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Open Access
Cytogenetic studies on intervarietal hybrids of sesamum (Sesamum indicum L.)
(Department of Agricultural Botany, College of Agriculture Vellayani, Trivandrum., 1984) Chandramony, D; KAU; Krishnan Nair, N
Open Access
Enhancement of propagation efficiency in exotic varities of heliconia
(Department of Pomology and Floriculture, College of Agriculture, Vellayani, 2008) Reshmi, C R; KAU; Sheela, V L
Heliconias are among the most popular garden plants, both for the ease with which they can be grown and the sheer magnificence of the blooms. Studies were conducted to standardize rapid propagation techniques under in vitro and in vivo conditions. Three heliconia varieties belonging to three distinct groups viz., St. Vincent Red (small erect type), Golden Torch Adrian (hybrid) and Sexy Pink (large pendent type) were selected for the study. For in vitro culture establishment, shoot tip explants were effective. The treatment of shoot tips with 0.10 per cent mercuric chloride for ten minutes followed by dipping in 0.05 per cent mercuric chloride for five minutes (after trimming) resulted in better surface sterilization. Longitudinal cutting of the in vitro established shoot tip with apical dome into two halves and culturing them separately produced the highest number of axillary buds. Addition of 0.05 per cent activated charcoal to the establishment media reduced the media browning and hastened shoot initiation. For culture establishment of all the three varieties, MS medium supplemented with BA 5.00 mg l-1 was found to be the best. Murashige and Skoog medium supplemented with BA 2.00 mg l-1 resulted in the highest shoot proliferation in the variety St. Vincent Red. In Golden Torch Adrian, BA 2.00 mg l-1 + NAA 0.20 mg l-1 gave better results. In the variety Sexy Pink, Kinetin 5.00 mg l-1 + NAA 0.20 mg l-1 was the best. For further multiplication in Sexy Pink, BA 1.00 mg l-1 was sufficient. Solid culture medium was better for shoot proliferation in the variety Sexy Pink. Higher sucrose concentration (40.00 g l-1) increased the multiplication rate, but reduced the length of shoots as well as the number of leaves. Addition of activated charcoal to the media as well as exposure of cultures to light had negative effect on shoot proliferation. Full MS medium was found to be the best for in vitro rooting of the variety Sexy Pink. Addition of NAA 0.50 mg l-1 to the MS medium gave better results for in vitro rooting in Golden Torch Adrian and Sexy Pink. Sucrose @ 30.00 g l-1 was sufficient for in vitro rooting in the variety Sexy Pink. Activated charcoal delayed root initiation and reduced the number of roots in the variety Sexy Pink. Sand recorded 90.00 per cent survival in all the three varieties after two months of planting out. At varietal level, significant difference was evident in the total number of suckers. In the first experiment, the variety St. Vincent Red (3.82) was significantly superior in terms of total number of suckers. However, in the second experiment, St. Vincent Red (4.06) was on par with Golden Torch Adrian (4.10). The variety Sexy Pink produced comparatively taller suckers in both the trials. Varietal variation in the number of leaves was observed only in the earlier stages. During the preliminary field experiment, the variety Sexy Pink excelled in leaf area at almost all stages of observation. Among the three varieties, highest collar girth was recorded by suckers of Sexy Pink variety during the first two stages of observation. However, towards the later stages, it was statistically on par with St. Vincent Red. Foliar spray was superior to rhizome dip in terms of total number of suckers, height of suckers and the number of leaves. In the case of leaf area, both the treatments were more or less on par. Application of growth regulators had pronounced effect on sucker production at all the stages during the first experiment when BA 750 mg l-1 produced the highest number (4.19) of total suckers. In the second experiment, variation was evident only in the total number of suckers. Here, BA 850 mg l-1 produced the highest number (4.33) of suckers and it was on par with BA 700 mg l-1 (4.00) and GA3 650 mg l-1 (3.79). Irrespective of the stage of plant growth, gibberellic acid produced taller suckers and BA 500 mg l-1 resulted in the shortest suckers. BA treatments recorded comparatively higher number of leaves. Growth regulator application had remarkably influenced the leaf area of suckers also. Application of BA 1000 mg l-1 (3.53 cm) and GA3 800 mg l-1 (3.33 cm) recorded higher collar girth in suckers. VG interaction exerted significant variation in the number of suckers. At varietal level, BA 750 mg l-1 produced the highest number of suckers in St. Vincent Red (4.75), GA3 500 mg l-1 in Golden Torch Adrian (4.63) and GA3 750 mg l-1 in Sexy Pink (4.00). Among VG treatment combinations in the