EFFECT OF SOME PEAR ROOTSTOCKS ON GROWTH, FRUITING AND RESISTANCE TO FIRE BLIGHT DISEASE OF "LE-CONTE" PEAR CULTIVAR

Document Type : Research articles.

Authors

1 Deciduous Fruit Dept. Hort. Res. Instit., Agric. Res. Centre, Giza-Egypt

2 Plant Pathol. Dept. Fac. of Agric., Ain Shams University

3 Plant Pathol. Res. Inst., Agric. Res. Centre, Giza-Egypt

Abstract

This study was carried out during 2012 and 2013 seasons on "LeConte" pear trees budded on four rootstocks namely, "Winter Nelis", "Pyrus
betulaefolia", "
Pyrus calleryana" and "Pyrus communis", planted at ElKanater Horticultural Research Station, Kalubeia governorate, Egyp. This
study was planned to evaluate the effect of these rootstocks on some
horticultural characters as well as resistance the fire blight disease of "LeConte" cultivar.
Trunk and shoot parameters of "Le-Conte" trees were lower on
"P.
communis"
and "Winter Nelis" rootstocks than those on "P. betulaefolia"
and "P. calleryana". Average numbers of spurs and average number of
flowers/spurs or/shoot were high on "
P. betulaefolia", moderate on "P.
communis"
and "P. calleryana" but low on "Winter Nelis".
Full Blooming date was early on "
P. betulaefolia" and "P.
calleryana"
(9–12 of March) which reflected on the production but late on
"
P. communis" and "Winter Nelis" (14–16 of March). Results cleared that,
"P. betulaefolia" and "P. communis" rootstocks were more productive for
"Le-Conte" cultivar than "
P. calleryana" and "Winter Nelis".
With respect of chemical fruit characters, TSS and TSS/acid ratio
were high and acidity was low on "
P. communis" and 'Winter Nelis", on the
other hand, TSS and TSS/acid ratio were low and acidity was high on "
P.
calleryana"
and "P. betulaefolia".
However, "
P. calleryana" and "P. betulaefolia" rootstocks under
nature infection conditions,
expressed resistance to fire blight disease but
"P. communis" and "Winter Nelis" expressed susceptibility in this respect.
There were a positive relationship between horticultural characters
and resistance of pear tree to fire blight disease. "
P. calleryana" and "P.
betulaefolia"
rootstocks as resistant were early in the flowering (9–12 of
March) and had vigorous tree growth as well as fruit juice has less TSS and
higher acidity. While "
P.communis" and "Winter Nelis" rootstocks as
susceptible to the disease were
lately flowering (14–16 of March) and had
week growth trees. as well as fruit juice has less acidity and higher TSS.

Hence, P. betulaefolia" and "P. calleryana" showed more
resistance to fire blight disease. However, "P. betulaefolia" is considered
better rootstock to "Le Conte" cv. than "P. calleryana" which susceptible to
lime-induced chlorosis.



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