Novel Effects of Leonardite-Based Applications on Sugar Beet
Maria Cristina Della Lucia, Giovanni Bertoldo, Chiara Broccanello, Laura Maretto, Samathmika Ravi, Francesco Marinello, Luigi Sartori, Giovanni Marsilio, Andrea Baglieri, Alessandro Romano, Mauro Colombo, Francesco Magro, Giovanni Campagna, Giuseppe Concheri, Andrea Squartini, Piergiorgio Stevanato
Abstract
The present study aimed to explore the effects of foliar application of a leonardite-based product on sugar beet ( Beta vulgaris L.) plants grown in the field. The approach concerned the evaluation of the community compositional structure of plant endophytic bacteria through a metabarcoding approach, the expression level of a gene panel related to hormonal metabolism and signaling, and the main sugar beet productivity traits. Results indicated that plants treated with leonardite (dosage of 2,000 ml ha –1 , dilution 1:125, 4 mg C l –1 ) compared with untreated ones had a significant increase ( p < 0.05) in (i) the abundance of Oxalicibacterium spp., recognized to be an endophyte bacterial genus with plant growth-promoting activity; (ii) the expression level of LAX2 gene, coding for auxin transport proteins; and (iii) sugar yield. This study represents a step forward to advance our understanding of the changes induced by leonardite-based biostimulant in sugar beet.