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Open Access
Optimization of shade, nutrients and growth regulators for cut-flower production in anthurium
(Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 1997) Salvy, B R; KAU; Valsalakumari, P K
Experiments were conducted at the Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, during 1995-1997 to optimize the shade, nutrients and growth regulators for cut flower production in Anthurium andreanum var. 'Hawaiian Red'. The effects of three growth regulators, viz., GA, BA and Ethephon with two concentration each, 750 ppm and 1500 ppm, in combination with four nutrients, viz., 1 % fertilizer complex, Hoagland solution, Knop's solution and Ohio solution, were assessed at four levels of shade, viz., 80, 70, 60 and 50 per cent. Post harvest studies were also carried out with an objective to prolong the longevity of cut blooms, following different stage of harvest and giving different pulsing and hold- ing treatments. Results revealed that the different levels of shade and growth regulators significantly influenced all the morphological characters of the plant, viz., height, spread, number of leaves, leaf area, petiole length, number of branches and suckers. Plant height was significantly superior under 80 per cent shade (5.68 cm), 1 per cent fertilizer complex sprays (5.46 cm) and BA 750 ppm sprays (6.11 cm), were superior individually. The superior treatment combination was 70 per cent shade + Knop's solution + 750 ppm BA (7.60 cm). The maximum plant spread (EW - 20.13 cm and NS - 19.80 cm) was under 80 per cent shade. Eighty per cent shade + Ohio solution + 1500 ppm BA recorded the maximum EW spread (26 cm), while NS spread was maximum (28.70 cm) in the treatment combination involving 80 per cent shade + 1 per cent fertilizer complex + 750 ppm BA. The best values of growth parameters were recorded under 80 per cent shade and 750 ppm BA, viz., 14.03 and 14.02, respectively, for number of leaves (9.29 and 10.79 cm, respectively) for petiole length, leaf length (7.76 and 8.33 cm, respectively), leaf breadth (5.93 cm and 6.49 cm, respectively), index leaf area (50.75 cm- and 59.60 cm-, respectively). Total leaf area (423.25 cm? and 517.56 cm>, respectively) and LAI (0.43 and 0.51, respectively) were maximum under 70 per cent shade and BA 750 ppm. The superior combinations for these parameters were 80 per cent shade + Ohio solution + 750 ppm BA, for highest number of leaves (26.20); 80 per cent shade + Ohio solution + 1500 ppm BA for highest petiole length (14.00 cm); 60 per cent shade + Hoagland solution + 750 ppm BA for maximum leaf length (10.50 cm) and 60 per cent shade + 1 per cent fertilizer complex + 750 ppm BA for maximum leaf breadth (8.0 cm). The treatment combination involving 70 per cent shade + 1500 ppm BA with Hoagland solution was the best for maximum index leaf area (90.90 cm-) while same with 1 per cent fertilizer complex was the best for total leaf area (872.00 cm-) and LAl (0.89). Branching started only after 6 months from the commencement of the experiment. It was one month earlier under 80 per cent and 70 per cent shade levels. Significantly superior branching was observed under 80 per cent shade (2.29), fertilizer complex (2.13) and GA 750 ppm (2.37), individually. Treatment combination involving 80 per cent shade + 1 per cent fertilizer complex + 1500 ppm GA recorded the maximum branching (3.80). .' . Sucker production was the best under 80 per cent shade (1.35) and 750 ppm BA (1.35). Treatment combination involving 80 per cent shade + Ohio solution + 750 ppm BA produced the maximum number of suckers (2.5) per plant. Growth behaviour with respect to height, number of leaves, leaf area, number of suckers and branches showed a linear trend. The linear growth rate was consistent and positive under the treatment combination of 80 per cent shade + Ohio solution + 750 ppm BA. Dry matter production was significantly superior under higher shade intensity and lower concentration of BA. The dry weight ratio of shoot:root was the highest (2.15) under the treatment combination of 80 per cent shade + Knop's solu- tion + 750 ppm Ethephon. Leaf longevity was significantly highest (161 days) in the treatment combination, 70 per cent shade + 1 per cent fertilizer complex + 750 ppm BA. Stomatal distribution and size were not influenced significantly by the treatments. Leaf senescence, though was influenced significantly, no particular trend was observed. The aerial root production decreased significantly with decrease in shade intensity. Primary and secondary roots and root spread were the highest under 80 per cent shade and BA 