Growth, yield and essential oil production responses to microbial elicitation in Ocimum basilicum L.

Abstract

The seeds of O. basilicum used for the study were sourced from Anand Agricultural University, Gujarat. The study was carried out in two phases: Phase 1- Seed priming using fungal derivatives for enhanced germination. Phase 2- Evaluation of the effect of foliar application of fungal derivatives for growth, yield and essential oil production. In the first phase of study, the seeds were subjected to various priming treatments using fungal derivatives viz., Trichoderma viride cell wall extract (1 %) (TCWE), Trichoderma viride culture filtrate (1 %) (TCF), Piriformospora indica cell wall extract (1 %) (PCWE), Piriformospora indica culture filtrate (1 %) (PCF) and hydro priming, maintained upto 30 days after sowing. The seeds without any priming were taken as the absolute control. In the second phase of study, the 30 days old seedlings of O. basilicum were transplanted to grow bags. The foliar spray of corresponding fungal derivatives (cell wall extract and culture filtrate) at 1 % concentration were given to plants at fortnightly intervals from transplanting to 90 days after sowing. The treatment without any foliar application was taken as the absolute control. The seeds bioprimed with PCF @ 1 per cent recorded the highest germination per cent (96%), survival per cent (96%) and had taken minimum number of days (3 days) to initial sprouting. While TCF @ 1 per cent exhibited the highest germination index (34.50) and lowest mean germination time (6.29 days). With regard to seedling development, PCF @ 1 per cent recorded a significantly higher shoot length (21.50 cm), root length (19.50 cm), seedling length (41.00 cm) and seedling vigour index (39.37). The highest (1.07) allometric index was observed in the treatment PCWE @ 1 per cent. At 110 DAS, the plants subjected to foliar application with PCF @ 1 per cent exhibited higher plant height (80.20 cm), collar girth (6.03 cm), leaf area (4010.82 cm2 ), number of branches (28.00) and number of flowering shoots (104.00). The same treatment induced early flowering (55 days) in O. basilicum. The foliar spray treatment with PCF @ 1 per cent exhibited significantly higher total chlorophyll content (1.20 mg g-1 ) and polyphenol content (84.31 mg PE g-1 ) at 110 DAS. The plants subjected to foliar application with PCF @ 1 per cent recorded maximum leaf biomass (210.00 g and 19.04 g), stem biomass (135.33 g and 12.21 g), herbage yield (345.33 g and 31.25 g), root biomass (52.00 g and 4.63 g) and total plant biomass (397.33 g and 35.88 g) respectively, on both fresh weight and dry weight basis. The same treatment recorded the highest leaf biomass (125.33 g and 12.44 g), stem biomass (76.00 g and 7.31 g), and herbage yield (201.33 g and 19.75 g), on fresh weight and dry weight basis respectively, in the ratoon crop harvested 60 days after the first cut. PCF @ 1 per cent was also observed to give the highest essential oil content (2.11 per cent and 1.00 per cent) and oil yield (443.10 g and 19.04 g, respectively) in terms of both fresh and dry leaf weight. This is followed by PCWE @ 1 per cent and TCF @ 1 per cent in terms of oil content and yield. In the first phase of study, PCF @ 1 per cent gave better performance in terms of seed germination, seedling growth and seedling vigour index. The transplanted seedlings from the same treatment when subjected to foliar application with PCF @ 1 per cent at fortnightly intervals gave the highest plant growth, biochemical and yield parameters in the second phase of study. Hence, it can be inferred that biopriming followed by foliar application of the fungal derivative PCF @ 1 per cent would give superior performance in terms of plant growth, yield and essential oil production in O. basilicum.