MSc

Germination and plant growth responses in Ashwagandha (Withania somnifera (L.) Dunal) and Kiriyathu (Andrographis paniculata (Burm.f.) Nees) to seed pretreatments.
The present investigation entitled “Germination and plant growth responses in Ashwagandha (Withania somnifera (L.) Dunal) and Kiriyathu (Andrographis paniculata (Burm.f.) Nees) to seed pretreatments” was conducted in the Department of Plantation Crops and Spices, College of Agriculture, Vellayani during 2018-2020 with the objective to standardize pretreatment of seeds for enhanced germination and plant growth in W. somnifera and A. paniculata.
The seeds of W. somnifera and A. paniculata used for the study were sourced from
Anand Agricultural University, Gujarat, India. The study was carried out in two phases: Phase 1- Pretreatment of seeds for enhanced germination; Phase 2- Evaluation of transplanted seedlings obtained from pretreated seeds for enhanced plant growth. The seeds of W. somnifera and A. paniculata were subjected to various pretreatments viz., physical treatment, hormonal priming, biostimulant priming and biopriming (using microbes). The seeds kept for germination without any pretreatment were taken as the control.
In the first phase of the study in W. somnifera, seeds subjected to water soaking recorded higher germination (84.00 per cent), seedling length (13.30 cm) and seedling vigour index (11.16) which were on par with that of hot water treatment. Among the hormonal priming treatments, seeds exposed to GA3 @1500 μM recorded the highest germination (82.00 per cent), seedling length (14.40 cm) and seedling vigour index (11.80) which were found to be on par with GA3 @1500 μM. In biostimulant seed priming, PG @ 10μM primed seeds recorded higher germination (64.00 per cent), seedling length (10.57cm) and seedling vigour index (6.67) and were found to be on par with those of PG @ 1μM primed seeds. The biopriming treatments had no significant effect on germination and seedling length. However, significantly higher seedling vigour index was observed in all the biopriming treatments over the control treatment. Among all the pretreatments tried, water soaking treatment, hot water treatment, GA3 @ 1500μM was recorded significantly higher germination, seedling length and seedling vigour index.
In the second phase of the study, the 30 day old seedlings of W. somnifera raised from pretreated seeds and untreated (control) seeds were transplanted and evaluated for plant growth and yield (shoot and root biomass), at harvest (120 DAS). Among the physical treatments, W. somnifera plants derived from water soaked seeds were observed to give higher plant height (60.80cm), number of branches (5.00), collar girth (0.47 cm), shoot biomass (fresh-37.61 g plant-1; dry -7.17 g plant-1) and root biomass (fresh-5.60 g plant-1; dry-0.79 g plant-1). These were observed to be on par in plants from hot water treated seeds, except for the number of branches and shoot biomass. Among the hormonal priming treatments, plants from GA3 @ 1500 μM primed seeds recorded higher plant height (55.57cm), shoot (fresh-27.73 g plant-1; dry-5.09 g plant-1) and root (fresh-5.60 g plant-1; dry-0.79 g plant-1) biomass. The plant height and shoot biomass were found to be on par with that of GA3 @ 1500 μM. In biostimulant priming, plants generated from PG @ 10 μM treated seeds gave the highest plant height (46.37 cm), shoot (fresh-21.40 g plant-1; dry-3.96 g plant-1) and root (fresh-4.36 g plant-1; dry-0.64 g plant-1) biomass. The plant height and shoot biomass were observed to be on par with that of PG @ 1μM. However, the highest number of branches and collar girth were recorded in plants raised from PG @ 1μM and SA @ 1500 μM primed seeds. Among the biopriming treatments, plants derived from the seeds treated with B. pumilis, recorded higher plant height (47.63 cm), number of branches (3.00), shoot (fresh-23.07 g plant-1; dry-4.39 g plant-1) and root (fresh-4.43 g plant-1; 0.63 g plant-1) biomass. The plant height and shoot weight was on par with that of P. fluorescens and the plants from the same treatment recorded the highest collar girth. Among the various pretreatments tried, plants raised from water soaked seeds gave better performance with respect to plant height, number of branches, collar girth and shoot biomass. The plants from hot water treated and GA3 @ 1500μM primed seeds gave the highest root biomass, which was observed to be on par with that in plants from water soaked seeds.
In the first phase of the study in A. paniculata, seeds when exposed to physical treatments, higher germination (84.67 per cent), seedling length (15.93 cm) and seedling vigour index (13.38) were recorded in hot water treatment followed by scarification. Among the hormonal priming treatments, GA3 @1500μM primed seeds recorded the highest germination (82.00 per cent), seedling length (16.37 cm) and seedling vigour index (13.42). With respect to biostimulant seed priming, seeds treated with PG @ 1μM recorded higher
germination (66.67 per cent) and seedling vigour index (6.03), while seedling length did not show any variation among the biostimulant treatments. Among the biopriming treatments, seeds primed with B. velezensis recorded the highest germination (82.67 per cent), seedling length (11.33 cm) and seedling vigour index (9.29). In A. paniculata, among all the pretreatments tried hot water treated as well as GA3 @ 1500 μM primed seeds recorded higher germination, seedling length and seedling vigour index.
In the second phase of the study in A. paniculata, the 30 day old seedlings from pretreated seeds and untreated (control) seeds were transplanted and evaluated for plant growth and yield (whole plant biomass) at harvest (110 DAS). Among the physical treatments, A.paniculata plants derived from hot water treated seeds recorded higher plant height (55.77 cm), number of branches (21.67), collar girth (1.83 cm) and whole plant biomass (fresh-59.60 g plant-1; dry-21.90 g plant-1) at harvest. These were on par with those of scarified seeds. In hormonal priming, the highest plant height (56.80 cm), number of branches (20.00), collar girth (1.90 cm) and whole plant biomass (fresh-56.63 g plant-1 and dry-23.60 g plant-1) were observed in plants raised from seeds primed with GA3 @1500μM. Among the biostimulant priming, higher plant height (48.57 cm), number of branches (16.00), collar girth (1.20 cm) and whole plant biomass (fresh-38.97g plant-1 and dry-13.14g plant-1) were observed in plants raised from PG @1 μM primed seeds. On evaluation of plants derived from bioprimed seeds, those from B. velezensis primed seeds recorded the highest plant height (55.77 cm), number of branches (19.33), collar girth (1.50 cm) and whole plant biomass (fresh-53.97 g plant-1; dry16.87 g plant-1). Among all the seed pretreatments tried, plants generated from hot water treated and GA3@1500μM primed seeds recorded higher plant height, number of branches, collar girth and whole plant biomass.
Among the various seed pretreatments tried, W. somnifera seeds exposed to water soaking, hot water and GA3@1500μM and A. paniculata seeds exposed to hot water treatment and GA3@1500μM recorded superior performance with respect to seed germination, seedling vigour, plant growth and yield.