1500 ppm. Maximum root length was observed under 60 per cent shade. Flowering with small stalkless flowers was first observed under 50 per cent shade with GA 750 ppm, at the age of 8 months. Inflorescence with normal size were produced at the age of 13 months, first under 80 per cent shade followed by 70 per cent, 60 per cent and 50 per cent. The time taken for various stages of flower development and the number of inflorescence produced per plant were not influenced significantly. Chlorophyll content in leaf was significantly influenced by shade levels. There was a decrease in chlorophyll content with decrease in intensity of shade. Eighty per cent shade and 1500 ppm Ethephon was superior with respect to the content of green pigments. The highest total chlorophyll content was observed in the treatment combination involving 60 per cent shade + Ohio solution + 750 ppm Ethephon (8.8 mg g -1 fresh weight). Anthocyanin content was not influenced by any of the treatments or combinations. The leaf nutrient content and uptake of nutrients was maximum under 80 per cent shade and BA 750 ppm, individually. Post harvest studies showed that the right stage of harvest of inflorescence was when 1/3 flowers were open on the spadix. Inflorescence harvested at this stage with medium to large size spathe lasted for a longer period (23.33 days). Among the pulsing treatments, BA 50 ppm for 12 hrs, recorded maximum vase life (20.00 days). Among the different holding solutions tried, 8-HQ 30 ppm, BA 20 ppm and Triadimefon 30 ppm recorded the optimum values of PL W, uptake of vase solution, change in pH and EC, and recorded late spathe blueing, late spadix necrosis and high gloss retention. Highest vase life period (27.00 days) was recorded in 8-HQ 30 ppm (25.00 days) and Triadimefon 30 ppm (25.00 days). Among the combinations tried, BA 20 ppm + Bavistin 0.1 per cent showed longest vase life (23.67 days). Maximum net profit per pot (Rs.204.60) was recorded by the treatment combination involving 80 per cent shade + Ohio solution + 750 ppm BA.
Open Access
Performance of selected orchids under varying light regimes, culture methods and nutrition
(Department of Horticulture, College of Agriculture, Vellayani, 1996) Sabina George, Thekkayam; KAU; Mohanakumaran, N
The present study was undertaken to evolve agrotechniques for cut flower orchid production in Kerala. Two experiments were conducted at the College of Agriculture, Vellayani in 1991 and 1992 with two popular cut flower varieties namely Arachnis Maggie Oei ‘Red Ribbon’ and Dendrobium Sonia – 16. The effects of varying light intensities and nutrient regimes under two methods of cultivation were assessed in Arachnis Maggie Oei ‘Red Ribbon’ (Experiment 1) and in Dendrobium Sonia -16, the performance under varying light intensities and nutrient regimes was evaluated (Experiment 2) In Arachnis Maggie Oei ‘Red Ribbon’, trench culture was found to promote growth, flowering and the floral attributes. The number of leaves, aerial roots, leaf area and plant height were greater in the trench grown plants. The number of inflorescences produced, their branching, length and vase life were also enhanced under trench culture. The effect of light intensities on growth was mediated through interactions with culture methods and nutrients. The trench grown plants under 50 and 75 percent light had a greater number of leaves and leaf area. The plants receiving 500 ppm of P and K under 100 percent light had a shorter stature. The direct effect and interactions of nutrients on growth were observed at certain months during the experimental period which was indicative of differences in the requirement at different stages of growth. The dry matter content of the stem and apical shoot was greater in the plants receiving 500 ppm P. Inflorescence production and the vase life of inflorescences was greater under 100 and 75 percent light. Branching of inflorescences was greater under 75 percent light. In Dendrobium Sonia -16 the number of inflorescences produced was greatest under 75 percent light. The length of the inflorescences was greater under 75 percent light and the span area of the flowers was greater under 50 and 75 percent light. Nitrogen at 500 ppm increased the length of the inflorescences, the number of flowers in an inflorescence, and the span area of the flowers. The number of inflorescences produced was also greater in the plants receiving 400 or 500 ppm N, 400 or 500 ppm K and in those receiving 500 ppm P. Interactions between the nutrients and between light intensities and the nutrients were also observed. The nutrient composition of the leaves in both the cultivars were enhanced by the 400 and 500 ppm doses of N and P and 500ppm K. Based on the observed effects, in Arachnis Maggie Oei ‘Red Ribbon’, trench culture of plants under 75 to 100 percent light and a nutrient dosage of 300 ppm N, 400 ppm P and 300 ppm K from planting till nine MAP and thereafter a dosage of 400 to 500 ppm N, 400ppm, P and 500 ppm K can be recommended. In Dendrobium Sonia -16 growing in pots under 75 percent light with 400 to 500 ppm of N, P and K can be recommended
