Plant Growth Responses to Vesiculararbuscular Mycorrhiza

Abstract

SUMMARYLight and temperature greatly influenced the development of vesicular-arbuscular mycorrhiza and growth of onions in a phosphate-deficient soil. There were more large arbuscules and host growth was stimulated more with 25,000 lux than with 13,000 lux at 23° C and in a 14-23° C diurnal cycle. At 14° C and 13,000 lux mycorrhiza caused no growth stimulation even in three low-phosphate soils. At 18° C infection was much sparser in a 6 h daylength than in 12 and 18 h. Mycorrhizal plants kept in daylengths of 6 h at 13,000 lux were 3.5 times heavier than their non-inoculated controls. The effect of infection increased in longer daylengths and higher light intensities to 14.2 times the weight of controls with 18 h at 25,000 lux. The addition of soluble phosphate stimulated growth to the same extent as mycorrhizal inoculation did in the highest light conditions but phosphate stimulated growth more than did mycorrhiza under intermediate light conditions. The amounts of soluble carbohydrate in the roots of plants given phosphate and in those that were mycorrhizal did not differ significantly, but there was more soluble carbohydrate in plants growing in most light. Plants both with and without mycorrhiza contained much glucose, fructose, sucrose and an unidentified sugar with a low RF value, but there was no indication of fungal carbohydrates such as trehalose and mannitol.

Effects of endomycorrhizal development and light regimes on the growth of Dicorynia guianensis Amshoff seedlings

“…Our results are consistent with many others found in the literature, which concern the benefits conferred by mycorrhizal colonization on the host plant [25,26]: mycorrhizal infection stimulated the growth of D. guianensis seedlings, and the intensity of the stimulation was clearly affected by light intensity. The extra dry matter production was greatest under medium light intensity, which also led to largest leaf area.…”

“…Since that time, many investigators have reported conflicting results [25,36,44]. Interactions between mycorrhizal efficacy and light are complex because light affects plant growth not only directly through photosynthesis, but also indirectly through its effects on other factors [12,21].…”

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

“…Nutrient status of soil is the best studied, commonly observed experimentally (e.g. Bjorkman, and probably the most relevant environmental 1942; Hayman, 1974;Daft & El Giahmi, 1978; Son mediator of plant responses to mycorrhizal associ-& Smith, 1988). Anthropogenic pollution can alter ations.…”

Successive cultivation of maize and agricultural practices on root colonization, number of spores and species of arbuscular mycorrhizal fungi

“…Soil pH is a factor that normally affects the development of mycorrhizal symbiosis (17,28,31), mainly at acidic levels when the soil presents high Al + and H + contents, which are toxic to AMF (26,30) and cause the adsorption of phosphorus, making it unavailable to the plant.…”