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Central Agricultural University, College of Post Graduate Studies in Agricultural Sciences, Umiam

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2011 - 20183
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Author: Sangma, Christy Berylnight K. ×
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    ThesisItemOpen Access
    Development of native Rhizobium compatible enriched compost for use in Lentil (Lens culinaris Medik.) grown in Acid Soil.
    (College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam, 2018-09) Sangma, Christy Berylnight K.; Thakuria, Dwipendra
    The benefit of Rhizobium inoculation in pulse crops grown near neutral to slightly acidic soils is well known. The promotion of pulse crops, especially lentil (Lens culinaris Medik.) in acid soils of North East India is very challenging due to poor nodulation efficiency and nitrogen fixation in strongly acid soils. Out of several causes, the development of acidity tolerant Rhizobium strain and build-up of Rhizobium population near the germinating seeds (spermosphere) in acid soils are challenging tasks. This investigation aimed at the development of effective native Rhizobium leguminosarum strain tolerant to acid soil and delivery of the effective Rhizobium strain through enriched compost to the soil. In order to prepare enriched compost, effective cellulose degrading bacteria (CDB) were screened and the most effective one used for preparation of compost followed by its enrichment by application of efficient Rhizobium strain and phosphate solubilising bacteria (PSB) along with rock phosphate (RP). Cellulose degrading bacteria were isolated from the forest floor litters of jhum cycles 2, 5, 10, and 20 years using cellulose agar medium (CAM) and were screened for cellulase activity in agar plates containing carboxy-methyl-cellulose (CMC) as substrate. Out of 32 CDB isolates, the most effective one (CDM-C1) was used for enrich compost preparation. Pea plant grown in 4 soil types (organic farm plot of ICAR, Umiam; Monabari, Garo Hills; Soils from Upland Lowland of CPGS farm fields) were screened for nodules. R. leguminosarum bv. viceae isolates were grow non Yeast Extract Mannitol Agar (YEMA). R. leguminosarum isolates were further confirmed on CRYEMA containing congo red. Four native Rhizobium isolates (NR1, NR2, NR3 and NR4) including one reference exotic strain (ER), Rhizobium leguminosarum CK1 (obtained from AINP Solan Centre, Dr. YSPUH & F, Solan, HP,India) were screened for nodulation efficiency and yield enhancement on lentil crop grown in a pot experiment using an acid soil (pH 5.25). The treatment combinations of the pot experiment were: (1) SRE 1: negative control (no Rhizobium inoculation)+50%RDF (@ 10:30:10 kg N-P-K ha-1), (2) SRE 2: positive control(CK1)+50% RDF, (3) SRE 3: NR1+50%RDF, (4) SRE 4: NR2+50%RDF, (5) SRE 5:NR3+50%RDF and (6) SRE 6: NR4+50%RDF. The treatment SRE4 (native Rhizobium NR2) performed best in terms of plant height, no. of branches, nodulation efficiency and yield compared to other treatments (P≤0.05, one-way ANOVA). Inoculum of the most effective CDM-C1 isolate was applied into mixed biomass (Eupatorium spp., Ambrosia spp. and broom grass and crop residues like rice straw, maize stalk and banana leaves) for preparation of compost in standard pits (each pit size was 1m x 1m × 1m) by imposing 5 treatments: (1) Normal compost 1 (EC1), (2) enriched compost (EC 2): RP+PSB compost, (3) enriched compost (EC 3): NR2 compost (4) enriched compost (EC 4): RP+PSB+NR2 compost, and (5) enriched compost (EC 5): RP+PSB+ER(CK1) compost. The compost quality and nutrient contents (E4/E6, ash content and alkalinity, germination percentage and index, N, Pand K content, pH and EC) values indicated that EC4 and EC5 composts were better than EC1 and other enriched compost. A field experiment on lentil crop (variety PL-8)was conducted in the ICAR Experimental Farm, Umiam with 9 treatments combination:T1: 100% RDF (@20:60:20 kg N-P-K ha-1), T2: 50% RDF, T3: seed inoculation (SI) with NR2+EC 1+50% RDF, T4: SI with ER (CK1)+EC 1+50% RDF, T5: SI with NR2+EC 2+50% RDF, T6: SI with ER (CK1)+EC 2+50% RDF, T7: SI with NR2+EC 4+50% RDF, T8: SI with ER (CK1)+EC 5+50% RDF, T9: SI with NR2+ EC 3+50% RDF. The nodulation efficiency was the highest in T5 followed by T7. Pod and seed yield were the highest in T5 followed by T7 and these treatments received enriched compost amended with native Rhizobium (NR2), PSB and RP. Overall, it can be concluded that enriched compost amended with native Rhizobium, PSB and RP showed great potential in supporting higher nodulation efficiency and yield of lentil crop grown under acid soil. Key words: Cellulose decomposer; Jhum; native Rhizobium; Acid soil; Pulse promotion; Lentil.
