Role of arbuscular mycorrhizal fungus (Glomus intraradices Schenck and Smith) colonization in drought tolerance of maize (Zea mays L.).
|Title:||Role of arbuscular mycorrhizal fungus (Glomus intraradices Schenck and Smith) colonization in drought tolerance of maize (Zea mays L.).|
|Authors:||Subramanian, Kizhaeral S.|
|Abstract:||The purpose of this thesis was to study the potential factors involved in mycorrhizae-assisted drought tolerance in maize (Zea mays L.). We hypothesized that the AM colonization promotes drought tolerance of the host plant. This may be as a consequence of altered water relations, metabolism or nutritional status of the host plant. These changes enable the host plant to sustain water deficit conditions and recover more rapidly when irrigation is restored. To test these hypotheses, the five objectives were: (i) To measure the physiological responses in maize plants in the absence or presence of AM colonization; (ii) To examine the metabolic changes in these plants; (iii) To determine the host plant nutritional status in order to assess the ability of AM plants to support kernel development; (iv) To evaluate the drought recovery of maize and (v) To examine the effects of AM colonization on nitrogen assimilation in maize as a potential factor in drought tolerance. The AM colonization in maize had a beneficial effect on the water relations and leaf enlargement under water deficit conditions. In comparison to non-AM plants, the AM colonized plants maintained higher (less negative) leaf water potential (LWP) and lower stomatal resistance even after 3 wks of withholding water at the tasselling stage. Mycorrhizal colonization improved the nutritional status of maize through the enhanced uptake of N, P and other micronutrients. This indirectly helps the AM plants to utilize the soil available moisture more effectively. Our data indicated that the total N content in drought-stressed maize plants were nearly doubled in the presence of AM association. The overall results support the hypothesis that the AM colonization assists the two tropical maize cultivars to withstand under moderate drought conditions. The drought tolerance was achieved due to the physiological, metabolic and nutritional modifications in the host plant. These changes can be primarily related to the improved host plant water relations and the nutritional status, especially N and P. This thesis has provided new insights into the changes in N acquisition and assimilation of mycorrhizal plants under drought conditions. The findings of this thesis support the idea that AM fungi are one of the major biological components in the rhizosphere needed to accomplish the goal of sustainable agriculture in arid and semiarid areas. (Abstract shortened by UMI.)|
|Collection||Thèses, 1910 - 2010 // Theses, 1910 - 2010|