PHYSICAL AND PHYSIOLOGICAL QUALITY OF LEAD TREE AND CRATYLIA SEED

Abstract

The low availability of seed and technology for good shruby grassland establishment limits their adoption, so that, where programs exist, imported or backyard seeds are used, both with unknown quality; therefore, it is important to establish parameters that define physical and physiological quality, to discriminate between lots and plan the appropriate management for a successful planting. For this purpose, the physical quality (CalFis) and physiological quality (CalFisio) were evaluated in cratylia (Cratylia argentea) and lead tree (Leucaena leucocephala) seeds. For CalFis, the moisture content (CH), physical purity (PF), volumetric weight (PVol) and weight of 1000 seeds (P1000s) were determined. For CalFisio, germination tests (Ge) [to 7 (Ge7) and 14 days (dds; Ge14)] were carried out after sowing, cold test (PFr) and accelerated aging (EA), in addition to a test with germination stimulants; the first one under a completely randomized experimental design with factorial arrangement 2 × 3 (two species × three CalFisio tests), and the second under a completely randomized experimental design with factorial arrangement 2 × 4 [two species × three germination stimulants (EGe) consisting of hot water (HW: 80 °C for 3 min), KNO₃, AG₃ and control]. Response variables included Ge7, Ge14, abnormal seedlings (PA), hard seeds (SD), germination index (IGe), and germination speed index (IVGe7 and IVGe14). Data were tranformed to arcsin. Both species showed equal values for CH and PF (P ≥ 0.05). Lead tree showed higher PVol value in relation to cratylia (P ≤ 0.05); P1000s was 240 vs. 53 g for cratylia, and lead tree (P ≤ 0.05). In the first experiment, cratylia outperformed lead tree in all variables, except SD. In CalFisio, Ge was higher in Ge7, IGe and IVGe7, while PFr was higher in PA; EA increased Ge14 and IVGe14. In the second experiment, cratylia outperformed lead tree except for SD and IGe. For EGe, AC was higher in Ge7, SM, IGe and IVGe7. Treatment of AG₃ conditioning was superior in both Ge14 and IVGe14. Lead tree presented 85 % seed dormancy due to hard coat which prevents the passage of water and oxygen inside the seed. Recently harvested seed of cratylia showed no dormancy. Determining seed quality is a key factor for successful prairie establishment.