2019 ASHS Annual Conference

Osmotic conditioning is commonly used to increase seed germination by growers seeking for heathier transplants. However, studies reported a large variation of seeds emergence among species, crop varieties, and even lots of same crop variety. The objective of this study was to compare the application timing and rate of different priming strategies on kale seeds emergence. Seeds of four kale varieties (Red Russian, Blue Ridge, Siberian, and Green Afro) were treated with water (for 3, 6, 9, and 12 h), polyethylene glycol (PEG6000) (at 0.2, 0.4, 0.6, and 0.8MPa for 4, 8, 12, and 15 h), and Progibb® LV (5,7% a.i.) (at 0.5, 1.0, 1.5, and 2.0 g a.i./L of solution for 15, 30, 45 and 60 min) to induce seeds emergence. Each priming treatment was considered a single experiment, and all experiments were randomized in a complete block design (r = 4). Treatments were applied at 70 °F and seeds were planted in a greenhouse with temperature varying between 65 and 90 °F. Emergence speed index (ESI) and total emergence (TE) were evaluated during 14 days, and number of leaves (NL), shoot height (SH), root length (RL) and dry matter (DM) after 21 days. Treatments were applied based on the imbibition curve, and kale seeds germinated after 17 h of imbibition. Variety effect was observed on most the response variables, in which Siberian, Blue Ridge, and Red Russian had the highest TE, ESI, and SH/RL respectively, regardless of priming. There was a significant interaction between variety and the Progibb® and PEG6000 rates on ESI and TE. A high ESI (3.89) was obtained on the Green Afro when PEG6000 was applied at a rate of 0.6MPa and Progibb® at a rate of 0.5 g a.i./L. Green Afro’s TE decreased by 10.5 and 9.4% when Progibb® rates increased from 0.5 to 1.5 and 2.0 g a.i./L, respectively. Similarly, maximum TE values of 90.9 and 89.4% were obtained with the application of PEG at 0.6MPa or when imbibition was carried out for 12 h, respectively. Overall, the products evaluated in this study had similar effect on total emergence and emergence speed index, however, crop variety should be considered on to improve seed vigor.