second experiment, the highest number of suckers (4.75) in the variety St. Vincent Red was produced by BA 700 mg l-1. The varieties Golden Torch Adrian (4.88) and Sexy Pink (3.75) recorded the highest with BA 850 mg l-1. Gibberellic acid produced taller suckers. In the second experiment, VG interaction had no significant effect on the height of suckers. Regarding the number of leaves, BA resulted in comparatively higher number of leaves in both the experiments. In all the three varieties, BA 850 mg l-1 produced the highest number of leaves. Collar girth was found to increase with increase in the concentrations of BA and GA3 in all the three varieties. The economics of foliar application of growth regulators revealed that BA 850 mg l-1 significantly enhanced the profit in the varieties Golden Torch Adrian and Sexy Pink. Although negligible, BA 700 mg l-1 recorded slight positive response in the variety St. Vincent Red with respect to profit.
Open Access
Development of F1 hybrids of indeterminate tomato (Solanum lycopersicum L.) for protected cultivation
(Department of Olericulture, College of Agriculture, Vellayani, 2015) Lekshmi, S L; KAU; Celine, V A
The present investigation entitled “Development of F1 hybrids of indeterminate tomato (Solanum lycopersicum L.) for protected cultivation” was conducted at the Department of Olericulture, College of Agriculture, Vellayani, from 2013 to 2015 with the objectives of identifying superior varieties and developing F1 hybrids of indeterminate tomato suited for protected cultivation. The study consisted of two experiments conducted in the naturally ventilated polyhouse of size 50 m x 20 m located at the Instructional Farm, Vellayani. In the first part of the first experiment, 40 tomato genotypes were evaluated for two consecutive years in an RBD with three replications. As the second part, 12 commercial hybrids were evaluated. The second experiment consisted of a 9 x 9 half diallel analysis laid out in an RBD with three replications. Analysis of variance showed significant differences between the genotypes for all the characters for two crops. Pooled analysis revealed that, LE 1 recorded the highest yield (2443.43 g) and fruit weight (108.13 g) followed by LE 7. LE 53 had maximum number of fruits per plant (65.00). In the present study, genotypes had wide variation for quality parameters. Fruits of LE 14 recorded highest TSS with a mean of 5.74 ºBrix. LE 7 had maximum ascorbic acid (30.13 mg/100g) and lycopene content (13.09 mg/100g). Beta carotene value was maximum in LE 16 (184.15 mg/100g). There was minimum incidence of pests, diseases and physiological disorders under protected conditions. Among the 12 hybrids evaluated, INDAM 9802 was the highest yielder (1444.40 g) followed by F1 T 30 (1412.22 g). F1 T 30 recorded maximum fruits per plant (35.66) which was on par with F1 Queen (35.55). Genetic parameters like phenotypic and genotypic coefficients of variation, heritability and genetic advance were studied to assess the genetic variability among the genotypes. High heritability coupled with high genetic advance were observed for characters like truss per plant, fruits per truss, fruit weight, fruits per plant, yield per plant and yield per plot. Path analysis revealed highest positive direct effect for fruit weight (0.3956), truss per plant (0.3558) and fruits per plant (0.3381). Based on D2 analysis the 40 genotypes were grouped into eight clusters. Cluster I was the largest with twenty four genotypes followed by cluster II with ten genotypes. Diallel analysis was carried out using nine parents selected based on genetic divergence and per se performance. The parents were crossed in a diallel fashion excluding reciprocals to obtain 36 F1 hybrids. The study revealed that P5 x P9 had the highest yield (3114.03 g) which was on par with P6 x P8 (3074.37 g) and P1 x P5 (3077.58 g). P1 x P5 had the maximum fruits per plant (103.93). The magnitude of relative heterosis, heterobeltiosis and standard heterosis varied considerably. For yield, relative heterosis ranged from -32.40 to 92.72, heterobeltiosis from -47.14 to 89.54 and standard heterosis from 2.91 to 160.95. The σ2gca and σ2sca ratio indicated that non-additive gene action was predominant for all traits. Among the nine parents, P9 (LE 1), P5 (LE 20) P1 (LE 2), and P2 (LE 7) were superior for yield and yield attributes. The estimates of sca effects indicated that P5 x P9 (LE 20 x LE 1), P6 x P8 (LE 39 x LE 38) and P1 x P5 (LE 2 x LE 20) were the most promising hybrids for protected cultivation. The present study revealed that the genotypes LE 1 and LE 7 and the hybrids INDAM 9802 and F1 T 30 were superior for yield and yield attributes under protection. Based on the mean performance, standard heterosis and sca effects the three potential crosses viz., P5 x P9, P6 x P8 and P1 x P5 could be adjudged as suitable indeterminate tomato hybrids for protected cultivation.
