Seed Physiological Quality Assessment
(35) Assessment of rubber tree seed physiological quality is determined by germination and tetrazolium tests. Germination is conducted in large plastic boxes filled with sterilized, sieved sand moistened to 70% water holding capacity at 25oC to 30oC. This species produces hypogeal seedlings and germination interpretations are performed at 15 and 30 days after sowing.
(36) To perform the tetrazolium test, seeds are conditioned between moistened paper towels for six hours at 30oC to attain at least 24% moisture content. The teguments are then removed, seeds cut longitudinally and placed in a 0.5% TZ solution at 40oC for 6 h. Following tissue color development, seeds are individually examined and separated into viable and non-viable categories based on the presence or absence of red-formazan color in vital areas.
The production of rubber tree seeds will continue to increase as an important activity in Brazil since the worldwide and local demand for natural latex industrialized products continues to increase. As shown, rubber crop yields have a close relationship with high quality grafted seedlings whose formation directly depends on optimized seed production and quality control programs as reported here.