MSc

ABSTRACT


Ginger (Zingiber officinale Rosc.) is a herbaceous spice acclaimed for its value in flavour and pharmaceutical industry. A dearth in availability of healthy and good quality planting material is well pronounced in ginger. Hence, a transplant technique, utilizing ginger sprouts raised from small rhizome bits of 3 to 5 g grown in protrays, has been proven to yield on par with conventional planting of 20 g seed rhizome. In such cases, methods to improve vigour and growth of ginger plants, which can result in yield enhancement are highly desirable. The present study, ‘Yield improvement in transplanted ginger by seed priming and biostimulant spray’ was conducted in the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during January 2019 to January 2020 to find out the best priming treatment, optimum concentration of chitosan spray and a combination of both, that improve fresh rhizome yield in transplanted ginger.
In nursery, priming treatments significantly invigorated the growth of sprouts, as evident by the early emergence, high survival per cent and seed vigour index. The emergence of sprouts were early in rhizomes primed with Pseudomonas fluorescens 10 g L-1 for 0.5 hour (6.33 days) followed by hydropriming for one hour (6.83 days). Hydropriming and priming with ethephon 200 ppm for one hour resulted in significantly superior survival per cent of 85.16 and 84.16 respectively. Significantly higher vigour index of seed rhizome was noticed in sprouts subjected to hydropriming and bioprimed with Pseudomonas fluorescens (3167.95 and 3011.99 respectively).
Plant height and tiller production were significantly higher in plants raised from hydroprimed seed rhizome and given foliar sprays of biostimulant chitosan 5 g L-1 at monthly interval for five months, resulting in 74.77 cm height and 16.97 tillers. Invariably, plants subjected to priming or chitosan spray or a combination of both were significantly taller with more number of tillers.
Photosynthetic rate, stomatal conductance and transpiration rate were significantly higher in hydroprimed plants (23.75 µmol m-2 s-1, 2.69 µmol m-2 s-1, 13.67 mmol m-2 s-1 respectively) and in plants sprayed with chitosan 5 g L-1 (23.83 µmol m-2 s-1, 2.78 µmol m-2 s-1, 13.07 mmol m-2 s-1 respectively). Leaf area of ginger was found to be highest in plants primed with Pseudomonas fluorescens (30.76 cm2),
hydropriming (29.68 cm2) and Trichoderma sp. (29.17 cm2). Monthly spraying of chitosan 7 g L-1 was found effective for improving leaf area (30.71 cm2) compared to control (26.72 cm2).
Significantly lowest incidence of Phyllosticta leaf spot was observed in plants sprayed with chitosan 7 g L-1 (25.65%) and 5 g L-1 (30.79%), irrespective of the priming treatments.
Priming and chitosan sprays exhibited significant improvement in fresh rhizome yield of ginger transplants. Significantly highest number of fingers was found in plants sprayed with 5 g L-1 chitosan (12.12). Invariably, all priming treatments were effective in improving the number of fingers. A combination of hydropriming and field spraying of chitosan 5 g L-1 (337.20 g plant-1), biopriming with Pseudomonas fluorescens along with sprays of chitosan 7 g L-1 (335.58 g plant-1) and biopriming with Pseudomonas fluorescens with field spraying of chitosan 5 g L-1 (334.35 g plant-1) were identified as the best three combinations for yield improvement in ginger transplants. All the priming treatments and chitosan sprays recorded significantly higher fresh rhizome yield than the control.
From this study, it is evident that priming of seed rhizomes and foliar application of chitosan can be adopted to improve yield in transplanted ginger. A combined application of priming and foliar sprays of chitosan was found more effective than the individual effect of priming and chitosan. Hence, combination of priming with Pseudomonas fluorescens 10 g L-1 for 30 minutes or hydropriming for one hour, followed by foliar application of chitosan at a concentration of 5 g L-1 at monthly intervals can improve fresh rhizome yield in transplanted ginger.