Tripartite Relationships in Legume Crops Are Plant-Microorganism-Specific and Strongly Influenced by Salinity

Eriola Veselaj,Glenda Sallaku,Astrit Balliu

doi:10.3390/agriculture8080117

Abstract

This study investigated the effects of specific strains of two arbuscular mycorrhizae fungi (AMF) (Rhizophagus irregularis and Claroideoglomus claroideum) and of two plant growth-promoting bacteria (PGPB) (Rhizobium leguminosarum and Burkholderia spp.), supplied either individually or as combination of a mixture of both arbuscular mycorrhizae fungi with each bacteria on root morphology, growth and fresh grain yield in pea (Pisum sativum L.) plants. Inoculated and non-inoculated pea plants were subjected to two levels of salinity (0 and 50 mM) by the addition of sodium chloride into tap water. Prior to fresh grain harvesting the morphology of root system was analyzed and the dry matter of roots and shoots were individually measured in randomly selected plants. Fresh pods were individually harvested per each plant; fresh (green) grains were separately counted and weighted per each pod at each individual plant, and the average grain weight was calculated by dividing total grain weight of plant with the respective number of green grains. The raise of salinity in the irrigation water strongly diminished the growth of pea plants by significantly reducing weight, length, surface area and root volume of pea plants. The relationships of pea plants with beneficiary fungi and bacteria were specific to each microorganism and highly depended on the environment. We found that under saline conditions, Rhizophagus irregularis provided a better vegetative growth and a higher yield than Claroideoglomus claroideum. Although, single application of Burkolderia spp. provides a better vegetative growth than single application of Rhizobium leguminosarum the best results, in terms of growth and harvested yield, were still obtained by combined application of AM fungi with Rhizobium leguminosarum. This combination was able to sustain the average grain weight at the level of non-saline plants and provided a significantly higher yield than the control plants.

Highlights

With the increase in the world’s population, the demand for agriculture yield has increased tremendously, thereby leading to large-scale production of chemical fertilizers [1]
+ Claroideoglomus with each bacteria have (Rhizophagus irregularis + Claroideoglomus claroideum) with each bacteria have contributed to significantly higher values of each of analysed root parameters (RL, RSA, RV) compared to control significantly higher values of each of analysed root parameters (RL, RSA, RV) compared to control plants (Table 1)
The longest root length was obtained in Burkholderia sp.-inoculated (Brh)+ and Rh.l+ plants (respectively 1200 plants (Table 1)

Summary

Introduction

With the increase in the world’s population, the demand for agriculture yield has increased tremendously, thereby leading to large-scale production of chemical fertilizers [1]. Since one of the most important factors in the generation of high yields from crop plants is nitrogen, farmers are applying high amounts of the fertilizers which are very costly and make the environment hazardous. Progressively reduced N use efficiency due to increased fertilization doses has been reported since the early stages of plant growth [3]. Increasing global concern regarding the production of enough food to uphold the growing human population has been reinforcing the importance of sustainable intensification of plant production [4], and the use of microbial consortia of plant-growth promoting bacteria (PGPB) is the current trend in agriculture [5]. It is already recognized that microbial communities are much more diverse than previously thought [6], and there are vast opportunities of using them

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