Open Access
Somaclonal variation in black pepper (piper nigrum L)
(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1996) Shylaja, M R; KAU; Sreekandan Nair, G
Investigations on the exploitation of somaclonal variation for screening for resistance to Phytophthora foot rot disease in black pepper were carried out at the Plant Tissue Culture Laboratory of the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during September 1991 to January 1995. Calliclones of different black pepper cultivars viz. Kalluvally, Cheriakanyakkadan, Balankotta, Karimunda and Panniyur – 1 were produced with and without applying in vitro selection pressure using toxic metabolite(s) of Phytophthora capsici. In vitro induction of mutation using gamma irradiation and partial purification of the toxic metabolite(s) present in the culture filtrate of P. capsici were also attempted in the present study. Leaf puncture bioassay of the concentrated culture filtrate (CCF) of P. capsici showed that toxic metabolite(s) were accumulated in the culture filtrate. The symptoms produced by CCF were quite typical of natural and artificial infection by P. capsici. Concentrated culture filtrate induced quick electrolyte leakage from leaves and calluses. Concentrated culture filtrate induced necrosis on susceptible calli. The cultivars showed significant variation in callus necrosis. Prolonged duration of selection/screening with CCF totally inhibited the regeneration potential of the calli. Concentrated culture filtrate was not found to inhibit shoot proliferation and shoot growth in already regenerated cultures but inhibited the root growth. In the three direct selection/screening methods tried for calli viz. growing in CCF incorporated MS medium (Method 1) shaking in CCF incorporated liquid MS medium (Method 2) and double layer culture technique (Method 3), cultivars showed significant differences in callus necrosis and callus growth. Direct screening of calli was not found to inhibit the regeneration of shoots, shoot proliferation and recovery of rootable shoots but affected the root growth adversely. Gamma irradiation of calli using 60Co source did not give any better response to in vitro screening. The toxic metabolite(s) present in the culture filtrate could not be separated by organic solvent fractionation. However ion exchangers like Dowex 1 and Dowex 50 could be used for separation of the toxic fraction from the filtrate. The response of five different cultivars at various stages of development of cultures when compared, it was found that the cultivars differed significantly in callusing, callus growth, regeneration of shoots, recovery of rootable shoots and root growth. The clones regenerated from screened and unscreened calli were further tested for resistance/ tolerance to P. capsici using different methods of screening viz.natural screening (keeping in infected field), screening by electrolyte leakage method and screening by artificial inoculation of culture disc of P. capsici. None of the regenerated calliclones were found to be resistant to the disease in natural screening. When the tolerance level of the regenerated calliclones was looked into, the performance of the unscreened calli derived clones was found better as compared to the screened calli derived ones. The calliclones of different cultivars differed significantly inthetolerance/susceptibility reaction to the disease. The calliclones of Cheriakanyakkadan recorded greater degree of tolerance to the disease when compared to others. Among the cultivars studied, Kalluvally exhibited high rate of somaclonal variation.
Open Access
Standardisation of in vitro techniques for the rapid clonal propagation of Mango (Mangifera indica L.)
(Department of Horticulture, College of Agriculture, Vellayani, 1996) Sulekha, G R; KAU; Rajmohan, K
