Efecto de la sequía en la relación simbiótica entre Pinus pseudostrobus y Pisolithus tinctorius

Abstract

In heavily degraded soils moisture retention is deficient, causing drought conditions and consequently limiting plant growth. Symbiotic associations such as mycorrhiza might have a positive effect in the host plant in terms of nutrient uptake and possibly for drought resistance. To test the effect of the fungi under drought conditions, an assay was established with the ectomycorrhizal fungus Pisolithus tinctorius with Pinus pseudostrobus, with six treatments, three watering levels (every 3,7, and 14 days) and presence/absence of inoculation. Plant survival was evaluated through generalized linear models and Cox proportional hazard test and shoot and root growth through analysis of variance. We found significant differences in survival among treatments (?2(5)=197.93 y P<0.0001). The Cox test indicates that significant differences occur from the fifth month, when the highest mortality occurs in non-inoculated plants. At the end of the experiment, when plant where watered every three days survival was 100 [%], when watered every 7 days, 90 [%] for inoculated plants and 35 [%] for non-inoculated plants; when watered every 14 days all noninoculated plants died and 30 [%] of the inoculated plants survived. In terms of growth variables, statistical differences (P<0.0001) where detected among drought treatments, plants in symbiosis with P. tinctorius were able to ameliorate extreme drought effects. These results show the relevance of the micorrhizal interaction for drought tolerance in plants.