Open Access
In vitro propagation and rapid analysis of selected varieties of papaya (carica papaya L)
(Department of Pomology and Floriculture, College of Agriculture, Vellayani, 2007) Bindhu, B; KAU; Jayachandran Nair, C S
A study was carried out at the Department of Pomology and Floriculture, College of Agriculture, Vellayani during 2003-2006 for refining existing tissue culture protocol with respect to selected varieties and hybrids of papaya. Molecular characterization of papaya hybrids was also carried out using Random Amplified Polymorphic DNA (RAPD) technique. Papaya varieties and hybrids selected for the study were Pusa Nanha, CO-5, Washington, Pusa Nanha x Coorg Honeydew, Pusa Dwarf x Coorg Honeydew, Solo x Coorg Honeydew and Pusa Nanha x Solo. Apical buds and lateral buds from seedlings and mature plants were used as explant for in vitro propagation. The present study revealed that full strength MS medium supplemented with sucrose 30.00 g l-1 and agar 6.00 g l-1 under light condition produced highest shoot number and longest shoot in papaya varieties and hybrids. Application of BA 0.50 mg l-1 along with NAA 0.10 mgl-1 was found to be better for initial culture establishment and proliferation of papaya varieties and hybrids. Application of amino acid, arginine 50.00 mg l-1 resulted in highest shoot proliferation rate, while highest shoot length was obtained from arginine 100.00 mg l-1. Addition of activated charcoal 0.05 per cent and Cobalt chloride 10.00 mg l-1 increased shoot proliferation rate and shoot length in papaya varieties and hybrids. In vitro rooting was best in full strength MS medium supplemented with IBA 3.00 mg l-1, sucrose 30.00 g l-1and activated charcoal 0.05 per cent. Earliest planting out of in vitro propagated plants in potting media was carried out in papaya variety Pusa Nanha and late planting out in papaya hybrid Pusa Nanha x Coorg Honeydew. Highest plant height of in vitro propagated plants, at time of planting out in potting media was recorded by papaya variety Washington and lowest by papaya hybrid Pusa Nanha x Coorg Honeydew, while hsighest leaf number was reported from papaya variety CO-5 and lowest from Pusa Nanha. But longest root was noticed in papaya hybrid Pusa Nanha x Coorg Honeydew and shortest root from CO-5. No significant difference was noticed in the number of roots produced at the time of planting out in potting media. In vitro propagated plants of papaya had better establishment in the potting mixture containing sand : soil : cowdung (1 : 1 : 1) + Mycorrhiza (1.00 g plant -1). After field establishment, highest plant height and plant girth was noticed in papaya variety Washington and lowest in papaya hybrid Pusa Dwarf x Coorg Honeydew. While highest leaf number upto six weeks after planting was shown by papaya variety CO-5 and thereafter by papaya variety Washington. Lowest leaf number upto eight weeks after planting was noticed in papaya hybrid Solo x Coorg Honeydew and thereafter by papaya hybrid Pusa Dwarf x Coorg Honeydew. Early flowering was reported in papaya hybrid Pusa Dwarf x Coorg Honeydew and late flowering in papaya variety Washington. Most of the papaya varieties and hybrids selected for the present study exhibited only dioecious nature, but papaya hybrid Solo x Coorg Honeydew showed gynodioecious nature. Highest field establishment of in vitro propagated plants was shown by papaya varieties CO-5 and Washington and lowest by papaya hybrid Solo x Coorg Honeydew. Genomic DNA was successfully isolated from four papaya hybrids using CTAB method. All the ten primers (six primers from OPA and four primers from OPB series) yielded amplification products with isolated DNA. A total of 39 RAPDs were obtained from ten primers of which 36 bands were polymorphic. Primers OPA-03, OPA-04, OPA-12, OPB-04 and OPB-17 gave 40 scorable bands, with an average of 8.0 bands per primer. The largest cluster in dendrogram was formed by three hybrids - Pusa Nanha x Coorg Honeydew, Pusa Dwarf x Coorg Honeydew and Pusa Nanha x Solo. The second cluster contained only one hybrid - Solo x Coorg Honeydew. The minimum similarity coefficient detected in the present study was 0.389, suggesting a genetic differentiation among the papaya hybrids.
