Seed priming improves the germination rate as well as uniformity. An enhanced and uniform seedling emergence may contribute to regulate crop establishment. Analysis of variance revealed substantial differences between seed priming duration and copper levels on all of the germination parameters examined in the laboratory studies.
Scrutiny of the data with regards to germination per cent of coriander seeds primed with different levels of copper for 14 h, 16 h and 18 h (Table 1) revealed a significant variation in the germination per cent of coriander under laboratory condition. The data manifested that the highest germination per cent (82%) was achieved by T
11 (seeds primed with Cu 500 ppm for 16 h) which was at par with T
12 (seed primed with Cu 500 ppm for 18 h) with 80% and T
10 (seed primed with Cu 500 ppm for 14 h) with 76%. The germination percentage for T
1 (seed primed with Cu 0 ppm for 14 h) was the lowest (64%). The germination of primed seeds was more rapid and uniform than that of unprimed ones. Similar results were reported by
Rouhi et al., (2018) in their study on hydro priming with distilled water for 15 h improves the germination of coriander with higher antioxidant enzyme activities, soluble sugars and total proteins of primed seeds than of non-primed. Soaking cucumber seeds for 24 h improves the germination attributes
(Shakuntala et al., 2020) while 48 h of seed hydro-priming was found to be effective for increasing germination and seedling growth in bitter gourd
(Adhikari et al., 2021). In the study by
Sabongari and Aliero (2004) observed that the seeds of tomato variety Roma VF, UC82B and Xina showed maximum germination % under 24 h treatment. The study of
Elkoca et al., (2014) reported that seed priming duration of 24 h had a negative effect on the germination of pea cv. Winner compared to 12h priming. Similar reduction in germination parameters by increasing priming duration was observed in soybean
(Khalil et al., 2001). Murray (1989) concluded that over priming may cause oxygen deficiency and the build-up of inhibitors resulting reductions in germination parameters. The higher dosages are hazardous, which has a negative impact on seed germination and plant growth
(Adhikari et al., 2012). In the present study on coriander variety Jawahar Dhaniya-1, it was observed that germination percent of coriander was improved by 82% when treated with Cu @ 500ppm. This was in correspondence with the work reported by
Mehra et al., (2022) on same variety of coriander Jawahar Dhaniya-1. They adumbrated that seed primed with Mn 450ppm recorded maximum germination (96.81%) followed by Cu at 450 ppm with 95.81%.
The mean germination time is a measure of the time taken for the seed to germinate, focusing on the day at which most seeds have been germinated. The stimulation of metabolic activity in the embryo was probably responsible for the increase in germination percentage and rate as well as the decrease in germination time. Priming synchronizes all the cells of the germinating embryo in the G2 Phase of the cell cycle so that upon further imbibitions, cell division proceeds uniformly in all the cells ensuring uniform development of all parts of the seedlings
(Varier et al., 2010). Information on the mean germination time of different priming treatments is shown in Table 1. The results revealed significant variations among the treatments it decreased significantly with the increase in the soaking duration. In the present investigation the least mean germination time (7.9 days) was taken by T
11 (seeds primed with Cu at 500 ppm for 16 h), which was at par with
T12 (seed primed with Cu @500 ppm for 18h) with 8.0 days Mean Germination Time and T
10 (seed primed with Cu 500 ppm for 14 h with (8.9 days) Mean Germination Time. Maximum (11.2 days) were spent in T
1 (seed primed with Cu 0 ppm for 14 h) in the same way
Mehra et al., (2022) also reported least mean germination time of 6.99 days when treated with Mn @450 ppm followed by Cu @ 450 ppm with 7.51 days. The study on Arka Anamika variety of okra
Lamichhane et al., (2021) reported maximum germination (60.12%), seed vigour (5772.68 cm) and mean germination rate (7.53 seeds per day) in seed priming with GA3 @ 200 ppm for 24 h. According to
Basra et al., (2006), during water absorption, DNA replication, RNA activity stimulation, protein synthesisand germination-stimulating hormones like auxin and ethylene increased resulting increased germination in comparison to the control group. Earlier germination of primed seeds may be due to increase in activity of enzymes such as amylase, protease and lipase which have great role in breakdown of macromolecules for growth and development of embyo as revealed by
Dell-Aquila and Tritto (1990).
The germination index data revealed in Table 1 showed significant differences between the treatments. Scrutiny of the data revealed a steady increase in Germination index with the increase in concentration of Cu as well as duration of soaking. The treatment T
11 (seed primed with Cu @ 500 ppm for 16 h) recorded the highest germination index of 22.83, followed by T
12 (seed primed with Cu @ 500 ppm for 18h) with 17.73 GI and T
10 (seed primed with Cu @ 500 ppm for 14 h) with 17.31 GI. T
1 (Seed primed with Cu 0 ppm for 14 h) recorded to have the lowest (9.82) germination index values.
