Soybean [Glycine max (L.) Merrill.] seed quality under different production environments, storage conditions and seed invigoration using humic acid
The government of Sri Lanka has targeted to increase the production of soybean by the area cultivated. This target was unable to be achieved due to lack of supply in good quality seeds at time of planting. Currently, seed production is only carried out in a single location in Sri Lanka, hence new...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2022
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104435/1/WEERASEKARA%20MUDIYANSLAGE%20%20-%20IR.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The government of Sri Lanka has targeted to increase the production of soybean by the
area cultivated. This target was unable to be achieved due to lack of supply in good
quality seeds at time of planting. Currently, seed production is only carried out in a single
location in Sri Lanka, hence new areas for seed production are required. Seed quality is
influenced by both the pre-and post-harvest factors. However, effect of pre harvest
production environments on seed quality has not yet been clarified. Therefore, the aim
of the first study was to determine the effect of seed production environment on seed
development, maturation, and subsequent seed quality. The experiment was conducted
at six production environments, three locations [Alutarama (ALU), Polonnaruwa (POL)
Mahailuppalama (MI)] over two planting cycles (P1, P2). Seed development and
maturation, seed and seedling quality characteristics were evaluated at five reproductive
(R6, R7, R8, R8+5 and R8+10) maturity stages. The study infers that production
environment at the late reproductive (LR) stage (R6-R8) was critical in determining the
seed quality. If the LR coincides with more than 100 mm of rainfall or 75% of relative
humidity considered as wet environment, otherwise considered as dry. A longer duration
was required for the seeds to mature, around 27.5 days, if the LR stage coincided with
wet environment (P1 ALU, P2 ALU P2 POL), in contrast to only 17.5 days in dry
environment (P1 MI, P1 POL, P2 MI). Seed lots from dry environment during LR stage
surpassed the minimum quality standards (75% final germination) at maturity stage R7
onwards, while this only occurred at maturity stage R8 for wet environments. Soybean
seeds with minimum quality standards can be produced in all three locations provided
harvesting is done at the correct LR stage. However, the quality of the seeds upon storage
may differ due to the influence of the production environment. In the second experiment,
full mature stage (R8) seeds were obtained from six environments, and upon drying,
seeds were stored over one-year period in two different conditions, ambient (24.6 - 33.8
°C, RH 37-88%) and modified storage condition (20 °C ± 2°C, RH 60-70%). The quality
of the stored seeds was evaluated at different storage periods (0, 2, 4, 6, 8, 10, 12 months)
to monitor the rate of deterioration. Seeds were subjected to germination and vigor test,
antioxidant enzyme activities, and malondialdehyde content. Seed lots that matured in
dry environments maintained minimum quality standards for over 12 months under
modified storage conditions while only 8 months of storage was possible in ambient
condition. A slower rate of reduction was obtained in antioxidant capacity for seeds
stored under modified conditions compared with ambient. Thus, modified store is
recommended with comparatively low construction (1/3) and running (1/4) cost
compared with cold storage. Despite the improvement in storability, decline in seed
vigour during storage is inevitable due to ageing. The ageing effects can be alleviated,
through seed priming. Thus, the third experiment investigated the effects of Humic acid
(HA) (an environmentally safe priming agent) on activities of antioxidant enzymes and
lipid peroxidation along with the consequences on seed germination in naturally aged
soybean seed. Seed lot that was removed from a 12-month storage under ambient
condition with 60±5% germination was primed using distilled water or 0.2 g/L HA
solution at 25 °C for 1, 3, 5 and 7 h with non-primed dry seeds as control, resulting in
nine treatment combinations. Laboratory and field experiments were carried out to test
for the best priming treatment to improve seed germination and seedling vigour. HA
priming for 5h mitigated the adverse effect of seed deterioration on germination-related
traits by increasing the antioxidant enzyme activity [catalase (CAT) and peroxidase
(POD)] and reducing malondialdehyde (MDA) content. In conclusion, soybean seeds
can be produced above the minimum quality standard in P1 at MI and POL by managing
planting time (from January to March and in P2 at ALU, POL and MI from June to
August and can be stored for 8 months under modified storage condition. Overall
findings from this study can be used to increase soybean seed availability at time of
planting. |
|---|