Open Access
Induced mutations in banana var. Nendran
(Department of Agricultural Botany, College of Agriculture, Vellayani, 1990) Radha Devi, D S; KAU; Krishnan Nair, N
The present investigations was carried out in the Department of Agricultural Botany, College of Agriculture, Vellayani during 1985-88 and in the plant tissue culture Laboratory attached to the Department of Plantation Crops, College of Horticulture, Vellanikkara, Thrissur during 1986-88. The project was taken up to standardise the techniques for induced mutagenesis in-vitro and in-vitro in banana (Musa paradiciaca L.) var. nendran and aslo to analyse the direct effect of 60 Co gamma rays on growth and bunch characters in the vM1 and vM3 generations. One, two and three months old suckers of various sizes (after removal of 25 to 75 per cent of the pseudostem) were exposed to 1.0, 1.5, 2.0, 2.5 and 3.0 kR gamma rays. For in-vitro mutagenesis, isolated shoot tips were exposed to 0.50, 0.75, 1.00, 1.25 and 1.50 kR gamma rays. Ex-vitro analysis of five plants per treatment per exposure was done in the vM1 generation for various growth, bunch and fruit characters.
Open Access
Studies on heterosis and combining abilities with respect to important economic traits in Capsicum annuum, L.
(Division of Agricultural Botany, College of Agriculture, Vellayani, 1981) Manikantan Nair, P; KAU; Mary, K George
Sixty three varieties of Capsicum annuum representing different agroclimatic regions of the country constituted the base material of the study. Based on yield potential , adaptability and tolerance to leaf curl complex disease, thirty varieties were selected for subsequent studies. Comprehensive genetic studies including estimation of genetic parameters, cause effect relationship by path coefficient analysis, genetic divergence by Mahalanoble D2 statistic and a nine parent diallel analysis to causes the combining ability, to unravel the pattern of inheritance and also to examine the level of heterosis manifested with respect to eighteen economic characters including four nutritiveand quality attributes namely Vitamin A, Vitamin C, Capsaicin and Oleoresin content were conducted during the year 1976-79. Analysis of plot means exhibited highly significant differences among varieties except for Capsaicin content. The high degres of variability in economic attributes offers scope for recombining desirable genes from different varieties.
Open Access
Biometric analysis of yield and certain yield attributes in the para rubber tree: Hevea Brasiliensis Muell. Arg.
(Department of Agricultural Botany, College of Agriculture, Vellayani, 1984) Markose, V C; KAU; Mary, K George
The para rubber tree, Hevea brasiliensis, is the commercial source of natural rubber. Introduced into the Far East in 1876, from Brazil, commercial cultivation started in India during 1902. The tree has a gestation period of six to seven years. A large number of clones have been evolved through ortet selection and through hybridisation, which show variability for different characters. The present study was undertaken to estimate (1) productivity (2) yield pattern (3) variability (4) correlations (5) effect of yield attributes (6) genetic diversity of twenty clones, and (7) early growth vigour of open pollinated seedlings of selected clones.