Standardization of techniques for the in vitro propagation of mango (Mangifera indica L) varieties was attempted. The studies were carried out at the Plant Tissue Culture Laboratory, Department of Horticulture, College of Agriculture, Vellayani, during 1992-96. Attempts for the in vitro propagation via somatic embryogenesis, somatic organogenesis and enhanced release of auxillary buds were made. Six monoembryonic and six polyembryonic mango varieties were subjected to the initial response studies. Neelum (monoembryonic) and Vellari Manga (polyembryonic) varieties were selected for further detailed studies. Explants like nucellus, embryo mass, segments of leaf and inflorescence were used. The effects of culture medium (basal medium, major and minor nutrients, plant growth substances, casein hydrolysate, sucrose, glutamine, coconut water, activated charcoal, polyvinyl pyrrolidone, sodium butyrate, thidiazuron, polyethylene glycol, sodium chloride, silver nitrate, cobalt chloride and agar), culture conditions (light and temperature) and frequency of subculture on the various stages of somatic embryogenesis were studied. Among the various explants tried, somatic embryogenesis could be induced only from nucellus and embryo mass. In Neelum, somatic embryogenesis could be induced in 66.67 percent cultures of nucellus and 75.00 percent cultures of embryo mass. In vellari manga 83.33 percent cultures of nucellus and 66.67 percent cultures of embryo mass responded. Somatic embryogenesis from nucellus of Neelum could be best induced on half strength MS basal medium supplemented with GA3 5.0mg/l, 2,4-D 2.0mg/l, GA3 5.0mg/l, sucrose 60.0g/l, glutamine 400.0mg/l, coconut water 200.0ml/l, activated charcoal 2.5g/l and agar 5.0g/l. The ideal treatment for inducing somatic embryogenesis from nucellus of Vellari Manga was half strength MS basal medium supplemented with 2, 4-D 2.0 mg/l, GA3 5.0mg/l, sucrose 60.0g/l, glutamine 600.0 mg/l, coconut water 200.0ml/l, activated charcoal 2.5g/l and agar 6.0g/l. Subculturing in medium of the same composition at an interval of five days increased the percentage induction in Neelum (30.0 percent) and five to ten days in Vellari Manga (40.0 percent). The best treatment identified for the initiation of somatic embryoids from nucellus of Neelum was half strength MS basal medium supplemented with 2, 4-D 2.0mg/l, GA3 5.0mg/l, BA 1.0mg/l, sucrose 60.0g/l, glutamine 400.0mg/l, casein hydrolysate 500.0mg/l, coconut water 200.0ml/l, activated charcoal 2.5g/l and agar 5.0g/l. The ideal treatment for the initiation of somaticembryoids from nucellus of Vellari Manga was half strength MS basal medium supplemented with 2, 4-D 0.5mg/l, GA3 5.0mg/l, BA 1.0mg/l, sucrose 60.0g/l, glutamine 400.0 mg/l, case in hydrolysate 600.0 mg/l, coconut water 200.0ml/l, activated charcoal 2.5g/l and agar 5.5g/l. Subculturing at an interval of ten days in Neelum and five to ten days in Vellari Manga was beneficial for the initiation of somatic embryoids. The corresponding percentage of initiation of somatic embryoids was 66.67 in Neelum and 55.56 percent in Vellari Manga. A medium containing B5 major salts and MS minor salts supplemented with abscisic acid 5.0mg/l, sucrose 40.0g/l, casein hydrolysate 100.0mg/l, coconut water 200.0ml/l, polyvinyl pyrrolidone 10.0g/l and agar 4.5g/l was the best for supporting the maturation of the somatic embryoids of Neelum. The best medium for the maturation of the somatic embryoids of Vellari Manga contained B5 major salts, MS minor salts, abscisic acid 4.22mg/l, sucrose 40.0g/l, casein hydrolysate 100.0mg/l coconut water 200.0ml/l, polyvinyl pyrrolidone 10.0g/l and agar 5.0g/l. The size of embryoids was the highest (1.0-1.5cm long) when subcultured at an interval of ten days for Neelum and fifteen days (0.5-1.5cm long) for Vellari Manga. Incubating the cultures in darkness at 26 ± 20C favoured the induction, initiation and maturation of somatic embryoids of both the varieties. Near-normal germination of the somatic embryoids of Neelum was observed when cultured on a medium containing B5 major salts and MS minor salts, BA 0.1 mg/l, sucrose 40.0g/l, sodium chloride 0.5g/l, cobalt chloride 10.0 mg/l, polyvinyl pyrrolidone 10.0g/l and agar 5.5g/l. Near-normal germination of the somatic embryoids of Vellari Manga was observed on a medium containing B5 major salts and MS minor salts, BA 1.0 mg/l, sucrose 50.0g/l, sodium chloride 0.5g/l, cobalt chloride 10.0 mg/l, polyvinyl pyrrolidone 10.0g/l and agar 5.5g/l. A few germinated embryoids were planted out. However, they did not survive. Histological and morphological studies ascertained the status of the somatic embryoids formed. Scanning electron microscope studies depicted the morphological features of the developmental stages of the somatic embryoids. Attempts to standardize in vitro propagation via somatic organogenesis and enhanced release of auxiliary buds were not successful. However, de-diffrentiation could be induced from leaf segment explants of Neelum and Mulgoa.
