Study the Fresh Seed Dormancy in Sesame (Sesamum indicum L.)

The sesame seed of five varieties viz., GT 2, GT 3, TKG 22, Pragati and GT 10 were produced in kharif season and of three varieties viz., GT 2, GT 3 and GT 5 were produced in summer season at two locations of the Junagadh Agricultural University, Junagadh namely Agricultural Research Station, JAU, Amreli and Sagdiwidi Farm, JAU, Junagadh. The seed of five varieties produced at both the locations were brought immediately to the Department of Seed Science and Technology, College of Agriculture, JAU, Junaagdh and the observations were recorded on germination percentage immediately followed by 10 days interval along with the old seeds supplied by Agricultural Research Station, JAU, Amreli, of all these five varieties. From the results, it was concluded that freshly harvested seeds of white seeded sesame varieties GT-2, GT3, TKG 22, Pragati and GT-5 produced in the previous season could not be utilized for sowing, as seed dormancy was found in these varieties and it was released after 115, 115, 95, 105 and 105 days after harvesting, respectively. However, black seeded variety GT 10 could be utilized for sowing in the next season, as it released the dormancy after at 35 days after harvesting (DAH).


INTRODUCTION
In sesame, germination problem observed when summer produce is utilized for kharif sowing; one of the reasons would be the existence of dormancy. Some reports are available on seed dormancy in sesame as reported by Ashri and Palevitch (1979) in Mexican cultivar Cola de Burrego and Tanesaka et al. (2012) in S. mulayanum and F 1 hybrid of S. mulayanum and S. indicum. No such studies of Indian sesame varieties in general and Gujarat varieties in particular have been carried out. Therefore, whether dormancy is present in Gujarat sesame varieties or not, a preliminary study was carried out by Department of Genetics and Plant Breeding, JAU, Junagadh. The study was carried out up to 30 days after harvesting and the results showed that dormancy in sesame seed is there.

RESULT AND DISCUSSION
The seed of five varieties viz., GT 2, GT 3, TKG 22, Pragati and GT 10 were produced at both the locations (Agricultural Research Station, JAU, Amreli and Sagdiwidi Farm, JAU, Junagadh) during kharif 2016, 2017 and 2018. However, the seed production at Sagdividi Farm, JAU, Junagadh was failed due to high rainfall at harvesting stage in kharif 2016, while the seeds of three varieties viz., GT 2, GT 3, and GT 5 were produced during summer 2017, 2018 and 2019 at both the above locations.
The results of Amreli location of kharif 2016 revealed the presence of seed dormancy in sesame (Table 1). The old seeds are germinated, but amongst the fresh seeds of the five varieties, GT 10 was reached to the optimum germination (above 80 %) after 25 DAH; TKG 22 and Pragati were reached to optimum germination after 105 DAH; while in remaining two variety. GT 2 was reached to optimum germination at 115 DAH and GT 3 was reached to optimum germination at 125 DAH.
The results of seed produced during kharif 2017 at both the locations (Table 1) revealed the presence of seed dormancy in sesame. The old seeds are germinated as per the seed standards right from first date of observation, while the fresh seeds showed seed dormancy. Of the five varieties, GT 10 was reached to the optimum germination (above 80 %) after 25 DAH in Amreli location and 35 DAH at Junagadh location. Variety TKG 22 was reached to optimum germination after 75 DAH and 105 DAH at Amreli and Junagadh, respectively. Pragati was reached to optimum germination at 115 DAH at Amreli location and 125 DAH at Junagadh location. GT 2 reached to optimum germination at 105 DAH at Amreli location and 125 DAH at Junagadh location, while GT 3 reached to optimum germination at 85 DAH at Amreli location and 125 DAH at Junagadh location.
The results of seed produced during kharif 2018 at both the locations (Table 1) revealed the presence of seed dormancy in sesame. Of the five varieties, GT 10 reached to the optimum germination (above 80 %) after 55 DAH in Amreli and 45 DAH at Junagadh location. TKG 22 reached to optimum germination after 85 DAH and 95 DAHat Amreli and Junagadh, respectively. Pragati reached to optimum germination at 95 DAH at both the locations. GT 3 reached to optimum germination at 105 DAH at both the locations, while GT 2 was reached to optimum germination at 115 DAH at both the locations.
The results of seed produced during summer 2017 at both the locations (Table 1) revealed the presence of seed dormancy in sesame. The old seeds are germinated as per the seed standards right from first date of observation, while the fresh seeds showed seed dormancy. Of the three varieties, GT 5 was reached to the optimum germination (above 80 %) after 65 days of harvest at Amreli, while it reached to the optimum germination (above 80 %) after 125 days of harvest at Junagadh. Varieties GT 2 and GT 3 reached to the germination above 80 percent after 145 days of harvest at both the locations.
The results of seed produced during summer 2018 at both the locations (Table 1) revealed the presence of seed dormancy in sesame. Of the three varieties, GT 5 was reached to the optimum germination (above 80 %) after 75 DAH at Amreli location and 95 DAH at Junagadh location, while GT 3 reached to the germination above 80 per cent after 125 DAH at both the location, whereas GT 2 reached to the optimum germination after 125 DAH at Amreli location and 115 DAH at Junagadh location.
The results of seed produced during summer 2019 at both the locations (Table 1) revealed the presence of seed dormancy in sesame. Of the three varieties, GT 5 was reached to the optimum germination (above 80 %) after 85 DAH at Amreli and 95 DAH at Junagadh location, while GT 2 and GT 3 both reached to the germination above 80 percent after 115 DAH at Amreli and 105 DAH at Junagadh location.
From the above results, it can be concluded that seed dormancy is present in sesame. Among the different varieties tested, on an average, black seeded variety GT 10 released the dormancy (as per the IMSCS, > 80 %) at 35-40 DAH, while all the white seeded varieties tested released the dormancy after 100-115 DAH.

CONCLUSION
The experiment concluded that freshly harvested seeds of white seeded sesame varieties GT-2, GT-3, TKG 22, Pragati and GT-5 produced in the previous season could not be utilized for sowing, as seed dormancy was found in these varieties and it was released after 115, 115, 95, 105 and 105 days after harvesting, respectively. However, black seeded variety GT 10 could be utilized for sowing in the next season, as it released the dormancy after at 35 days after harvesting (DAH).