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    ThesisItemOpen Access
    Characteristics of biological pools of carbon, nitrogen and phosphorous in soils of rice ecosystems in Meghalaya
    (College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam, 2011) Sangma, Christy Berylnight K.; Thakuria, Dwipendra
    Soil ecosystems are complex and biogeochemistry of soils is governed largely by the functioning of soil biota community through their control over the biological pool of every elemental cycle. Biological pools of carbon (C), nitrogen (N) and phosphorus (P) in soils of hill rice ecosystems in North East India are not yet characterized. This study characterized an array of biological parameters of C, N and P in soils of three common rice ecosystems viz. slope land, upland terrace and lowland. Soil samples (0-15 cm depth) were collected from six different sites located in two villages (Saiden and Kyrdemkulai) in post-summer and in post-winter seasons. The soil of each site differed significantly between seasons in terms of soil microbial biomass C, N and P, total and dissolved organic carbon, extractable organic nitrogen, potentially mineralizable nitrogen, basal and substrate induced respiration, total N and P, available N and P, soil dehydrogenase and phosphates activities (P  0.01, n=20 as determined by paired t-test within a site) and these parameters were strongly influenced by soil moisture content. Pair-wise correlation matrix analysis revealed that biological parameters of C, N and P were strongly influenced by each other (correlation coefficient r ≥ 0.36 at P0.05, or ≥0.46 at P0.01, n=30). Principal component analysis (PCA) performed season-wise considering the biological parameters as defined variables indicated that rice fields were grouped according to ecosystem type and soil moisture status, and such effects overrides the impacts of site differences in biological pools of C, N and P. Moisture content in soils observed to be a critical variable in hill rice ecosystems that control the size and dynamics of biological pools of C, N and P and the interrelationships among these parameters. Overall, it can be concluded that C and N components of soils in lowland and stabilized upland terrace rice ecosystems seem to be self-sustained, but the major limiting factor was availability of P.
  • Thumbnail Image
    ThesisItemOpen Access
    Development of native Rhizobium compatible enriched compost for use in Lentil (Lens culinaris Medik.) grown in Acid Soil.
    (College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam, 2018-09) Sangma, Christy Berylnight K.; Thakuria, Dwipendra
    The benefit of Rhizobium inoculation in pulse crops grown near neutral to slightly acidic soils is well known. The promotion of pulse crops, especially lentil (Lens culinaris Medik.) in acid soils of North East India is very challenging due to poor nodulation efficiency and nitrogen fixation in strongly acid soils. Out of several causes, the development of acidity tolerant Rhizobium strain and build-up of Rhizobium population near the germinating seeds (spermosphere) in acid soils are challenging tasks. This investigation aimed at the development of effective native Rhizobium leguminosarum strain tolerant to acid soil and delivery of the effective Rhizobium strain through enriched compost to the soil. In order to prepare enriched compost, effective cellulose degrading bacteria (CDB) were screened and the most effective one used for preparation of compost followed by its enrichment by application of efficient Rhizobium strain and phosphate solubilising bacteria (PSB) along with rock phosphate (RP). Cellulose degrading bacteria were isolated from the forest floor litters of jhum cycles 2, 5, 10, and 20 years using cellulose agar medium (CAM) and were screened for cellulase activity in agar plates containing carboxy-methyl-cellulose (CMC) as substrate. Out of 32 CDB isolates, the most effective one (CDM-C1) was used for enrich compost preparation. Pea plant grown in 4 soil types (organic farm plot of ICAR, Umiam; Monabari, Garo Hills; Soils from Upland Lowland of CPGS farm fields) were screened for nodules. R. leguminosarum bv. viceae isolates were grow non Yeast Extract Mannitol Agar (YEMA). R. leguminosarum isolates were further confirmed on CRYEMA containing congo red. Four native Rhizobium isolates (NR1, NR2, NR3 and NR4) including one reference exotic strain (ER), Rhizobium leguminosarum CK1 (obtained from AINP Solan Centre, Dr. YSPUH & F, Solan, HP,India) were screened for nodulation efficiency and yield enhancement on lentil crop grown in a pot experiment using an acid soil (pH 5.25). The treatment combinations of the pot experiment were: (1) SRE 1: negative control (no Rhizobium inoculation)+50%RDF (@ 10:30:10 kg N-P-K ha-1), (2) SRE 2: positive control(CK1)+50% RDF, (3) SRE 3: NR1+50%RDF, (4) SRE 4: NR2+50%RDF, (5) SRE 5:NR3+50%RDF and (6) SRE 6: NR4+50%RDF. The treatment SRE4 (native Rhizobium NR2) performed best in terms of plant height, no. of branches, nodulation efficiency and yield compared to other treatments (P≤0.05, one-way ANOVA). Inoculum of the most effective CDM-C1 isolate was applied into mixed biomass (Eupatorium spp., Ambrosia spp. and broom grass and crop residues like rice straw, maize stalk and banana leaves) for preparation of compost in standard pits (each pit size was 1m x 1m × 1m) by imposing 5 treatments: (1) Normal compost 1 (EC1), (2) enriched compost (EC 2): RP+PSB compost, (3) enriched compost (EC 3): NR2 compost (4) enriched compost (EC 4): RP+PSB+NR2 compost, and (5) enriched compost (EC 5): RP+PSB+ER(CK1) compost. The compost quality and nutrient contents (E4/E6, ash content and alkalinity, germination percentage and index, N, Pand K content, pH and EC) values indicated that EC4 and EC5 composts were better than EC1 and other enriched compost. A field experiment on lentil crop (variety PL-8)was conducted in the ICAR Experimental Farm, Umiam with 9 treatments combination:T1: 100% RDF (@20:60:20 kg N-P-K ha-1), T2: 50% RDF, T3: seed inoculation (SI) with NR2+EC 1+50% RDF, T4: SI with ER (CK1)+EC 1+50% RDF, T5: SI with NR2+EC 2+50% RDF, T6: SI with ER (CK1)+EC 2+50% RDF, T7: SI with NR2+EC 4+50% RDF, T8: SI with ER (CK1)+EC 5+50% RDF, T9: SI with NR2+ EC 3+50% RDF. The nodulation efficiency was the highest in T5 followed by T7. Pod and seed yield were the highest in T5 followed by T7 and these treatments received enriched compost amended with native Rhizobium (NR2), PSB and RP. Overall, it can be concluded that enriched compost amended with native Rhizobium, PSB and RP showed great potential in supporting higher nodulation efficiency and yield of lentil crop grown under acid soil.