Open Access
Production dynamics of ginger (zingiber officinale R.) under varying levels of shade, nutrients and triazole
(Department of Horticulture, College of Agriculture, Vellayani, 1999) Ajith Kumar, K; KAU; Jayachandran, B K
The experiments were conducted at the Coconut Research Station, Balaramapuram, during 1996-97 and 1997-98 to study the production dynamics of ginger under varying levels of shade, nutrients and triazole. The specific objectives were to study the production potential of ginger under open and different shade levels, to standardise optimum dose of nutrients and mulch for ginger intercropped in coconut garden and to evaluate the efficacy of triazole in the improvement of yield and other desirable characters. The effect of shade on growth and yield contributing parameters viz., tiller number, leaf number, leaf area, leaf dry weight, root spread, root volume, rhizome spread, rhizome thickness, number of rhizomes, leaf thickness, stomatal frequency, DMP and LAI under 20 and 40 per cent shade levels exhibited significant superiority in pot culture study. In pot culture study: maximum fresh ginger yield of 450.0 and 396.3 g plant" were resulted from plants kept under 20 and 40 per cent shade levels respectively. This was 27.4 and 12.2 per cent higher compared to open- condition. The dry ginger yield of 94.5 and 89.2 g plant" were obtained from plants kept under 20 and 40 per cent shade levels respectively. This was 27.8 and 20.7 per cent higher compared to open condition. However, the dry ginger yield obtained from 60 and 80 per cent shade levels were significantly lower compared to open. The shade levels 20 and 40 per cent gave the highest shoot dry weight of 48.9 and 53.6 g plant" respectively. Volatile oil content showed an increasing trend with increasing levels of shade in pot culture study. Maximum NVEE was recorded under 20 and 40 per cent shade levels. Highest starch content was obtained from 20 per cent shade level. Crude fibre gradually reduced with increase in shade levels. The field trial on nutrient requirement of ginger as intercrop in coconut garden revealed that, NPK application at higher levels increased plant height, tillering, leaf number, leaf area, DMP and chlorophyll content. Physiological parameters like, NAR, CGR and RGR were promoted by higher rates of nitrogen application. The results revealed that, N: P, N : K and P : K ratios of l.5 : 1, l.5 : 1 and 1 : 1 respectively, were ideal to get maximum fresh ginger yield. Application of 150 kg N, 100 kg P20S and 100 kg K20 ha-l gave maximum net profit ofRs. 96605/- and Rs. 99227/- during first and second year respectively. The net profit when the existing recommendation of 75 kg N, 50 kg P20S and 50 kg K20 ha-l was Rs. 54960/- and Rs. 54730/- during first and second year respectively. Hence the study suggests that the existing recommendation (75 kg N, 50 kg P20S and 50 kg K20 ha") has to be doubled (150 kg N, 100 kg P20S and 100 kg K20 ha-l) for increasing the productivity of ginger intercropped in coconut garden. Increased rate of fertilizer application did not influence the quality of the produce. Plant uptake of NPK increased with higher levels of fertilizer application. The field experiment on mulch requirement of ginger intercropped in coconut garden showed that the rhizome yield from plots mulched with 30.0, 22.5 and 1 =r. 0 t ha' were on par. Therefore the mulch requirement of ginger intercropped in coconut garden can be reduced from 30 t ha-l to 15.0 t ha-I Application of triazole did not exhibit any beneficial effect on yield and quality of ginger.
Open Access
Bacterial wilt resistance and yield in brinjal (Solanum melongena L.)
(Department of Olericulture, College of Horticulture, Vellanikkara, 1996) Singh, P K; KAU; Gopalakrishnan, T R
Investigations on “Bacterial wilt resistance and yield in brinjal (Solanummelongena L.)” was undertaken in the Department of Olericulture, College of Horticulture, Vellanikkara during 1993 – ’96. Preliminary evaluation of seventy eight brinjal accessions during Kharif 1994 revealed considerable variation for most of the economic characters. Twenty four accessions/varieties selected based on productivity, resistance to bacterial wilt, crop duration, fruit and plant characters from the preliminary evaluation were subjected to detailed evaluation during March – November, 1995. In the long duration accessions, the non – prickly SM 141 has yielded as high as 6.4 kg/plant with maximum number of fruits (113.5) having maximum weight (128.27 g). Among short duration accessions maximum yield was recorded in white fruited Swetha (3.9 kg/plant). The study revealed the necessity for differential spacing depending on the duration and spread of the plant. In addition to the already available bacterial wilt (Pseudomonas solanacearum) resistant varieties viz., Surya, Swetha, ArkaKeshav, ArkaNidhi, BB 44 some more varieties/accessions viz., Annapurna, Composite 2, TGR, SM 71, SM 116 and SM 141 were found resistant under artificial inoculation. The contents of total phenol and O.D. Phenol was higher in the resistant varieties than the susceptible ones. The anatomical studies revealed well developed secondary xylem with small compact cortical cells in the resistant variety compared to the susceptible variety. The nine F1 hybrids differing in size, shape and colour of fruits were compared with their parents during summer 1996. Two F1 hybrids viz., the long stout and deep purple fruited ArkaKeshav x SM 71 and oval and deep purple fruited Surya x SM 116 had surpassed the standard parent by 337.62 per cent and 290.04 per cent respectively in productivity. Both the hybrids having bacterial wilt resistance, desired plant habit and attractive fruit characters can be progressed further. In general the F1 hybrids had more vigour and tolerated infestation of jassids better than the parents. In Kerala the cultivation of brinjal during summer is limited mainly due to heavy incidence of jassids. In the present study varietal variation was observed for resistance to jassids (Amrascabiguttulabiguttula). The long trichomes with high density contributing to a matting effect on the leaf surface may be responsible for the jassid tolerance in varieties like Pusa Kranti and BB 7. These jassid resistant but wilt susceptible varieties yielded 2417.2 per cent and 186.0 per cent respectively more over the intact plants after grafting onto Solanumtorvum. The present study revealed the scope of cultivating jassid resistant varieties viz., Pusa Kranti and BB 7, though highly susceptible to bacterial wilt during the summer months in the state.
