Effect of in vitro raised plantlets of bitter gourd (Momordica charantia L.) lines to arbuscular mycorrhiza (AM) strains.
Authors: Swati Saha, T.K. Behera and S.K. Singh
Indian Agricultural Research Institute, New Delhi -110012

Tissue culture has tremendous impact on the crop improvement programme for rapid multiplication in different vegetable crops. However, large scale mortality of plantlets raised through tissue culture occurs during acclimatization phase (Stage IV), i.e. glasshouse and later at field transfer. Micropropagated plants are adversely affected by water stress, either due to low absorption capacity of their roots or due to stomata deficient regulation of water loss. Acclimatization of micropropagated plants corresponds to a transition period when roots become adapted to a substrate with less available nutrients, and to an autotrophic condition. At this stage, the presence of mycorrhizae could increase the availability of phosphorous (P) and nitrogen (N) through facilitating the absorption. Micropropagated plants develop under high moisture and low lighting conditions, often with low lignifications levels decreased functionality of the root systems that cause low survival rates to weaning. Arbuscular mycorrhizal fungi (AMF) have several advantages to plants including increased root area for absorption, enhanced uptake of nutrients, resistant to plant pathogens and drought. Moreover, it increases plant growth and nutrient content of plants growing in low nutrient soils.

To ameliorate this problem in bitter gourd, an attempt was made to use different arbuscular mycorrhizal (AM) strains, which could be inoculated to the roots of such plants to avoid the fungal attack especially those causing rots. Thirty-day-old, in vitro rooted plantlets of bitter gourd cultivars Pusa Do Mausami, Pusa Vishesh and the DBGy 201 were subjected to root colonization with arbuscular mycorrhizal (AMF) strains Acaulospora scorbiculata, Glomus manihotis, Scutellospora heterogama, Gigaspora gigantia, Entrophospora columbiana and Mixed strain (AMF) along with an uninoculated control. Mycorrhization plantlet showed increase in vine length in Pusa Vishesh in mixed strain, leaf area in Pusa Vishesh in Acaulospora scorbiculata, chlorophyll content in Pusa Do Mausami in A. scorbiculata and total phenol content in Pusa Do Mausami in E. columbiana). Photosynthetic rates were enhanced in arbuscular mycorrhizal fungi treated plant in Pusa Do Mausami in mixed strain in comparison to an uninoculated control. Among the AMF strains mixed strain (Nutrilink) showed good as high as 38% root colonization for all the cultivars. Though some of these strains did not give good colonization but drastically reduce the pathogen infestation. The Nutrilink has contributed significantly in survival of the plantlets and plant establishment in the field.

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