Reparation of aged lettuce (Lactuca sativa) seeds by osmotic priming andAzospirillum brasilenseinoculation

Abstract

Although Azospirillum spp. are considered to be important plant growth promoting bacteria, their possible effects on germination and vigor of aged lettuce seeds has not been previously evaluated. In fact, there is a paucity of published data about inoculation effects on seed germination. The aim of this work was to evaluate seed quality of one-year aged lettuce (Lactuca sativa L. cv. Crimor INTA) seeds after Azospirillum brasilense Sp245 inoculation with or without an osmopriming pretreatment. Fresh lettuce seeds were stored in the dark in a dry chamber for one year and then subjected to inoculation with A. brasilense Sp245, to osmotic priming with 0.37 mol/L MgSO4, or to both combined treatments. Seed germination, seed vigor, and seedlings emergence percentages were determined, and the abnormal seedling fraction was characterized. Azospirillum brasilense inoculation without a previous osmopriming enhanced seed vigor and seedling emergence percentages and decreased the fraction of abnormal seedlings. There was an additional effect of osmopriming as a previous treatment on germination percentage. We concluded that the use of A. brasilense inoculation alone or after an osmopriming treatment would contribute to overcome the negative effects of ageing on lettuce cv. Crimor INTA seeds.

Co-allocation Action of Azospirillum brasilense Inoculation and Seed Priming for Improving Germination and Seedling Growth in Aged Grass Seeds

“…However, the sole function of bacterial concentration was not significant. In this regard, Carrozzi et al noted that hydration treatment might affect only the early stages of imbibitions, while the function of A. brasilense is additive to the hydration process, which could result in repair actions for the promotion of aged seed germination [8] . It was also found that the germination of Russian wildrye 2009 during the early phases in all treatments lagged far behind that of the other seeds.…”

“…It was also found that the germination of Russian wildrye 2009 during the early phases in all treatments lagged far behind that of the other seeds. This phenomenon indicates that the germination percentage might have been intimately linked to the reparation of seed deterioration during the lag phase of germination [8] . Accordingly, for the older seed, a longer lag phase was required to reverse deterioration by seed priming.…”

“…Three factors were selected: the bacterial concentration of A. brasilense (factor A); the seed priming approaches viz., hydropriming (autoclaved distilled water), osmopriming (0.37 mol/L MgSO 4 ), and redox priming (H 2 O 2 -priming: 0.1% H 2 O 2 ) were selected based on numerous previous studies and pre-experiments (factor B) [4, 8] ; and priming time (factor C). Each factor was assigned three levels, and the nine treatment combinations of different parameters were laid out in an [L 9 (3 4 )] orthogonal matrix design replicated thrice (Table 1).…”

A newly discovered ageing-repair bacterium,Pseudomonas geniculata, isolated from rescuegrass (Bromus cartharticusVahl) promotes the germination and seedling growth of aged seeds

“…For the application of the PGPR inoculation, the surface-sterilized seeds were immersed in the bacterial suspensions or only phosphate-buffered saline for control seeds for 2 h at room temperature. The seed priming approaches viz., H 2 O-priming (autoclaved distilled water), osmopriming (0.37 mol/L MgSO 4 ), and H 2 O 2 -priming (0.1% H 2 O 2 ) was selected based on numerous previous studies and pre-experiments (Carrozzi et al 2012;Liu et al 2012).…”

“…Due to their highly beneficial effects on the growth and health of host plants, to date, PGPR have been actively applied worldwide as bio-inoculants to facilitate plant growth and alleviate various stresses, such as salinity, drought, and heavy-metal contamination (Li et al 2016). Various PGPR can promote plant growth through a wide variety of mechanisms, such as the production of phytohormones, the use of 1-Aminocyclopropane-1-carboxylate deaminase (ACCD) to lower ethylene levels, the enhancement of antioxidative activities, biological nitrogen fixation, or the up-or down-regulation of stress responsive genes (Carrozzi et al 2012;Liu et al 2012). Because most of the mechanisms of action could stimulate the germination of aged seeds, the possibility of repairing aged seeds through the action of PGPR has emerged as a valuable and feasible hypothesis.…”