Determination of Seed Storage Potential of Natural and Accelerated Aged Wheat (Triticum aestivum)
D. S. Chauhan & D. P. Deswal
Department of Seed Science and Technology, CCS, Haryana Agriculture University, Hisar- 125004
ABSTRACT: Seed of six varieties of wheat (Triticum aestivum) viz. C-306, PBW-502, WH-542, WH-711, WH-283 and RAJ-3765 were subjected to natural vis-à-vis accelerated ageing conditions and evaluated for relative storage potential of the seeds of respective varieties and ageing conditions. Seeds of all the varieties found 18 months of storability except the variety C-306 in term of minimum seed certification standards (MSCS) for germination percentage. Whereas variety RAJ-3765 was adjudged to have poor storability as it showed 18 months of seed storage potential under ambient conditions. After two years of storage all the wheat varieties loss their germination below minimum seed certification standards (MSCS). Maximum germination percentage retained by variety PBW-502(79.00), considered to have good storability as compared to others whereas minimum germination percentage retained by variety C-306(71.33) found to have poor storability. In case of accelerated aged seed lot maximum germination percentage retained by variety PBW-502(55.00) showed good storability whereas RAJ-3765(44.00) retained minimum germination percentage which showed poor storability among all varieties followed by C-306(47.00). Thus in both conditions natural and accelerated aged seed PBW-502 was adjudged good and RAJ-3765 was as poor storage genotypes. Secondly accelerated aged seed is having poor storability as compare to natural aged seed.
Key words: Accelerated ageing, natural ageing, wheat, seed quality, seed storability.
Various crop species have variable life span when stored under identical conditions. Two types of seeds viz. poor and good storers for seed storability have been identified. A third category having intermediate storability has also been included. However, these seed storability differences are not confined only to species, as many studies have demonstrated that storability variation prevails at the genotypic level too. Significant cultivar responses for differential seed storability have been reported in various vegetable crops (1, 2 and 3). There is not much information available as to the storage response and relative storability of cereal crops. Therefore, in view of the above, present study was undertaken to obtain reliable information on the seed storage potential and relative storability of six varieties of wheat by taking their natural and accelerated aged seed lots.
MATERIALS AND METHODS
The present research work was carried out in the laboratories of Department of Seed Science and Technology CCS Haryana Agricultural University, Hisar from 2006 to 2010. Seed material comprised of six varieties of wheat Viz. C-306, PBW-502, WH-542, WH-711, WH-283 and RAJ-3765 having germination above minimum seed certification standard (MSCS) was collected at the time of sowing of crop and stored in ambient conditions. For defining the variables for artificial ageing, seed of all six varieties were artificially aged (40±1ºC/72 hrs.) and observation was recorded after ageing. In case of natural ageing, observation was recorded quarterly on the stored wheat seed in cotton bags in ambient conditions up to one year till germination fall below as compared to fresh seed lot.
In case of natural ageing data on seed germination and seed vigour was recorded at quarterly intervals till germination fell below minimum seed certification standards which is 85 per cent for wheat. Standard germination test was conducted as per ISTA seed testing rules (4) and vigour index was calculated using formula given by Abdul-Baki and Anderson (5).
RESULTS AND DISCUSSION
Seed germinability of several species has been reported to reduce with age during storage (6, 7). In the present studies data on standard germination and seed vigour index after ambient storage (Table 1,2 ) as well as after accelerated ageing (Table 3,4 ) indicated that different wheat varieties registered differential seed storability. Seed of C-306 showed decline in per cent germination (76%) below minimum seed certification standards after 18 months of ambient storage conditions. However, PBW-502 maintained higher germination percentage (85%). In case of vigour index, maximum vigour index was retained by WH-542 (2460.40) and minimum by RAJ-3765 (2066.93). After two years of storage maximum germination percentage and vigour index was recorded in PBW-502 (79 per cent and 1072.03 respectively) and the minimum germination percentage and vigour was recorded RAJ-3765 (71.33 per cent and 891.65 respectively). One of the reasons associated with seed deterioration leading to them loss of germination and vigour is loss of membrane integrity. Accelerated ageing of various seed lots also showed the variability in storage potential of seed lots. After accelerated ageing maximum germination percentage and vigour index also retained by variety PBW-502 (55% and 742.50 respectively) and minimum germination percentage and vigour index retained by variety RAJ-3765 (44% and 524.92 respectively).
Table 1: Effect of natural ageing on seed germination (%) in Wheat
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With the increase in ageing period seeds undergo several structural, biochemical and genetic alterations. These include reduced capacity of synthesis of protein, lipids and RNA, injury to membranes, chromosomes and decreased repair systems (8, 9). Variable responses of genotypes to accelerated ageing conditions have also been reported in pea, cucumber, fenugreek (10, 11, 12). The reduction in seed vigour after accelerated ageing reported in cotton, turnip and sunflower (13, 14, 15). Similarly, decrease in germination percentage after natural ageing was recorded in different crops such as okra, cotton, carrot and onion (16, 17, 18, 19). From the present studies it can safely be inferred that RAJ-3765 is a poor storer after 18 months of seed storage potential under natural conditions whereas variety PBW-502 can be designated as good storer with 18 months of storage potential. The ageing is faster in artificial accelerated ageing mechanism may be due to constant deterioration conditions available in the ageing chamber while in the natural ageing there is up and down in temperature and humidity condition. Therefore there is more depletion in synthesis of protein lipid and injury to seed coat membrane as well as rapidly decreased the repair system.