PhD

The present study entitled “Evaluation of Neelayamari (Indigofera tinctoria L.) for yield and glycoside content under open and shaded conditions” was conducted in two phases viz., phase I experiment and phase II experiment. In the phase I experiment, thirty geographical accessions of Indigofera tinctoria collected from inside and outside the Kerala state were raised in lines with two replications each for open as well as shaded condition. Observations on hundred seed weight, seed colour, external appearance of seeds and germination percentage were recorded for each accession. Growth and yield parameters were studied under open and shade under coconut garden. Glycoside content in all the accessions were estimated using fresh leaves, shade dried leaves, oven dried leaves and fermented leaves. A selection index based on leaf yield and glycoside content was worked out to screen the genotypes.
In the phase II experiment, ten accessions, selected based on yield and glycoside content from the phase I experiment were raised in randomized block design in open and under shade with three replications. Growth and yield parameters of the selected accessions were recorded under open as well as under coconut shade similar to phase I experiment. Observations on flowering and seeding behaviour were also made. Root nodule characteristics and physiological parameters were estimated. Soil NPK analysis, plant analysis for nitrogen content and plant analysis for glycoside content were done. Correlation studies were made to find out the factors that contribute to yield and glycoside content. Economics of cultivation of Indigofera tinctoria both in open and under shade in coconut garden was worked out.
Five accessions IT-98, IT-95, IT- 105, IT-108 and IT-106 exhibited more than 80 per cent germination. Of the thirty accessions collected for the study, IT-104 recorded the highest hundred seed weight of 0.56 g. Higher growth parameters were recorded by the accessions IT-108, IT-106 and IT-104, irrespective of open and shaded conditions. Pooled analysis showed that these accessions dominated in the case of shoot, leaf, pod and root, fresh and dry weights also. IT-99 showed superior performance in terms of glycoside content. Among the different leaf treatments, maximum glycoside content was obtained from the fresh leaves. The ten accessions of the blue-green leaved variety of I. tinctoria, which showed superior performance based on selection index scores were IT-108, IT-101, IT-96, IT-114, IT-106, IT-104, IT-105, IT-111, IT-97 and IT-99.
The ten selected accessions from the phase I experiment were put under cultural trial under open and shade in phase II experiment. The accessions IT-108, IT-106, IT-104, IT-101 and IT-96 recorded higher values for all growth parameters. Pooled analysis showed that, the accessions, IT-108, IT-101, IT-106, IT-104 and IT-98 recorded higher shoot and leaf fresh and dry weights at all stages of growth, irrespective of the growing conditions. IT-108 and IT-101 dominated for fresh and dry weight of roots. All the accessions recorded higher values for almost all growth and yield parameters under open condition compared to that under coconut shade.
Flowering in I. tinctoria was observed about 111 days after sowing (DAS) to 116 DAS in open condition and about 117 DAS to 126 DAS under shade. Anthesis was spread over from 8.27 a.m. to 9.12 a.m. under open condition and from 8.46 a.m. to 10.08 a.m. under shade. Pod setting percentage was 20.91per cent under open and 17.3 per cent under shade. Average number of days for pod set was 138 days in open and 148 days under shade. Average number of days for seed maturation was 241 DAS in open and 251 DAS under shade.
Root nodules were found to be present in the roots of I. tinctoria only during the pre-flowering and flowering stages of growth of the plant. Both nodule count and weight was found to be maximum at flowering stage. Number of root nodules and effective root nodules were higher for IT-101 and IT-105. Fresh weight and dry weight of root nodules were higher for IT-108, IT-101 and IT-105. IT-108 produced bigger sized nodules. Both nodule count and weight were found to be higher under open condition.
The accessions IT-101, IT-108, IT-106 and IT-114 recorded higher LAI and LAD at all growth stages. Higher NAR, CGR and RGR were observed in IT-104, IT-101, IT-106 and IT-108. The accessions IT-108, IT-106 and IT-101 recorded higher HI for leaf yield and for leaf and root yield. HI for root yield was maximum for IT-97, IT-108 and IT-101. Irrespective of the growing condition, the accessions IT-105 fixed comparatively higher soil nitrogen, followed by IT-101. Soil nitrogen content was found to be lower under shade than in open. Pooled mean for plant N content was maximum for IT-108 followed by IT-96, IT-105 and IT-101.
IT-99 showed superior performance in terms of glycoside content. Plants of all accessions grown in open condition recorded higher glycoside content compared to shade. IT-96, IT-99, IT-114 and IT-106 recorded the maximum value for indigo content. Shade grown plants recorded lower indigo content compared to open.
The phenotypic and genotypic correlation coefficients under open conditions were estimated for nineteen pairs of characters. The extent of association between yield and glycoside content with other characters was measured by genotypic and phenotypic correlation coefficients. High positive phenotypic and genotypic correlation of leaf yield (dry weight) was observed with shoot yield (dry weight), leaf area, leaf area index, dry matter accumulation per plant and girth of stem and negative correlation with glycoside content and indigo content. Glycoside content was found to show high positive phenotypic and genotypic correlation with indigo content. Most of the other characters showed negative correlation with glycoside content.
Indigo content, dry weight of root, HI (root yield), dry weight of leaves, net assimilation rate and dry weight of shoot showed high GCV and PCV compared to other characters. PCV was higher in magnitude than GCV. In the present investigation, leaf area, dry weight of shoot, dry weight of leaves and dry matter accumulation per plant had high heritability and high genetic advance. Therefore these traits are highly amenable to direct selection for their genetic improvement.
Benefit-cost analysis showed that, for every one rupee spend on the crop, the net returns was found to be 3.05 in open condition and 2.34 under shade. The accession IT-108 showed superior performance in terms of leaf yield and glycoside content followed by IT-101 and IT-96. NAR, CGR, AGR, RGR etc. were found to be highest in open condition, which indicates that for optimum growth it prefers open condition compared to shade. But benefit- cost analysis indicates that the crop can be cultivated as a profitable enterprise, both in open condition and under coconut shade, the net income being less under shaded condition.