Open Access
Improvement of Anthurium andreanum Lind. in Vitro
(Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 1998) Mini Balachandran; KAU; Ramachandran Nair, S
For refining and establishing micropropagation system for Anthurium andreanum cv. Dragon's Tongue, studies were carried out, to solve many of the problems faced in the micropropagation of the variety, such as, improper foliage development, prolonged period for callus induction and multiplication. Investigations were conducted also to explore alternative explants for micropropagation, induction of somatic embryogenesis and development of artificial seeds, crop improvement through induction of somaclonal variation and radiation breeding in vitro. The study was carried out during 1995-98 at the Plant Tissue Culture Laboratory, Kerala Horticulture Development Programme (R & D), Kerala Agricultural University, Vellanikkara. Surface disinfestation with 70 per cent ethyl alcohol wipe followed by treatment with 0.1 per cent HgCl2 for eight minutes recorded maximum survival (99.74%) of cultures in the case of leaf explants. For spadix explants, ethyl alcohol wipe (70%) + emisan (0.1 %) dip for three minutes followed by HgCI2 (0.1 %) for 10 minutes recorded maximum survival (87.56%) of the cultures. , Among the different explants tried (in vivo and in vitro derived explants) callus induction was maximum in the case of in vivo leaf explants. Callus was initiated (86.50%) within 51 days compared to 90 days reported earlier, when cultured In darkness on to the culture media, Nitsch-white (NW) + kinetin 0.5mgl-1 + 2.4-0 0.3 rngl-1 + sucrose 20 gl-1+ glucose 10 gl-1 + agar 6.0 gl-1. Spadix explants and in vitro derived explants (leaves, nodes, petiole and roots) showed good response to callus induction treatments. Among the in vitro derived explants, root explants recorded the maximum callus multiplication. Callus induction from spadix explants was better (59.85%) in half strength MS basal medium supplemented with 2,4-0 0.3 mgl-1 + kinetin 0.5 mgl-1 +Sucrose 30 gl-1 + agar 6 gl-1. Maximum shoot regeneration (92%) was observed after 46 days in Nitsch media supplemented with BAP 0.5 mgl-1 in the case of leaf callus. In the case of callus derived from spadix explants, half strength MS media supplemented with BAP 2.0 mgl-1 + kinetin 2.0 mgl-1 recorded maximum response (71.42). Multiplication rate (22 per culture vessel) of the shoots and growth and development of the leaves and shoots were better in conical flasks (200ml size). For quicker establishment of the plantlets, mud pots gave the best results (85.33%). Incorporation of vesicular -arbuscular mycorrhizae (VAM) Glomus so., into the potting mix improved the growth of the plantlets ex vitro. Among the explants tried for somatic embryogenesis, in vitro derived leaves (53%) and petiole (18.90%) and immature seeds (8.33%) showed positive response. Induction of somatic embryoids was observed in the media, Nitsch-White (NW) supplemented with 2,4-0 1.5 mgl-1 + kinetin 0.15 mgl-1 + sucrose 20 gl-1 + glucose 10 gl-1 + glutamine 200 mgl-1 + agar 6 gl-1 in explants derived from in vitro leaves and petiole. For immature seeds, response was observed in Nitsch media supplemented with 2,4-02.0 mgl-1 + kinetin 0.3 mgl-1 + sucrose 20 gl-1 + glucose10 gl-1 + glutamine 200 mgl-1. Germination of the somatic embryoids was highest in half strength MS media supplemented with BAP 0.1 mgl-1 + glutamine 200 mgl-1 . Viability of the somatic embryoids was observed to be very low (5-10 days). Encapsulation of somatic embryoids was achieved with calcium chloride at 50 ~M and sodium alginate at 3 per cent level • "j After encapsulation, somatic embryoids can be stored up to 20 days without much loss in capacity for germination (15.50%). Germination per cent of encapsulated somatic embryos was improved (39%) after a low temperature storage (4 0C) for 20 days. Rudimentary leaves were observed in plantlets regenerated from ninth and tenth subculture. The colour of the leaves in such plantlets was observed to be pale green. After transplanting also, the plants exhibited poor leaf growth. In such plants the leaf area remained smaller than other plants. But, chlorophyll development was normal. For radiation breeding using y-rays, the irradiation doses above 150 Gy were found to be lethal to callus as well as for shoot tips. Maximum response in terms of plant height, plant spread and leaf area was recorded at lower dose of 50 Gy. Most significant variation observed in in vitro regenerated plantlets compared to mother plants was the reduction in leaf area of mutants regenerated