Abstract
Most of the wild and native legume seeds has a hard and impermeable testa, which causes physical dormancy and prevents them from germinating even when environmental conditions are favorable. The study evaluated the effect of scarification treatments on germination and enzymatic activity of Crotalaria longirostrata (Cl) and Lupinus exaltatus (Le) seeds. After scarification treatments, germination percentage (GP) and rate (GR) were assessed during 30 days after seeding (DAS); and water absorption (WA) and specific enzymatic activity (SEA) during early germination (0, 6, 18, 36, 72, 120 h) in a growing chamber at 25 °C and photoperiod of 12 h. Scarification with 98% H2SO4 15 min increased GP and GR in both species. At 30 DAS, GP and GR of Le seeds were 34% and 0.97 seeds day-1, respectively. In Cl seeds, GP was 64% and GR 0.90 seeds day-1. Scarification with H2O at 80 °C 1 min also promoted germination in Cl (52%). At 120 h after seeding, Le and Cl seeds showed already a high GP with acid scarification (31% and 48%, respectively). In seeds of both species, scarification treatments affected WA and SEA during early germination. During this period, scarification treatments that increased GP also showed a higher α-D-galactosidase activity. The maximum enzyme activity was observed 72 h after hot water scarification in Cl (82.6 U/mg total protein), followed by acid scarification (54.5 U/mg total protein). In Le, the activity peak was 36 h after acid scarification (9.5 U/mg total protein). No relationship was observed between β-glucosidase activity and GP in both species. In conclusion, during early germination of both species, the increase in GP is accompanied by a rise in α-D-galactosidase activity between 36 and 72 h after seeding; and in Cl seeds, an alternative scarification treatment to increase GP may be the use of hot water.
Highlights
Legumes are essential components of ecosystems and crop systems because of the biological capacity to fix atmospheric nitrogen
Dry fruits of L. exaltatus L. were collected in August 2014, and those of Crotalaria longirostrata Hook. & Arn. fruits in September 2013, from plants grown in agroecosystems of the states of Puebla and Tabasco, Mexico, respectively
Germination rate decreased with germination time, the highest was five days after seeding (DAS) after acid pre-treatment (4.8 seeds day-1 in C. longirostrata and 3.8 in L. exaltatus)
Summary
Legumes are essential components of ecosystems and crop systems because of the biological capacity to fix atmospheric nitrogen. They have a vital role in food security and in resilience from effects of climate change (Liew et al, 2014). Application of acid or heat treatments can release physical dormancy in legumes seeds; and effectivity of these scarification treatments to promote germination range from 12 to 100% in Lupinus and Crotalaria species (Elliott et al, 2011; Alderete-Chávez et al, 2010a, b; Ayala‐Herrada et al, 2010; Tiryaki and Topu, 2014)
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More From: Brazilian journal of biology = Revista brasleira de biologia
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