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.

Comparative study of various pretreatment on seed germination of Dalbergia cochinchinensis

“…Scarification treatment reduced MGT, but not improved the germination of D. cochinchinennsis. Similarly, Raji and Siril (2018) reported that the mechanical scarification was superior in reduction of MTG. Amoakoh et al (2017) found that mechanical scarification improves germination of P. campachiana while soaking with cold water has a negative influence on seed germination.…”

“…In case of D. cochinchinensis the GA 3 treatment was not effective to increase germination. Confounding to this by Raji and Siril (2018) the case of E. serratus the GA 3 treatment was ineffective to improve germination or reduce MTG.…”

Dormência e germinação de sementes de Uvaia (Eugenia pyriformis Cambess)

“…Several dormancy overcoming mechanisms may be employed; however, the most suitable ones are linked to the dormancy kind present in the seed [10]. When there is tegumentary dormancy, caused by an impermeable seed tegument, methods aiming to soften and render the tegument more water-permeable are needed, such as water imbibition or mechanical/chemical scarification.…”

“…For embryos that have germination inhibitors present in the cotyledons or that need to be exposed to heat to release germination factors, thermal shock using hot water may be employed. The induction of germination by imbibition in gibberellin solutions may also be carried out to enhance seed germination and vigor [6,[10][11].…”

Tree Regeneration by Seeds in Natural Forests

“…Conversely, each tree may also have exceptionally good years of seed production. Presowing treatment usually means dormancy breaking (e.g., hard seed coats [4]) or various surface treatments of seeds (e.g., antifungal spray or coating [5]), which can both take place in different ways. Then, the seeds may be sown directly in the prepared soil in the forest, or they may be sown in forest nurseries, which are plots with equipment used for the production of planting material.…”