Assessment of different pretreatments to breakage dormancy and improve the seed germination in Elaeocarpus serratus L. - an underutilized multipurpose fruit tree from South India

Abstract

The seeds of Elaeocarpus serratus, a tropical underutilized fruit tree are characterized by hard seed coat and consequent poor water uptake and low germination. To improve the regeneration through seeds, various parameters such as viability of seeds, water uptake, and effect of seed mass on germination and pretreatments were performed using a completely randomized design (CRD). Tetrazolium (TZ) test was conducted using fresh, mature seeds revealed 50 ± 2.56% mean viability. Seeds of different weight classes showed similar pattern of water uptake and the saturation level was achieved at 60 hrs of soaking. Seeds belong to weight class 2.6-3.5g were germinated (12.5 ± 1.26%) with 175 ± 1.75 days (d) of mean time taken for germination (MTG). Germination capacity of seeds varied significantly among different populations and Varkala population gave 12.5 ± 1.1% germination with 174.6 ± 2.5 d MTG. Among various seed treatments, mechanical scarification was superior in germination and significant reduction in MTG (p ≤ 0.05). The mechanical scarification by complete removal of seed coat resulted in 49.2 ± 1.52% germination within a short period of time (9.52 ± 0.89 d MTG). However, the complete removal of seed coat without damaging to embryo is a difficult task. An alternate treatment (Mechanical scarification II) by making cracks on nut faces vertically followed by soaking in distilled water for 24 hrs gave 48.4 ± 1.73% germination with significantly reduced MTG (12.14 ± 0.56 d) over unsoaked, untreated control (6.5 ± 1.84% germination and 197.18 ± 1.79 d MTG; p ≤ 0.05). This treatment (Mechanical scarification II) is therefore recommended for E. serratus seeds as it can adopt easily and can achieve 7 fold increases in germination over control. The recorded germination through mechanical scarification is in tune with realized viability percentage of the seeds.