Influence of varieties on seed quality
Seed quality differs among the varieties in a crop. Among the varieties, significantly higher seed germination (99.10%) (Table 1), speed of germination (57.07) (Table 2), root length (22.09 cm) (Table 3), shoot length (16.33 cm) (Table 4), seedling dry weight (163 mg) (Table 5), seedling vigour index (3813) (Table 6) and lower electrical conductivity (0.299 dSm
-1) (Table 7) were recorded in variety V
1 (BG1105) as compared to variety MNK
-1 (98.15%, 38.44, 19.35 cm, 12.95 cm, 81 mg, 3173 and 0.520 dSm
-1, respectively). However, there was gradual decrease in seed quality with the advancement of storage period.
Similar trend was observed throughout the storage period, whereas at the end of fourteen months of storage V1 (BG1105) recorded significantly highest seed germination (91.40%), speed of germination (55.01), root length (16.96 cm), shoot length (10.87 cm) seedling dry weight (116 mg), seedling vigour index (2546) and lower electrical conductivity (1.068 dSm
-1) as compared to MNK
-1 (V2) (90.10%, 36.26, 14.60 cm, 7.57 cm, 59 mg, 2000 and 1.255 dSm
-1, respectively). This may be attributed to genotypic response of varieties, where V
1 (BG1105) was superior over MNK
-1 (V
2). Similar varietal response was reported by
Merwade (2000),
Gnyandev (2009) and
Sushma (2013) in chickpea.
Influence of modified gaseous on seed quality in Kabuli chickpea genotypes
The present study of modified atmospheric storage conditions exhibited significant effect on seed germination of chickpea seeds. The seeds which were stored with the gaseous combination of CO
2 (80%) + N
2 (20%) + O
2 (0%) (C
2) showed better germination throughout the storage period followed by the gaseous combination of vaccum packing (C
5) and CO
2 (75%) + N
2 (20%) + O
2 (5%) (C
3) and lowest was in control (C
1). The seed germination per cent due to concentrations of modified atmospheric gases varied significantly at all the month of storage period except for initial month. From second month of storage period significantly higher seed germination (99.88%) was recorded in C
2 (80% CO
2 + 20% N
2 + 0% O
2) treated seeds and it was followed by C
5 (vaccum treated seeds) (99.38%), while the lower (95.75%) was recorded in untreated seeds (control) (C
1). At the end of fourteen months of storage period the highest seed germination was recorded in C
2 (92.38%) and it was followed by C
5 (91.63%) and the lowest was recorded in control (C
1)(88.75%). Whereas, in the initial month numerically highest germination was recorded (99.88%) in C
2 and the lowest (96.63%) in control (C
1) (Table 1).
Modified atmosphere storage of seeds devoid of oxygen recorded higher seed viability for an appreciable period. Higher seed viability and vigour were maintained with modified atmospheric storage particularly in carbon dioxide and vacuum packaged condition. The probable reason for differences in longevity of seeds in the modified atmospheric storage conditions might be due to the variation in the gas concentrations, where the treatments C
2 and vaccum packing having gas combination of higher CO
2 with zero per cent of oxygen concentration
i.
e., low oxygen atmosphere and also the seeds stored under vacuum condition showed better germination as reported by
Meena et al., (2017). Whereas, germination was reported to decrease in peas with increase in oxygen level
(Roberts and Abdalla, 1968).
In general, ageing is manifested by decrease of metabolic activity and an increase of catabolic processes. In particular, an oxidative stress might be reduced in oxygen free storage atmospheres
(Justice and Bass, 1978; Benson, 1990). It should be noted that seed deterioration during storage could result in marked changes in the content and activity of enzymes capable for degrading the stored reserves
(Priestley, 1986; Wilson and McDonald, 1986; Walters, 1998). The advantage of higher seed reserve utilization efficiency in seeds stored in low oxygen concentration and vacuum packing, provide energy for a faster growing rate of the seedlings. In the present study also maximum speed of germination (48.83 and 46.40) was noticed in seeds stored in C
2 (80% CO
2+ 20% N
2 + 0% O
2) and C
5 (vaccum treated seeds) (Table 2), respectively compared to control (C1) (42.15) at the end of fourteen months of storage. The similar results were also reported by
Guillaumin (1928),
Rathi et al., (2000) and
Bera et al., (2008).
The root length and shoot length of Kabuli chickpea seeds were decreased gradually with the advancement in storage period. However, highest root length (17.99 cm) was recorded in C
2 (80% CO
2 + 20% N
2 + 0% O
2) treated seed followed by C
5 (vaccum treated seeds) (16.53 cm), while lowest was recorded in control (C
1) (13.64 cm) at the end of fourteen months of storage period (Table 3). At the end of fourteen months of storage period, highest shoot length (9.93 cm) was recorded in C
2 (80% CO
2 + 20% N
2 + 0% O
2) followed by C
5 (vaccum treated seeds) (9.32 cm), while lowest shoot length (8.72cm) was recorded in control (C
1) (Table 4). The decline in root and shoot length might be due to the damage caused by fungi and insects and also toxic metabolites which might have hindered the seedling growth. Similar findings were reported in onion
(Shivappa, 2011) and groundnut
(Shrishail, 2011). Deterioration in seed quality associated with decrease in root and shoot length with the passage of time had been confirmed by earlier workers in many crops.
In the present study, highest vigour index was recorded in C
2 (80% CO
2 + 20% N
2 + 0% O
2) treated seed (2581) followed by C
5 (vaccum treated seeds) (2367), while lowest was recorded in control (C
1) (1988) respectively (Table 6) at the end fourteen months of storage period. Gradual decline in seedling vigour index was noticed due to age induced decline in germination and decrease in seedling length.
The significant difference due to modified atmospheric storage conditions on seedling dry weight was recorded throughout the storage period. At the end of fourteen months of storage period, highest seedling dry weight was recorded in C
2 (80% CO
2 + 20% N
2 + 0% O
2) treated seed (99 mg) followed by C
5 (vaccum treated seeds) (88 mg), while lowest was recorded in control (C
1) (79 mg) (Table 5). This gradual decline in seedling dry weight may be due to deterioration of seed.
Whereas, at the end of fourteen months of storage period, lowest electrical conductivity (0.941 dSm
-1) of seed leachate was recorded in C
2 (80% CO
2 + 20% N
2 +0% O
2) treated seed followed by C
5 (vaccum packing) (1.096 dSm
-1). This might be due to the better maintenance of membrane integrity while, the highest electrical conductivity (1.427 dSm
-1) was recorded in control (C
1) (Table 7). Increase in electrical conductivity as the storage period advanced may be due to increased membrane permeability and decreased integrity of seed coat resulted in excess release of electrolytes which caused higher electrical conductivity. Such of these findings were also reported by
Shivappa (2011) in onion and
Shrishail (2011) in groundnut.