Seed Germination Ecology of Feather Lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes]

PLOS ONE, Dec 2019

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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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. - 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)


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Bhagirath S. Chauhan. Seed Germination Ecology of Feather Lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes], PLOS ONE, 2013, 11, DOI: 10.1371/journal.pone.0079398