Comparison of pre-germination treatments in <em>Lupinus</em> spp. and their effects on germination and related solutes

Abstract

Background. Physical dormancy in seeds of the genus Lupinus restricts their ecological or agricultural use. Hypothesis. This dormancy can be broken when seeds are subjected to physical and chemical pretreatments that increase germination, mobilize reserves and decrease ABA. Studied species. Seeds of Lupinus exaltatus (Le), L. campestris (Lc) and L. montanus (Lm) from Puebla, México. Methods. The following seven treatments, including a control, were applied: PG1 = 98 % H2SO4 for 15 min, PG2 = wet sand at 80 °C for 5 min, PG3 = wet sand at 35 °C for 8 h and 16 h at 25 °C, PG4 = dry sand at 80 °C for 7 min, PG5 = dry sand at 150 °C for 1 min, PG6 = H20 at 80 °C for 1 min, Control = untreated seeds. On days 0, 3, 5, 10 and 15 after seeding, we evaluated the percentage and rate of germination (GP and GR, respectively) and biochemical changes. Results. PG6 produced a higher GP in Le (41 %) and Lc (69 %), and PG1 produced a higher GP in Lm (37 %). In all three species, the highest GR was obtained with PG1 (1.95, 2.27 and 2.22 day-1 seeds, respectively). PG6 increased the protein concentration (53, 17, and 43 % for Le, Lc and Lm, respectively), amino acids (19, 44 and 31 %, respectively), reducing sugars (63, 18 and 96 %, respectively) and polyphenols (32, 55 and 75 %, respectively) but decreased soluble sugars (22, 29 and 23 %, respectively) and ABA relative to the control. Although only the correlation between the GP and amino acid content was significant and positive, and the correlation between GP, GR and soluble sugars was significant and negative. Conclusions. The effect of pre-germination treatments on germination was species-specific. The pretreatment with H20 at 80 °C for 1 min increased germination and mobilized the seed’s reserves in the process.

Keywords

• Lupinus
• physical dormancy
• germination
• protein
• sugars