Additive and synergistic effects of arbuscular mycorrhizal fungi, insect pollination and nutrient availability in a perennial fruit crop

Abstract

Managing ecosystem services may reduce the dependence of modern agriculture on external inputs and increase the sustainability of agricultural production. Insect pollinators and arbuscular mycorrhizal fungi (AMF) provide vital ecosystem services for crop production, but it remains unknown whether their effects on crop yield interact and how their effects are influenced by nutrient availability. Here we use potted raspberry (Rubus idaeus L.) plants in a full-factorial randomized block design to assess the interacting effects of insect pollination, AMF inoculation and four levels of fertilizer application. AMF inoculation increased the per-plant flower number by 33% and fruit number by 35%, independently from insect pollination and fertilizer application. Single berry weight furthermore increased more strongly with fertilizer application rates in AMF inoculated plants than in non-inoculated plants. As a consequence, AMF inoculation boosted raspberry yield by 43% compared to non-inoculated plants. Fruit yield of pollinated plants increased more strongly with fertilizer application rate than the yield of plants from which pollinators had been excluded. At maximum nutrient availability, the combined benefits of both ecosystem services resulted in a 135% higher yield than that of fertilizer-only treatments. Our results suggest that benefits of ecosystem services on yield can be additive or synergistic to the effects of conventional management practices. Intensive, high-input farming systems that do not consider the potential adverse effects of management on ecosystem service providing species may risk becoming limited by delivery of ecosystem services. Pro-actively managing ecosystem services, on the other hand, has the potential to increase crop yield at the same level of external inputs.

Nutrition vs association: plant defenses are altered by arbuscular mycorrhizal fungi association not by nutritional provisioning alone

“…The majority of land plants form symbiotic relationships with arbuscular mycorrhizal fungi [1][2][3][4]. These associations benefit plants in a myriad of biological and ecological gains [5][6][7][8]. The most often studied benefit is increased nutrient uptake in AMF colonized plants.…”

Potential tradeoffs between effects of arbuscular mycorrhizal fungi inoculation, soil organic matter content and fertilizer application in raspberry production

“…Potential tradeoffs between the effects of the two factors on raspberry yield would therefore not become apparent in these studies. This is further supported by the fact that Fig 3A is almost an exact copy of Fig 3 in [ 52 ]. Both these graphs show the effects of fertilizer and AMF on single berry weight under the same low SOM content levels.…”

“…Both these graphs show the effects of fertilizer and AMF on single berry weight under the same low SOM content levels. Furthermore, in our previous experiments we showed that part of the effects of AMF and SOM could be explained by their positive influence on flower visitation rate by pollinators [ 52 , 57 ]. Because pollinators were not considered in this study, this may have left unexplained any potential indirect effects of AMF inoculation and SOM content on flower visitation rate and consequently the final yield.…”

“…Additionally, we carefully counted the wilted or aborted flowers that failed to develop into fruits, which in combination with the fruit number allowed us to estimate the flower number. Because we could only have taken root samples at the end of the experiment, and earlier analyses showed AMF colonization rate of raspberry plants from different treatments did not differ after almost a year’s growth [ 52 ], we did not measure AMF root colonization rates.…”

Insect trash is a plant’s treasure: effects of insect exuviae as soil amendment on pollinator performance and plant reproduction

“…Pollination, the process of transferring pollen from an anther of a flower to the stigma of another flower has been one of the most studied plant-insect interactions (Faegri and Van Der Pijl, 2013). Insect pollination can enhance seed yield (Fijen et al, 2018;Chen et al, 2022) and sustain genetic diversity in natural plant populations (Kearns et al, 1998). Therefore, insect pollination is essential to maintain diversity and health of wild plants and the associated insect communities that depend on these plant populations (Lázaro et al, 2013).…”