TY  - BOOK
AU  - Pittala Manoj Kumar
AU  - Sindhu, P V(Guide)
TI  - Production technology for enhancing yield and quality of stevia (Stevia rebaudiana Bertoni)
U1  - 630 
PY  - 2025///
CY  - Vellanikkara
PB  - Department of Agronomy, College of Agriculture
KW  - Agronomy
KW  - Production technology
KW  - Stevia
KW  - Stevia rebaudiana Bertoni
N1  - Ph.D
N2  - Stevia rebaudiana is a natural source of steviol glycosides, offering a healthier sugar alternative. Globally, stevia is widely cultivated, and several Indian states have successfully grown it. However, in Kerala, commercial cultivation is limited due to lack of suitable varieties and scientific production technology. To address this, a study entitled “Production technology for enhancing yield and quality of stevia (Stevia rebaudiana Bertoni)” was conducted at the Department of Agronomy, College of Agriculture, Vellanikkara, from 2021 to 2024. The objectives of the study were to collect and characterize stevia accessions based on morphological, biochemical, physiological, and yield parameters, and to standardize nutrient management for growth, yield, and quality.
As part of the first experiment, titled ‘Characterization of Stevia rebaudiana accessions’ twenty-six accessions were collected from different states of the country and were evaluated in a completely randomized design with three replications during October 2021 to January 2022. Significant variability across qualitative, quantitative, and biochemical traits were observed. The plant height ranged from 47.8 to 72.7 cm, and fresh leaf weight ranged from 6.40 to 18.37 g/plant. Accessions exhibited diverse morphological characteristics, particularly in leaf shape and colour as well as stem and inflorescence colouration, which formed the basis for cluster categorization. Gower’s distance method with Ward’s clustering analysis based on leaf traits grouped the accessions into four clusters with 78 per cent dissimilarity, distinguishing oblanceolate leaves with acute tips in Clusters I and II (crenate and incised margins, respectively), and obovate leaves in Clusters III and IV (with obtuse and acute tips, respectively). Based on 14 quantitative characters, accessions were further grouped into three distinct clusters with 66 per cent dissimilarity. Cluster I (12 accessions) exhibited higher trait values, Cluster II (6 accessions) had lower values, and Cluster III (8 accessions) displayed intermediate values.
The principal component analysis (PCA) of 14 quantitative characters revealed that the first four principal components accounted for 85% of the total genetic variability, with PC1 explaining 44% and being influenced by traits like plant height, leaf width, and days to first flowering. Heritability analysis showed 13 out of 14 traits had high heritability, with specific leaf weight and fresh leaf weight exhibiting very high heritability. Fresh leaf weight was strongly correlated with branch and leaf count, and path analysis showed total leaf count had a significant direct effect on fresh leaf weight.
Accessions Acc. 8 (Mala, Thrissur), Acc. 5 (Parappanangadi, Malappuram) and Acc. 13 (IIHR, Bangalore) were superior for leaf yield. Significant biochemical variability was observed among accessions for stevioside, rebaudioside A, and total steviol glycosides (TSGs). Euclidean cluster analysis grouped accessions into four clusters based on biochemical traits, and PCA showed that the first three components explained 83% of the total variability. Acc. 22 (Krishnapuram, Allapuzha), Acc. 9 (Pattikkad, Thrissur), and Acc. 10 (Tammanam, Ernakulam) were identified as superior for TSG content. Combined scoring for leaf yield and TSG content identified Acc. 5 (Parappanangadi, Malappuram), Acc. 8 (Mala, Thrissur), and Acc.7 (Puthenvelikara, Ernakulam) as the most promising accessions with high leaf yield and total steviol glycoside content.
For the standardization of nutrient management for better growth, yield, and quality of stevia, two separate field experiments were conducted, one under an organic management system and the other with an integrated nutrient management system. The experiment on ‘Effect of organic manures on growth, yield, and quality of Stevia rebaudiana was conducted in Randomized Block Design (RBD) with seven treatments and three replications from April to August in 2022 and 2023. The treatments included three levels of farmyard manure (FYM) at 5, 10, and 15 t ha-1 and three levels of vermicompost at 2.5, 5.0, and 7.5 t ha-1, compared with an absolute control. The application of organic manure significantly influenced the growth and yield parameters of stevia. Taller plants with more branches and leaves were observed under FYM @15t ha-1, followed by vermicompost @ 7.5t ha-1 and FYM @10t ha-1. 
The highest fresh herbage yield was recorded under FYM @15t ha-1 (6157 kg ha-1), followed by vermicompost @7.5t ha-1 (5616 kg ha-1). Crop growth and relative growth rates were also superior under FYM @15t ha-1 throughout all the growth stages. The application of vermicompost @2.5t ha-1 resulted in the highest stevioside (5.18 per cent) and total glycoside contents (6.19 per cent), although rebaudioside A (Reb-A) remained unaffected by organic manure treatments. However, concerning total glycoside yield (kg ha-1), the best treatment was vermicompost @2.5t ha-1. The application of FYM @15t ha-1 led to higher soil organic carbon and soil available potassium. On the other hand, soil available nitrogen and phosphorus were highest under vermicompost @7.5t ha-1, followed by FYM @15t ha-1. 
The experiment on integrated nutrient management for stevia was laid out in factorial RBD with three replications during April to August in 2022 and 2023. The treatments included levels of manures as factor A (No manure, vermicompost @2.5t ha-1 and FYM @5 t ha-1) and levels of NPK  as factor B (20:10:10, 40:20:20 and 60:30:30 kg NPK ha-1). The combined application of FYM @5t ha-¹ and NPK @ 60:30:30 kg ha-¹ resulted in the highest growth and fresh herbage yield (5736 kg ha-1). Vermicompost @ 2.5t ha-¹ + NPK @ 40:20:20 kg ha-¹ recorded the highest stevioside (6.04 per cent) and total glycoside (6.45 per cent) contents, while the highest rebaudioside A content was found under FYM @5 t ha-¹ + NPK @20:10:10 kg ha-¹. Combined application of vermicompost @ 2.5t ha-¹ + NPK @ 40:20:20 kg ha-¹  resulted in the highest total glycoside yield (kg ha-1).


UR  - https://krishikosh.egranth.ac.in/handle/1/5810228342
ER  -