Open Access
Development of chilli (capsicum annuum l.) hybrids with leaf curl virus resistance, high yield and quality
(Department of Vegetable Science, College of Agriculture , Vellayani, 2019) Vijeth, S; KAU; Sreelathakumary, I
The investigation entitled “Development of chilli (Capsicum annuum L.) hybrids with leaf curl virus resistance, high yield and quality” was carried out at the Department of Vegetable Science, College of Agriculture, Vellayani, during the period of 2015-2018. The study was aimed at identification of sources for chilli leaf curl virus (ChiLCV) resistance, development of chilli hybrids with ChiLCV resistance, high yield and quality and studying the gene action of ChiLCV resistance. The investigation was conducted in four experiments. In experiment I (a), 70 chilli genotypes were evaluated for yield and quality traits. The best genotypes based on per se performance were CHIVAR-9 for plant height (73.33 cm), CHIVAR-4 for primary branches plant-1 (4.77), Jwalasakhi for days to first harvest (42.00 days), CHIVAR-7 for fruits plant-1(137.33), Vellayani Athulya for days to first flower (26.94 days), fruit length (8.50 cm), fruit girth (4.78 cm) and fruit weight (7.57 g), CA-32 for yield plant-1 and yield plot-1 (587.33 g and 16.10 kg/6.48m2 respectively), Punjab Sindhuri for vitamin C (120.33 mg 100 g-1) and Byadagi Kaddi for carotenoids (331.33 mg 100 g-1). Seven genotypes viz., CHIVAR-3 (L1), CHIVAR-7 (L2), CHIVAR-6 (L3), CA-32 (L4), Vellayani Athulya (L5), Keerthi (L6) and CHIVAR-10 (L7) were selected based on selection index ranking for utilization as lines in line (L) × tester (T) analysis. Among the 70 genotypes screened against ChiLCV under field condition [experiment I (b)], 23 were moderately susceptible, 12 each were susceptible and moderately resistant, ten were symptomless, six were resistant, five were highly resistant and two were highly susceptible. The selected ten symptomless and five highly resistant genotypes were subjected to artificial screening by using whitefly mediated and graft inoculations in experiment II (a). Six genotypes were symptomless under whitefly mediated inoculation, among which, four genotypes viz., Sel-3, Sel-4, Sel-6 and CHIVAR-1 showed highly resistant reaction under graft inoculation. The resistant genotypes identified under artificial inoculation by Polymerase Chain Reaction (PCR) using universal primers (AV494/AC1048) for the confirmation of ChiLCV. All the graft inoculated genotypes showed presence of virus. However, in the whitefly mediated inoculation, four genotypes viz., Sel-3 (T1), Sel-4 (T2), Sel-6 (T3) and CHIVAR-1 (T4) did not show any amplification for presence of virus. Hence, they were used as testers (male parent) in line (L) × tester (T) analysis. The overall disease score was higher with graft inoculation than whitefly mediated inoculation. The BLAST analysis of the amplified sequence showed 93 per cent similarity to Tomato leaf curl Karnataka virus (ToLCKV). Seven genotypes (lines) with high yield and quality attributes were crossed with four highly resistant genotypes (testers) in line (L) × tester (T) mating design in experiment III (a) to produce 28 F1 hybrids. These hybrids were evaluated along with parents and two checks (CH-27 and Arka Harita) for yield and quality attributes and ChiLCV resistance during summer in 2017 [experiment III (b)]. Based on per se performance most promising hybrids were L3 × T2, L6 × T1, L1 × T1, L7 × T1 and L3 × T1 for yield traits and L4 × T1, L4 × T2, L4 × T3 and L7 × T1 for quality traits. The superior crosses based on heterobeltosis, standard heterosis and SCA effects were L3 × T2, L1 × T1, L7 × T1, L6 × T1, L3 × T1, L2 × T4, L4 × T1, L5 × T3 and L5 × T4 for yield attributes; L4 × T1, L4 × T2, L3 × T1, L7 × T1, L3 × T2, L6 × T3 and L1 × T1 for quality traits; L6 × T1, L7 × T4, L3 × T2, L7 × T1 and L7 × T3 for ChiLCV resistance. Lines vs. testers showed significant differences for all the characters except for plant height. The GCA effects