rice is considered to be the most troublesome weed in European
rice fields. Last year in these cultivation areas, the weed spread
more widely, particularly after the diffusion of less competitive
cultivated varieties. In these conditions, weed infestations have
been favoured by the use of rice seed polluted by grains of wild
plants and because of the lack of a successful means of control.
Rice growers are often induced to rotate rice with other crops,
but in most situations saline and hydromorphic soils severely
limit this option.
project proposal originates from the pressing need to find effective
and environmentally friendly methods of managing the spread of
this weed. The importance of this research has also been stressed
by the Concerted Action - EC-DG AGRI (n° AIR3-PL93-2518 -
Quality and Competitiveness of European Rices).
particular, this research project has the following aims:
to characterise and identify red rice biotypes, through molecular
markers, and to assess their relations to the crop as well as
their ability to be a weed;
to find simple diagnostic tests for red rice grain identification
in rice seeds;
to evaluate the competitiveness of the most popular cultivated
rice varieties with main red rice biotypes, in different culture
to study red rice population dynamics according to different environmental
and agronomical conditions;
to assess the emergence of red rice in relation to a tillage system,
straw and water management;
to test the effectiveness of mechanical and chemical means against
red rice, before and after rice planting and in rotational crops;
to develop and test strategies of integrated weed management,
based on the findings of studies on the biology, and the results
of specific control measures.
objectives will be pursued by:
characterising red rice biotypes using molecular markers;
studying biological red rice behaviour;
carrying out an inventory of and evaluating measures of weed control;
testing the combination of agronomical practices and direct and
indirect control measures giving the best sustainable management
of the weed.
results of the proposed research will provide substantial benefits
from a scientific, technical and environmental point of view.
research fits with the objectives of the FAIR work programme (areas
4.1.1-4.1.2-4.4.1) and with the policies of EU regulation 2078/92
(agri-environmental measures) in the area of the weed management.
1998, the project participants carried out a research activity
on the following four programmed tasks:
characterisation of red rice biotypes using molecular markers;
study of red rice biology;
evaluation of red rice control techniques;
integrated red rice management.
1. Characterisation of red rice biotypes using molecular markers
of weed characteristics has been studied by the use of Doubled
Haploid (DH) population. The DH lines have been characterised
to score the segregation of morphological traits related to weed
behaviour: seedling vigour, anthocyan pigmentation, tillering
ability, plant morphology, awning etc. All traits were significantly
different between the parents.
of the two parental lines has permitted detection of a high level
of polymorphism, though parental lines belong to temperate japonica
subspecies. Therefore, genetic mapping was considered in spite
of the genetic closeness of the two parental lines.
SSRs showing polymorphism on parental survey were mapped into
Kruskall-Wallis test was performed using Map Quantitative Traits
Loci (QTL) 2.4. A significance threshold of p0.01 was used to
identify QTL. A total of 18 QTLs for traits were identified and
located on seven chromosomes. Most of the QTLs identified for
weed characteristics were closely linked on chromosomes 1, 3,
7, 8 and 9.
were also started on organising the collection of red rice seeds
in the participants' main cultivation areas. These seeds will
be characterised both in relation to their phenological and genetic
2. Study of the red rice biology.
studies have been carried out in Italy, Portugal and Greece to
determine dormancy, seed longevity, depth of emergence and time
required by the seeds after flowering to become viable.
were carried out to study the competitive ability of the most
important rice varieties against red rice, at 2 N rate and 4 densities
of the weed. This research showed that shattering is related to
genetic features, and is only slightly influenced by agronomical
and environmental conditions, such as N supply and condition of
competition. The results showed that a weed density of 40 plants/m2
resulted in a yield reduction of about 40%.
experiments, started in 1997, and continued in 1998 in Italy and
Spain, showed that certified seed without red rice grains determined
the emergence of about 1 plant/1000m2 .
3. Evaluation of red rice control techniques
in all countries continued the experiments started in 1997 to
compare old and new direct mechanical and chemical methods of
weed control, to screen the more suitable means against this weed
in practical conditions of cultivation.
pre-emergence of the weed, the best herbicides were dimethenamid,
pretilachlor, acetochlor and alachlor. In post-emergence of the
weed, good results were obtained applying the false seeding technique,
combined with dalapon or quizalofop treatment, before rice planting.
Minimum tillage and water-saturated soil determined the greatest
number of emergences.
crop post-emergence, panicle cutting (with two interventions)
provided efficient prevention of weed dissemination.
3 (CFR, subpartner INRA) carried out a study aimed at identifying
all farmers' red rice control strategies applied in Camargue rice
fields. The survey showed that about 35% of the farmers controlled
red rice by chemical means, and 16% by crop rotation.
and French partners also carried out research to assess the effects
on red rice spread in these rotational conditions. After 1 year
of soyabean cultivation, the weed seed bank was reduced by 90%.
4. Integrated red rice management
order to assess the best systems of red rice management, both
in rotational crops and in rice in monoculture, several experiments
were carried out in all the project partners' countries.
results showed that all crop rotation systems (corn, soybean,
soybean with minimum tillage and delayed crop planting) associated
with appropriate herbicide application, were able to assure outstanding
red rice control.
all countries, experiments were carried out in rice monoculture
based on the most rational combination of control techniques applied
in pre- and post-emergence of the weed.
results were obtained:
in highly infested fields - applying the false seeding technique,
performed with minimum tillage followed by a dalapon treatment;
in less infested fields - simply adopting ploughing, which reduced
red rice emergence remarkably.
degli Studi di Torino
di Agronomia, Selvicoltura e Gestione des Territorio
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Aristotelian University of Thessaloniki
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