CO-IMMOBILIZED PLANT GROWTH-PROMOTING RHIZOBACTERIA IMPROVE RESOURCE UTILIZATION AND OFFSET GRAIN YIELD IN LATE-SOWN MAIZE PRODUCTION

FERNANDEZ MACARENA; MARTINEZ ROBERTO DIONISIO; PAGNUSSAT LA; MARCOS VALLE FJ; CREUS CECILIA

Congreso; SAMIGE 2023; 2023

Maize crop yield is on the rise mainly as a result of biotechnological advancements andchanges in crop management conditions, such as sowing date and plant density. The useof plant growth-promoting bacteria and the development of formulations that facilitate theiruse in the field and increase bacterial survival could accompany the increase in maize cropproductivity. This study aimed to contrast if co-immobilized bacteria in solid or liquidformulations have the potential to compensate for the decline in yield of the late-sown maizedue to the decrease in the availability of resources caused by high-density sowing. Wecarried out an experiment to model two scenarios of resource availability per plant. To dothis, the grain yield of maize crop (GY) and its components, grains per square meter (NG)and thousand-grain weight (TGW) were evaluated in trials sowing at two plant populationdensities: optimal and high both in per area (kg.ha-1) and per plant (kg.ha-1) basis. Thebacteria used in this study were Azospirillum argentinense strain Az39 and Pseudomonasrhodesiae strain ZME4. The inoculant dose corresponded to the application of 1 × 106CFU.g-1 of seeds for ZME4 and Az39 in liquid supports or immobilized in chitosan/starchbeads. The trials were carried out in randomized complete blocks with factorialarrangements. The factors were a) type of inoculum consisting of three levels, i.e., controlwithout inoculum, bead inoculum with Az39 + ZME4 immobilized and liquid inoculum withAz39r+ZME4; b) plant density consisting of two levels, i.e., optimal (70.000 pl. ha-1) and high density (120.000 pl.ha-1). Treatments inoculated with bacteria demonstrated improvedYG (kg.ha-1) when sowing the crop at optimum plant density, irrespective of the formulationused. When the crop was sown at high density, the higher plant competition, and lessresource availability, both produce a decrease in yield per plant. However, inoculanttreatment with bead-supported bacteria maintained crop yield when compared to theuntreated control and liquid formulations, in both per area and per plant basis. The factorresponsible for the increase in yield due to inoculation was NG. In contrast, TGW was onlydecreased by plant density, regardless of inoculation. In this context, we show that beadmediated inoculation improves inoculant application practices, having the potential toenhance resource acquisition or their utilization efficiency.