Grain Sorghum‐Soybean Rotation and Fertilization Influence on Vesicular‐Arbuscular Mycorrhizal Fungi

Abstract

Vesicular-arbuscular mycorrhizal fungi (VAMF) can reduce plant stress resulting from nutrient deficiencies, drought, and other factors. The objective of this work was to measure the effect of soybean \Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] rotation and fertilization on plant response and VAMF root colonization and diversity, and relate effects to soil environment. Fertilizer treatments consisted of no fertilizer, N, and manure. Rooting densities correlated with previous crop, VAMF colonization, and soil NO,. Root colonization by VAMF was affected by previous crop, rooting density, N fertilization, soil P, and water-filled pore space. Root colonization by VAMF ranged from 93% at 15 cm to 15% at the 120-cm soil depth. Root density and VAMF colonization were least when soybean was grown the previous year and manure was applied. Root colonization by VAMF for control, N, and manure treatments were 54, 53, and 30%, respectively, for continuous soybean and 61, 55, and 44%, respectively, for soybean from rotation plots. Root colonization by VAMF for control, N, and manure treatments were 69, 59, and 54%, respectively, for continuous grain sorghum and 56, 48, and 31%, respectively, for grain sorghum from rotation plots. These agricultural soils contained a diverse mixture of 26 VAMF species, which is probably a major factor in the region's soil productivity. Plants stressed due to cropping system or fertilizer practice have greater VAMF colonization and VAMF activity. A diverse VAMF population could increase the ability of VAMF to respond to different stresses. C OLONIZATION OF PLANT ROOTS by VAMF often reduces adverse effects of plant stresses (water, nutrient, and environmental factors) and has beneficial effects in maintaining crop yields. Grain sorghum and soybean are colonized by VAMF. Rotating crops and application of N fertilizer may affect VAMF colonization and final crop yield. Clegg (1982) and Roder et al. (1989a) showed that rotating these crops improved crop yield, compared with continuous cropping. They were unable, however, to explain the rotation effect based solely on N availability. Since VAMF colonize the root system and serve as a link between plant roots and soil, changes in cropping systems that affect the soil environment should affect both roots and VAMF. The rate and patterns of root growth vary with soil water, soil strength, bulk density, soil aeration, soil temperature, chemical and biological soil properties,

The Influence of Bioproducts on Mycorrhizal Occurrence and Diversity in the Rhizosphere of Strawberry Plants under Controlled Conditions

“…On the other hand, consistent with this hypothesis, the treatment with Humus Active provided the lowest amount of nitrogen and phosphorous and induced the lowest root growth, while inducing very much inoculation and sporulation of AMF ( Table 2, Table 3 and Table 5). Nevertheless, even though there has been some reports about the factors impacting on spores numbers and colonization [73], the two group of species that produced on average the highest number of spores (i.e. C. claroideum and F. mosseae with or without R. fasciculatus) were not associated with a specific treatment, thus not possible to relate to their effect (Figure 1).…”

Effect of sorghum seedlings, and previous crop, on soil fluorescent Pseudomonas spp.

“…Field studies of sorghum in rotation cropping systems have indicated that planting of sorghum can modify numbers of pathogenic and beneficial fungi (Singh et al 1990;Ellis et al 1992;). It is recognized that cultural techniques are only able to assess a small portion of total microbial populations and simply changing the environment (e.g.…”

Mycorrhizal colonization and nutrient uptake of dry bean in manure and compost manure treated subsoil and untreated topsoil and subsoil

“…In contrast, mycorrhizae tend to develop most extensively under low fertility conditions (Brechelt, 1989). Ellis et al (1992) found that root colonization in sorghum and soybean was greatest when fertilizer was not added and lowest when manure was applied. Thus, manure application could potentially increase or decrease growth of mycorrhizae depending on which factors dominate.…”