Papers by Seerjana Maharjan
Nepal Journal of Science and Technology, 2015
Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance whic... more Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance which is rapidly expanding in Nepal and other Asian countries with negative impacts on species diversity, health of human and livestock, and productivity of pasture and agriculture. To understand the invasive success of this weed, we analysed soil of its invaded sites, morphological traits, biomass allocation, leaf attributes, and phenology in the Kathmandu valley. The roadside soil, which is loamy sand in the valley is highly suitable for the growth and proliferation of the parthenium weed where its density has become double in less than a decade. An average size plant was 112 cm tall with 12 cm long tap root and produced 2637 achene per plant (max. 3865 per plant). A combination of different leaf traits enables the parthenium to grow under diverse habitats such as resouces poor condition (due to low specific leaf area, SLA), disturbed habitats (due to low leaf dry matter content, LDMC) as well as productive sites (due to high leaf nitrogen content). During rainy season it completes lifecycle in 16-18 weeks. Relatively long (12-16 weeks) reproductive period with high output of small seeds and their capacity to germinate and flower anytime in the year make parthenium a successful invasive weed in the Kathmandu valley.
Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance whic... more Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance which is rapidly expanding in Nepal and other Asian countries with negative impacts on species diversity, health of human and livestock, and productivity of pasture and agriculture. To understand the invasive success of this weed, we analysed soil of its invaded sites, morphological traits, biomass allocation, leaf attributes, and phenology in the Kathmandu valley. The roadside soil, which is loamy sand in the valley is highly suitable for the growth and proliferation of the parthenium weed where its density has become double in less than a decade. An average size plant was 112 cm tall with 12 cm long tap root and produced 2637 achene per plant (max. 3865 per plant). A combination of different leaf traits enables the parthenium to grow under diverse habitats such as resouces poor condition (due to low specific leaf area, SLA), disturbed habitats (due to low leaf dry matter content, LDMC) as well as productive sites (due to high leaf nitrogen content). During rainy season it completes lifecycle in 16-18 weeks. Relatively long (12-16 weeks) reproductive period with high output of small seeds and their capacity to germinate and flower anytime in the year make parthenium a successful invasive weed in the Kathmandu valley.
Scientific World, 2010
Allelopathic effects of aqueous extract of leaves of Parthenium hysterophorus were studied on see... more Allelopathic effects of aqueous extract of leaves of Parthenium hysterophorus were studied on seed germination and seedling growth of three cereal crops (Oryza sativa L., Zea mays L. and Triticum aestivum L.), three cultivated crucifers (Raphanus sativus L., Brassica campestris L. and Brassica oleracea L.) and two wild species of family Asteraceae (Artemisia dubia Wall ex. Besser and Ageratina adenophora (Spreng) King and HE Robins). Seed germination of all crucifer species was completely inhibited at >2% leaf extract of Parthenium hysterophorus but in other species, except maize, complete failure of seed germination was recorded only at >6% in Triticum aestivum and Ageratina adenophora; at 10% in Oryza sativa and Artemisia dubia. Seed germination of Zea mays was not completely inhibited but it was low at high concentration of the extract. The extract had strong inhibitory effect to root elongation of seedling in cereals and to shoot elongation in crucifers and wild Asteraceae. Leaves of Parthenium hysterophorus may be a source of natural weedicide against Ageratina adenophora which will help to control invasive plants.
Scientific World, 2010
Allelopathic effects of aqueous extract of leaves of Parthenium hysterophorus were studied on see... more Allelopathic effects of aqueous extract of leaves of Parthenium hysterophorus were studied on seed germination and seedling growth of three cereal crops (Oryza sativa L., Zea mays L. and Triticum aestivum L.), three cultivated crucifers (Raphanus sativus L., Brassica campestris L. and Brassica oleracea L.) and two wild species of family Asteraceae (Artemisia dubia Wall ex. Besser and Ageratina adenophora (Spreng) King and HE Robins). Seed germination of all crucifer species was completely inhibited at >2% leaf extract of Parthenium hysterophorus but in other species, except maize, complete failure of seed germination was recorded only at >6% in Triticum aestivum and Ageratina adenophora; at 10% in Oryza sativa and Artemisia dubia. Seed germination of Zea mays was not completely inhibited but it was low at high concentration of the extract. The extract had strong inhibitory effect to root elongation of seedling in cereals and to shoot elongation in crucifers and wild Asteraceae. Leaves of Parthenium hysterophorus may be a source of natural weedicide against Ageratina adenophora which will help to control invasive plants.
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Papers by Seerjana Maharjan