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Wheat Information
Service
Number 72: 25-29 (1991)
Studies
on varietal mixtures in wheat
S. S. Bisht and B. S. Malik
Wheat Project Directorate, Indian Agricultural Research
Institute, New Delhi- 110 012,India
Summary
A study with varietal mixtures of most promising wheat varieties
of Northern India was undertaken to assess yielding potential and
rust severity. Varietal mixture of varieties of good fertility
irrigated conditions, low fertility rainfed conditions and a mixture
of varieties belonging to both these two crop production conditions
were composed to study the above two facts. It was observed that
mixtures were not superior than the best adapted genotype. However,
the mean yield of mixture was higher than the component mean. Yield
advantage up to 14.2 per cent was recorded in mixture composited from
varieties belonging to rainfed conditions. A variety in individual
stand showed high incidence of rust but the same when grown as a part
of mixture the rust incidence and severity is reduced.
Introduction
Pure line varieties of wheat suffer from disease as soon as new
virulences in pathogen are evolved. There is always risk in
cultivation of such varieties on commercial scale. Multilineal
varieties and variental blends have been advocated to minimise yield
losses due to parasitic fungi. Under these approaches the pathogen is
allowed to propagate on some of the components of multilines/varietal
mixture. Susceptible components when grown as a part of varietal
mixture suffered less from rust damage (Suneson1960; Borlaug1958;
Jensen and Kent1963) and there had been reported yield advantages of
varietal mixture (Jensen1965; Pandey et al 1978; Gill et al 1981).
Varietal mixtures have shown stable yield than the pure varieties
(Marshall and Brown1973).
The work on varietal blends of similar height, different height and
of different maturity group has resulted in considerable superiorty
of mixture for yield and lowering of disease severity. In the present
study varietal mixture from varieties of two different crop
production conditions i.e. irrigated and rainfed were studied in
respect of their yield performance and rust severity.
Materials and Methods
The materials for the present study comprised of 10 most popular
wheat varieties, HD 2177, HD 2122, HD 2204, WL 711, WH 147, HD 2009,
Kalyansona (irrigated conditions) WL 410, IWP 72 and HD 1981 (rainfed
conditions). Three multilines and three varietal mixture composed
from these varieties. These varietal mixture were consituted as
follows:
Mixture-A. Constituted from 7 wheat varieties suitable for
cultivation under highly fertile irrigated conditions.
Mixture-B. Constituted from 3 wheat varieties suitable for
cultivation under rainfed condition.
Mixture-C. Constituted from all the ten varieties of two different
crop production condition.
Yield potential of the varieties and mixtures was studied in a
randomised block design for two subsequent crop seasons i.e. 1978-79
and 1979-80 at IARI, New Delhi. In these experiments there were four
replications and grain yield was harvested from a plot of 5.0 x
0.92m. Rust data was recorded on modified Cobb's scale and the
observation were taken on three different dates of one week interval.
Height reading of incidence and severity of infection was utilised in
making conclusion. Yield data of individual years was analysed
statistically.
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