegetative growth, mean number of flowers and fruits compared to soil pH
of 6.3. ‘Anna’ and ‘Jonagored’ grafted on MM.111rootstock had the least growth with least
number of flowers and fruits were recorded on MM.106 in soil pH of 3.5. On the contrary,
both ‘Anna’ and ‘Jonagored’ grown on M.9 under soil pH of 6.3 produced more flower and
fruits followed by MM.106 and least was found on MM.111. Among the two cultivars, more
number of flowers and fruits were produced by ‘Anna’ than ‘Jonagored’. Rootstock type had
significant influence on scion leaf nutrient accumulation. The higher concentration of Al and
Mn was found in leaf of both ‘Anna’ and ‘Jonagored’ grafted on all three rootstocks under
naturally occurring acidic soil (pH 4.9) compared to soil pH of 6.3. In strongly acidic soil of
pH 3.5, the accumulation of Al and Mn in leaves of ‘Anna’ and ‘Jonagored’ grafted on
MM.106 was higher followed on M.9, and least was recorded on MM.111. Leaves of ‘Anna’
grown on MM.111 accumulated significantly higher concentration of macro-nutrients, Ca,
Mg, P, and N,all within the sufficiency range for macronutrients, while, on M.9and MM.106
the concentrations were all in the deficiency range. In contrast, nutrient absorption of
‘Jonagored’ was most efficient on MM.106 in uptake of Ca, Mg, P, and N, followed by M.9
and least on MM.111 under soil pH of 3.5. Similar findings were registered under pH of 4.9.
The study showed that the rootstock MM.111 is the most tolerant of acid soils and could be
used in the large acid soils of apple cultivating regions. The cultivars ‘Anna’ and
‘Jonagored’ grafted on MM.111 had the most tolerance of acid soils and least accumulation
of the deleterious Al and Mn in their tissues. The implications of the findings are discussed
and recommendations on future work suggested.
Key Words: apple, scion cultivars, rootstocks, growth, mineral content, pH levels.
Description
Keywords
apple, scion cultivars, rootstocks, growth, mineral content, pH levels