for testers were significant for all the traits except for days to first harvest. The ratio of σ2GCA/σ2SCA was less than unity for all the characters, which indicated the predominance of non-additive gene effects in the inheritance of these traits. The contribution of lines were more compared to testers for all the characters except for primary branches plant-1. The superior lines based on GCA effects were L1, L3, L7 and L6 for yield attributes; L2, L3, L4 and L7 for quality traits and L1, L2 and L4 for ChiLCV resistance. Among testers, T1 and T2 were best general combiners for yield and quality traits, and T1 and T3 for ChiLCV resistance. The hybrids viz., L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2, L5 × T3, L5 × T4, L7 × T3 were most promising with desirable SCA effects, heterosis and per se performance for yield and quality attributes and they were moderately resistant to ChiLCV except L5 × T3 and L5 × T4. The hybrid L1 × T1 and L7 × T1 had both parents with high GCA effects for yield plant-1. All the four testers were symptomless and among seven lines, two were moderately resistant and five were moderately susceptible. Among 28 F1 hybrids, 12 showed moderate resistant reaction, 11 were moderately susceptible and five susceptible. The check hybrids CH-27 and Arka Harita were moderately resistant and susceptible respectively. Three superior crosses identified from line (L) × tester (T) analysis viz., cross 1 (L1 × T1), cross 2 (L3 × T2) and cross 3 (L7 × T1) were utilized for generation mean analysis. The six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were developed and evaluated during 2018 summer. Both simple and joint scaling tests were significant for all the characters in all the crosses indicating the inadequacy of additive-dominance model and involvement of digenic or higher order non-allelic gene interactions. Duplicate type of epistasis was observed for plant height, days to first flower, days to first harvest, fruit length, fruit girth, vitamin C, carotenoids and ChiLCV resistance (cross 1); plant height, primary branches plant-1, days to first harvest, fruit girth, fruit weight, fruits plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 2); primary branches plant-1, days to first flower, days to first harvest, fruit girth, fruit weight, fruits plant-1, yield plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 3). These crosses can be improved by biparental mating between recombinants in early segregating generation and delaying the selection in the advanced generations. Complementary type of epistasis was noticed for fruits plant-1, yield plant-1 and yield plot-1 (cross 1); fruit length, yield plant-1 and yield plot-1 (cross 2); plant height and yield plot-1 (cross 3). Additive, additive × additive or complementary gene interactions are fixable, thus, these crosses can be exploited effectively through pedigree method of selection. For ChiLCV resistance dominance (h) gene action, additive × additive (i), additive × dominance (j) and dominance × dominance (l) type of gene interactions are significant. Among them, the former three are in negative desirable direction. The four ChiLCV resistant genotypes identified in this study could be used as potential parents for ChiLCV resistance breeding programme. The 93 per cent similarity of the amplified sequence to ToLCKV suggests that, it could be a strain of ToLCKV responsible for ChiLCV disease. The parents L1, L3, T1 and T3 were superior on the basis of GCA effects for most of the economic traits studied. The hybrids L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2 and L7 × T3 were most promising for yield and quality traits, and were moderately resistant to ChiLCV. The dominance (h) gene action and dominance × dominance (l) epistasis were predominant for yield and quality traits indicating the importance of heterosis breeding in varietal improvement of chilli. The ChiLCV resistance could be improved through recombinant breeding or recurrent selection.
