Arbuscular Mycorrhiza in Highly Fertilized Maize Cultures Alleviates Short-Term Drought Effects but Does Not Improve Fodder Yield and Quality

Abstract

Under fertilization levels specific to intensive farming, the impact of compensation of soil nutritional value by arbuscular mycorrhiza (AM) might be limited. Therefore, the question arises whether modern crop varieties, selected for high NPK assimilation rate, are able to gain symbiotic benefits under other challenging field conditions, such as drought. Accordingly, in this study we aimed to evaluate the contribution of Rhizophagus irregularis to the drought response of a stay-green corn hybrid in pot cultures equally fertilized until silking, compared to non-mycorrhizal (NM) counterparts. The highest tested fertilization regime not detrimental to the long-term vitality of intraradical hyphae reached the levels recommended for field cultivation of silage corn, except phosphorus application restricted to 60%. Under normal watering, mycorrhiza increased leaf nitrogen and phosphorus acquisition but only in cultures supplied with low NPK levels. At high fertilization levels, only the older leaves retained AM dependency, whereas for other leaf positions the AM-NM differences were leveled out. The similar size and nutritional status of highly fertilized AM and NM cultures, used in this study, eliminated fungal benefits before and during the 2-week drought progression. Nevertheless, mycorrhizal contribution became evident at the time of renewed watering, when AM plants showed much faster reversal of drought-induced leaf senescence symptoms: impaired photosynthesis and nitrogen management. Our results suggest that mycorrhiza can alter drought-induced senescence even in stay-green mutants. Moreover, this effect was apparently not mediated by AM-improved growth but triggered by activation of fungal transport at the time of recovery. Interestingly, the fungal protective potential was shown to be preserved at the expense of lowering AM vesicle number. It can be interpreted as engagement of hyphal nutritional resources targeted to maintain the symbiotic relationship despite the reduced vitality of the host. Finally, we compared the productivity of AM and NM cultures subjected to short-term drought at silking time and further fertilized with moderate or high NPK doses until the grain-filling stage. The yield and nutritive value of green forage showed that alleviation of drought-induced senescence by AM was not sufficient to have a significant positive effect on the final productivity compared to NM plants.

Improving plant growth and alleviating photosynthetic inhibition from salt stress using AMF in alfalfa seedlings

“…Under water deficit conditions, plants reduce transpiration rate by closing stomata to maintain the normal swelling pressure of cells. Therefore, the relative high G s in the +AMF treatment under salt stress may be related to the increased water absorption under salt stress by +AMF (Hodge et al 2009;Polcyn et al 2019). In addition to the limitation of stomatal factors, the photosynthetic capacity of plants is often reduced by non-stomatal factors under severe stress, such as decreased activity of the dark reaction-related enzymes.…”

“…Arbuscular mycorrhizal fungi (AMF) acquire energy by infecting the roots of host plants (Campos-Soriano and Segundo 2011 ), and rely on the host plants to complete their life cycle (Borde et al 2017). However, AMF also promotes the growth of host plants by promoting the uptake of nutrients (Karagiannidis et al 2002;Evelin et al 2009) and water (Hodge et al 2009;Polcyn et al 2019) by the host plants, which are mutually beneficial to the plant and fungi. Many experiments have reported that AMF can enhance plant stress resistance (Porcel et al 2012;.…”

Mutualistic Fungal Endophyte Colletotrichum tofieldiae Ct0861 Colonizes and Increases Growth and Yield of Maize and Tomato Plants

“…There are some other examples of beneficial fungi such as Glomus spp. and other arbuscular mycorrhizal fungi (AMF) [58][59][60][61][62][63] or the endophyte P. indica [64] that also have wide host ranges and show beneficial effects under different conditions. It has been shown that P. indica promotes vegetative growth and early flowering, improves seed germination, and increases yield in multiple plant species [13].…”

Composition variation of the essential oil from Ocimum basilicum L. cv. Genovese Gigante in response to Glomus intraradices and mild water stress at different stages of growth

“…A great many studies in the literature test the effect of arbuscular mycorrhizal fungi or water deficit in MAP, and a lesser amount examine the interaction of both according to Jayne and Quigley (2014). However, over the past five years, more papers have been published on the interaction of both factors on crops and MAP (Sun et al, 2017;Huang et al, 2017;Gheisari et al, 2017;Polcyn et al, 2019). A major goal of most studies examining water and mycorrhizal colonization is to improve the overall performance of plants with agricultural and horticultural importance, such as basil (Copetta et al, 2006;Hazzoumi et al, 2017).…”