The data on length of radicle and plumule is given in Table 1. The outcome showed that the length of the radicle and plumule was significantly increased by the varied priming concentration of Cu. The T
11 (seeds primed with Cu @ 500 ppm for 16 h) produced the longest plumule, measuring 13.09 cm and produced radicle with a maximum length of 17.30cm which was at par with the treatments T
12 (seed priming with Cu @ 500 ppm for 18 h) and T10 (seed primed with Cu @ 500 ppm for 14 h), which produced plumule of length 13.06 cm and 12.70 cm, respectively and radicle length of 14.90 cm and 14.74 cm, respectively . In T
1 (seed priming with Cu @ 0 ppm for 14 h), the radicle and plumule length was shortest 12.42 cm and 11.86 cm respectively. Similar result were reported by
Sarkar et al., 2020 with the highest root (21.4 cm) and shoot length (12.3 cm) was found when seeds were primed with 2% KH
2PO
4 for 20h in coriander.
Akram et al., (2020) demonstrated that seed priming with 40 µM copper sulphate produces maximum shoot (15.21cm) and root length (11cm) of green gram while higher concentration of CuSO
4 (80µM) decreases the shoot and root length (3.27 cm) due to copper stress which decreased the process of cell division.
Abdoli (2014) primed fennel seeds with PEG solutions and found an increase in the length of plumule, radicle and seedling, similarly increase in fresh and dry mass production of seedlings. Similar results were also reported by
Mahdavi and Rahimi (2013) in their study under salt stress condition the ajowan seeds when primed with chitosan solution improved the germination and growth parameters like germination %, germination rate, seedling vigour index, hypocotyl length, radicle length and dry radicle weight. Chitosan is a polysaccharide biopolymer which stimulates growth of plants and also increases the crop yield. In priming, the osmotic pressure and the duration of maintaining the seeds in contact with the membrane are enough to allow pre-germinative metabolic processes to be occurring within the seeds up to a level limited to that instantly preceding radicle emergence
(Gour et al., 2019). Accumulation of more sugar which could readily support metabolic activity leading to faster seedling emergence (
Sung and Chang, 1993). Increase in beta-tublin in the radicle tip has been observed during the seed priming by
Bino et al., (1992). Microtubules (MTs) are elongated tubular structures, made of α and β-tubulin, which in plant cells play an important part in cell elongation, determination of the division site, chromosome separationand cytokinesis (
Alberts et al., 2002 and
Wasteneys and Galway, 2003).
The ability of a seed to establish seedlings quickly and uniformly is determined by an array of biochemical and molecular processes, which together make up the complex feature known as seed vigour. The data for the Vigour Index-I and Vigour Index-II was conferred in Table 1. The results showed that particular concentration of Cu had a favourable impact on the vigour index-I. Treatment T
11 (Seed priming with Cu @ 500 ppm for 16 h) was found to demonstrate the maximum vigour index-I value, measuring 2,374.05 cm and highest vigour index-II of 12.29 g value followed by T
12 (seed primed with Cu @ 500 ppm for 18 h) and T
10 (seed primed with Cu @ 500 ppm for 14 h), each of which had vigour index-I values of 2,122.12 and 1,938.33 cm respectively and vigour index-II of values 10.45 g and 10.12 g respectively. T
1 (seed primed with Cu 0 ppm for 14 h) had the lowest vigour index-I and vigour index-II score 1,606.89 cm and 6.06 g respectively. This corresponds to the results reported by
Sarkar et al., (2020), that highest seedling vigour index (3000 cm) was the result of seed primed with 2% KH
2PO
4 for 20h in coriander. In the study of
Mehra et al., (2022) reported that the highest vigour index-I (1172.72 cm) and vigour index-II (5.36 g) was noticed from seed priming with Mn @450 ppm followed by Cu @450 ppm compared to control (unprimed seeds). Further more,
Mahmoodi et al., (2011) in their research concluded that priming for 18h improves seedling vigour and field establishment of maize. Seed priming leads to enhancement in the vigour due to increase in the seed hydration status required to achieve critical and threshold water potential for germination finally leading to rapid and uniform field crop establishment and increased seed yield
(Koutu et al., 2019). The valuable effects of seed priming on seed germination rate are associated with the repair and build-up of nucleic acid, enhanced synthesis of RNA and proteins, repair of membranes and some age-induced damage
(Bray et al., 1989) and enhanced respiratory activity of seeds
(Benamar et al., 2003).
The study revealed a substantial effect between copper levels and soaking times. From the result it can be concluded that seed priming with Cu @ 500 ppm soaking for 16 h improves the germination and vigour characteristics of the seedlings which is closely followed by Cu @ 500 ppm soaking for 18h.