Seed Germination Ecology of Feather Lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes]
Citation: Chauhan BS (
Seed Germination Ecology of Feather Lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes]
Bhagirath S. Chauhan 0
0 Weed Scientist, Crop and Environmental Sciences Division, International Rice Research Institute , Los Banos, Metro Manila , Philippines
Feather lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes] is a C4 grass weed that has the ability to grow in both lowland and upland conditions. Experiments were conducted in the laboratory and screenhouse to evaluate the effect of environmental factors on germination, emergence, and growth of this weed species. Germination in the light/dark regime was higher at alternating day/night temperatures of 30/20 C (98%) than at 35/25 C (83%) or 25/15 C (62%). Germination was completely inhibited by darkness. The osmotic potential and sodium chloride concentrations required for 50% inhibition of maximum germination were -0.7 MPa and 76 mM, respectively. The highest seedling emergence (69%) was observed from the seeds sown on the soil surface and no seedlings emerged from seeds buried at depths of 0.5 cm or more. The use of residue as mulches significantly reduced the emergence and biomass of feather lovegrass seedlings. A residue amount of 0.5 t ha-1 was needed to suppress 50% of the maximum seedlings. Because germination was strongly stimulated by light and seedling emergence was the highest for the seeds sown on the soil surface, feather lovegrass is likely to become a problematic weed in zero-till systems. The knowledge gained from this study could help in developing effective and sustainable weed management strategies.
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Rice is an important crop in Asia, particularly in the
Philippines, where it is mainly grown by transplanting of
seedlings in ponded conditions. Because of labor and water
scarcities, however, this method of rice establishment is being
replaced by direct seeding of rice [1,2]. The spread of direct
seeding and the repeated use of herbicides with a similar mode
of action are shifting weed species populations in this rice
ecosystem [3]. Eragrostis species are examples of such weed
species that are increasing in direct-seeded rice systems and
there are reports that these species are less affected by
bispyribac-sodium, a common herbicide used as
postemergence in Asia [4,5]. Bispyribac is an acetolactate
synthase inhibitor, which can reduce the transport of
photosynthate from source leaves to roots.
Feather lovegrass is one of the Eragrostis species that was
reported to occur in dry-seeded and transplanting rice cultures
in India and Thailand [6]. It is a common weed in upland rice in
India, Indonesia, the Philippines, Thailand, and Vietnam [7]. In
the Philippines, it has been reported as a common weed in
both upland and lowland conditions [6]. Feather lovegrass is a
C4 grass species, which occurs not only in crops but also in
waste places, old walls, lawns, roadsides, beach dikes, and
gardens [7]. It is a prolific seed producer and one plant can
produce up to 140,000 seeds [8]. In addition, the weed is an
alternate host for nematodes, viruses, and insects [7].
Despite the importance of this weed in different rice
ecosystems, very little is known of its seed biology. The
development of effective and sustainable weed management
strategies depends on a detailed knowledge of weed seed
biology [9,10]. Seed germination and seedling emergence of a
weed species may be influenced by environmental factors,
such as temperature, light, soil salinity, soil moisture, soil burial
depth, and amount of crop residue present in the field. Light,
for example, is one of the most significant ecological
determinates for germination [11]. Seeds of weed species that
require light for germination will germinate only when present
on or near the soil surface. Such information and knowledge on
seedling emergence at various burial depths could help in
deciding on tillage systems to reduce emerging weed
seedlings. Similarly, the use of crop residue in conservation
agriculture systems may suppress the emergence of some
weed species [12-14]. The response of weed seedling
emergence to crop residue amounts may help to integrate
different weed management components. In many Asian
countries, rice is commonly grown in salt-affected and
droughtprone areas, and the weed flora in these areas is often
different. Information on the effect of salt and water stress on
the germination of feather lovegrass could help predict the
invasion potential of this species in such areas. A computer
search of the available literature revealed no such information
on lovegrass.
A study was designed to determine the effects of
temperature and light, salt and water stress, seed burial depth,
and rice residue on the germination and emergence of feather
lovegrass.
Materials and Methods
Seed collection and germination test
Seeds of feather lovegrass were collected in December 2012
from rice fields at the International Rice Research Institute, Los
Baos, (...truncated)