Mycorrhizal biotechnology has been used in rehabilating degraded sites because mycorrhiza enables the plants to
(1). resist drought and increase absorptive area
(2). tolerate extremes of pH
(3). resist disease infestation
Select the correct answer using the codes given below.
Answer:
(d)
CA
Re-introduction of Arbuscular Mycorrhizal Fungi into agricultural soils has been shown to increase crop yields in nutrient poor soils, increase yields for agricultural plants that have large requirement for nutrients and water, and restore structure and fertility to degraded soils. The resulting soil structure allows air and water movement into the soil, encouraging root growth and distribution, allows intra-aggregate organic matter to be slowly decomposed by microbes and converted into plant-available nutrients, and makes the soil less susceptible to wind and water erosion. Option-2:- Anthropogenic deposition increases the possibility of phosphorus (P) limiting productivity in forest ecosystems. Moreover, inorganic P availability is largely controlled by soil pH and biogeochemical theory suggests that forests with acidic soils (i.e., <pH 5) are particularly vulnerable to P limitation. Results from previous studies in these systems are mixed with evidence both for and against P limitation. Shifts in mycorrhizal colonization and community structure help temperate forest ecosystems overcome an underlying P limitation by accessing mineral and organic P sources that are otherwise unavailable for direct plant uptake. Option-3:- Vesicular-arbuscular mycorrhizae (VAM) enhance plant growth through increased nutrient uptake, stress tolerance and disease resistance. As an integral part of the root system, they interact with other microorganisms in soil and result in increased root exudation approaching about 25% of the plant dry matter production. Roots support a multitude of microorganisms that, in concert, can have profound influence on growth and survival of the plant. VAM fungi can alter the root exudation pattern, enhance chitinolytic activity and alter photosynthetic/respiratory deficiencies. VAM-positive plants are known to exhibit varied resistance towards soil-borne and foliar pathogens. The known interactions include a number of mechanisms, such as exclusion of the pathogen, lignification of plant cell walls, changed phosphate nutrition resulting in altered exudation by roots, and formation of inhibitory low molecular weight compounds