Open Access
Aggrading lateric soils (ultisol) using biochar
(Department of Soil Science, College of Horticulture, Vellanikkara, 2019) Rajakumar, R; KAU; Jayasree Sankar, S
The present investigation was undertaken at College of Horticulture, Vellanikkara and Agricultural Research Station, Mannuthy during 2016-2018. The study consisted of production and characterization of bioehar from coconut based materials, an incubation experiment, and two field experiments. The incubation experiment was conducted for 15 months to study the dynamics of C and N in soil over time and the soil samples were analyzed for C and N fractions at three months' interval. Two field experiments were carried out sequentially, wherein Chinese potato was raised to study the direct effect of bioehar and vegetable cowpea was the test crop to study the residual effect of bioehar applied to the first crop. Three levels of bioehar (5, 7.5, 10 t ha"'), FYM 10 t ha"', soil test based POP + bioehar 10 t ha"' and soil test based POP were the treatments, for both incubation and field experiments. Soil test based POP consisted of NPK and FYM 10 t ha"'. Control plots without the addition of biochar/fertilizers were also maintained. Recovery of bioehar from coconut husk and shell (1:1) on pyrolysis was 22 per cent. The produced bioehar had an alkaline pH (10.01), high EC (3.42 dS m"'), C (64.14 %), CEC (15.78 cmol (+) kg"'), and C: N ratio (113:1). Total N, P, K, Ca, Mg and S contents were 0.567, 0.982, 4.175, 1.19, 0.456 and 0.244 per cent, respectively. Regarding physical properties, bioehar had low bulk density (0.128 Mg m"^), very high porosity (84.63 %) and WHC (307.3 %). Basicity and acidity of bioehar were 2.02 and 0.08 mmol g"', respectively. The surface morphology and chemistry studied using SEM, TEM, FT-IR and Raman spectroscopy revealed the porous, aromatic and recalcitrant nature of bioehar and the presence of functional groups mainly carboxyl, hydroxyl and carbonyl. Results of incubation experiment revealed that the content of organic carbon - (OC), water soluble carbon (WSC) and microbial biomass carbon (MBC) increased up to 6 months of incubation and decreased thereafter. In the case of permanganate oxidizable carbon (POXC) and hot water soluble carbon (HWSC), a decreasing trend was noticed. While the highest value of WSC and HWSC were recorded in FYM 101 ha"', all other C fractions were higher in the treatments viz. soil test based POP + bioehar 10 t ha"' and bioehar 10 t ha"'. With an increase in levels of bioehar, the labile C fractions viz. POXC and MBC increased. The labile C fractions in soil were in the order POXC > HWSC > MBC = WSC. As regards the N fractions, NH4-N declined steadily at 3 months, then increased up to 9 months of incubation after which it decreased till the incubation ended. The NO3-N and amino acid N increased up to 12 months of incubation and slightly declined thereafter. Increase in total hydrolysable N was noticed up to 6 months of incubation and thereafter, a progressive decrease was noticed. While the total N content decreased over the incubation period, the KMn04-N increased. With an increase in levels of biochar, the NO3-N and KMn04-N increased. The treatments soil test based POP + biochar and soil test based POP were equally superior to other treatments with respect to N fractions. Results of field experiments revealed the superiority of biochar 10 t ha"' in increasing soil pH and NH4OAC-K and reducing the exchangeable acidity. The treatments soil test based POP + biochar and soil test based POP were superior with respect to most of the soil properties. Application of biochar at 10 t ha"', either alone or in combination with POP improved the soil properties viz. OC, dehydrogenase activity, CEC, MWHC and hot water soluble B. With an increase in levels of biochar, the soil properties viz. pH, CEC, WHC, dehydrogenase activity, NH4OACK, Ca, HCl-Zn and humic acid increased. With respect to the growth parameters and yield of Chinese potato, application of soil test based POP + biochar and soil test based POP were comparable. The same treatment soil test based POP + biochar that faired in terms of direct effect proved good in residual effect as well, as reflected from the plant growth and yield of cowpea. Path analysis had shown that the soil properties viz. OC, MBC, Bray-P, NH4OAC-K, Ca and EC directly influenced the tuber yield, reinstating the role of biochar in yield improvement. The nutrient content in plant parts and its uptake varied among treatments and corroborated the trend. Considering the quality attributes of Chinese potato, the treatments biochar 10 t ha"' and soil test based POP + biochar recorded higher CHO content. Protein content was highest in the treatments soil test based POP and soil test based POP + biochar. The advantage of biochar on increasing protein content and decreasing crude fibre content was visible in the succeeding crop of cowpea also, thus establishing its high residual effect. The study revealed the potential of biochar as an amendment in the highly weathered, nutrient-poor acidic laterite soils of the tropics. Its application brought about increase in soil pH, addition of basic cations, improvement in CEC and WHC, and gradual release of nutrients to the growing plants. The overall improvement in physical, chemical and biological soil conditions through biochar could promote plant growth, yield as well as quality. The positive effect of biochar could be observed in combination with soil test based fertilizer application also.

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