from explants irradiated with 150 Gy. Height of the plant was also less at higher doses of ƛ-irradiation. The plants obtained from the trial on induction of somaclonal variation and radiation breeding were screened for possible mutants and somacional variants using morphological characters, biochemical markers and cytological technique. Morphological characters were recorded for observing possible variability, at periodical intervals after transplanting. Dwarf mutants were observed at higher doses of y-irradiation. The biochemical studies using isozymes revealed no difference among the plants regenerated from different subcultures and different doses of irradiation. But, difference was observed between the non-irradiated and the irradiated plants for the number of bands produced. Peroxidase isoenzyme was found to be the most stable and was expressed in plants regenerated from different subcultures as well as those from irradiated cultures. Five bands were resolved in the case of plants from the repeated subculturing and two bands were resolved in the case of those regenerated from irradiated cultures. Cytological study showed no alteration in the somatic chromosome number, which remained uniform at 2n=30+2B, in all the plants regenerated from the different subcultures and the irradiated cultures.
Open Access
Breeding for resistance to mosaic viruses in pumpkin (Cusurbita moschata Poir)
(Department of Olericulture, College of Horticulture, Vellanikkara, 1998) Jessy, M Kuriakose; KAU; George, T E
Pumpkin Mosaic Virus (PMV) and Yellow Vein Mosaic Virus (YVMV) are the most devastating diseases of pumpkin in Kerala and the only way to manage this is to use virus resistant varieties. Investigations were carried out at Sugarcane Research Station, Thiruvalla, Kerala Agricultural University to identify source(s) of resistance to PMV and YVMV, to study the genetics and biochemical mechanism of mosaic virus resistance and to identify desirable segregants possessing combined resistance to PMV and YVMV. Six species of Cucurbita (103 genotypes) were used for the study. Only one accession Nigerian Local (NL), introduced from Cornell University possessed high level of resistance to both the virus. The mosaic resistance confirmation studies namely, back inoculation, grafting and multi-environment study clearly established that the reaction in NL can be considered as stable. Neither the inoculated leaves nor the uninoculated subsequent leaves of the susceptible variety Ambili showed symptoms when back inoculated with sap from NL in case of PMV. Through back inoculation, viruses could not be isolated from this genotype thereby proving that the resistance is not symptomless carrier type of tolerance. NL did not develop any disease symptom even after grafting on the YVMV infected symptomatic root stock. The environmental fluctuations also did not influence the resistance expression of NL against both PMV and YVMV. Resistance to PMV was evaluated in five parents and their F1, F2 and backcross generations of four cross combinations namely, Amb x NL, AC x NL and Co1 x NL. On an average 96.25 per cent plants in the F1 showed susceptibility. The gene for susceptibility to PMV had only 95 percent penetrance in PV x NL. Under different genetic background the role of gene modifiers in the disease susceptibility expression of the major gene in AC x NL can not be ruled out. The F2 segregation ratio in all the crosses was in agreement with the Mendelian genetic ratio of 3:1 (susceptible : resistant). The test cross (F1 back crossed to NL) confirmed this with a genetic ratio of 1:1 (resistant : susceptible) in all the four crosses studied. The inheritance studies in six generations of all the four cross combinations clearly revealed that the resistance to PMV in pumpkin is controlled basically by a single recessive gene. The role of gene modifiers affecting the expression of this major gene is to be investigated further. Reaction to YVMV in the six generations i.e., P1, P2, F1, F2, B1 and B2 of the four cross combinations under study revealed that the resistance is controlled by a single dominant gene. In the F1 on an average out of 40 plants only 32 were resistant. Hence the influence of gene modifiers in the resistant expression of this dominant gene for resistance to YVMV in heterozygous conditions can not be ruled out and is to be further analysed. The reciprocal crosses also behaved in a similar fashion. Out of 300 F2 plants in each cross, a mean number of 220 plants were resistant and 80 susceptible, fitting in a 3 : 1 ratio indicating the monogenic dominance of resistance. When F1 was back crossed to the susceptible parent, the segregation of resistance and susceptibility was in equal proportion i.e., out of a mean number of 100 B1 plants inoculated 48 were resistant. This very well fitted into 1 : 1 ratio of resistance : susceptibility. So resistance to YVMV is governed basically by a dominant gene, slightly influenced by gene modifiers. Although NL is a good source of resistance to both the viruses under study, the seed germination was as low as 19 per cent. Through seed coat removal, 62 per cent seed germination (43%increase) was noted in NL. The isozyme pattern of peroxidase and esterase enzymes in susceptible and resistant genotype of pumpkin as well as their F1 hybrids was analysed, before inoculation and after inoculation of both viruses. The resistant and susceptible genotypes showed clear cut differences in their peroxidase profile. The susceptible parents had three bands namely, PRX1, PRX3 and PRX6, while the resistant parent NL expressed only one isoform-PRX1 (0.083) before virus inoculation. The hybrid PV x NL exhibited six bands with three additional bands, PRX2, PRX3 and PRX5. The additional band PRX2 can be attributed to the earliness in growth and development of this hybrid. After inoculation of PMV, the band PRX1 expressed before inoculation was not expressed in both the resistant and susceptible parents as well as in their F1 hybrids. In the resistant parent NL an additional band, PRX5 (Rm value 0.463) was noted. This particular isoform might be responsible for resistance to PMV in NL. After infection of YVMV, the resistant parent as well as the resistant F1 hybrids had the additional band PRX4 (Rm value 0.392). There were six bands of esterase in the susceptible parents and only three in the resistant before virus inoculation. The resistant parent after inoculation of PVM, exhibited three additional bands EST1 (0.368), EST4 (0.632) and EST5 (0.721). Consequent to YVMV infection, the additional band EST 4 (Rm value 0.632) observed in NL was thick and the specific activity of this particular isoform might also be responsible for the resistance mechanism. Consequent to virus infection, the total system of esterase was affected, while peroxidase was comparatively stable. The resistant expression of NL against PMV infection can be attributed to the expression of the additional band PRX5 (0.463) and the resistant mechanism against YVMV in NL as well as in the F1 hybrids can be due to the activity of the isoform PRX4 (0.392). Sequential inoculation with PMV followed by YVMV was carried out in 25 seedlings each in the F1, F2, B1 and B2 generations of the four cross combinations namely, Amb x NL, PV x NL, AC x NL, and Co1 x NL to identify plants with combined resistance to both the viruses. In the F1s, eight plants were identified as resistant to both the viruses i.e., one in Amb x NL, two in PV x NL, three in AC x NL and two in Co1 x NL. In the F2, B1 and B2 populations, there were 17, 9 and 37 seedlings respectively, resistant to both the viruses. All the 71 seedlings possessing combined resistance to PMV and YVMV were further evaluated in the field for their biometric and horticultural characters. The studies in general indicated earliness of F1s compared to F2s, B1s and B2s. On an average, the fruit yield in terms of number and weight of fruits in all the crosses was maximum for the F1 plants. In all the crosses, the plants belonging to the F1, F2, B1 and B2 generations produced fruits with external fruit colour as well as flesh colour of either the female parent or the male parent or with a blend of these two colours. Based on resistance to PMV and YVMV, fruit smoothness, non-incidence of other mosaic viruses and yield of fruits, eight most promising superior segregants from among the four cross combinations were selected for further improvement. They included four in Amb x NL, two from Co1 x NL and one each from PV x NL and AC x NL.
Open Access
Analysis of growth, flowering and quality in koduveli (Plumbago Spp.)
(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1999) Jalaja, S Menon; KAU; Prasannakumari Amma, S
Analysis of growth, flowering and quality in plumbago rosea and plumbago zeylanica were undertaken in the College of Horticulture, Kerala Agricultural University, Thrissur during 1995 to 1998. Study analysed the variation in vegetive, physiological, biochemical, anatomical and reproductive characters of the two medicinally important specied of plumbago. The post harvest storage technique of P.rosea were also studied.

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