Browsing by Author "George Thomas, C"

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Comparative biology and growth behaviour of Pennisetum polystachyon (L.) Shult and P. pedicellatum Trin
(Department of Agronomy, College of Horticulture, Vellanikkara, 2000) Karthik, A; George Thomas, C
Pennisetum polystachyon (L.) Shult. and P. pedicellatum Trin. are two major grass weeds that are widespread in young plantation crops and non-arable areas of the tropics. The present investigation was undertaken to have an understanding on the biology, growth behaviour and fodder production potential of these two Pennisetum spp. at the Research Farm, College of Horticulture, Vellanikkara during 1998-2000. Germination tests were conducted at monthly intervals. P. polystachyon did not show any dormancy and started germination as soon as the seeds are collected (December). P. pedicellatum seeds remained dormant during December and January and it started germination by February only. Both species showed above 80 per cent germination by late March. Germination percentage started to decline in P. polystachyon after April. Phenological characters of both species were noted from a natural population during the year 1999. Seeds of Pennisetum spp. started germination soon after the receipt of monsoon showers by the end of April. Flowering started after the completion of the rainy period in September. Plants started senescence by mid December in P. polystachyon and mid November in P. pedicellatum. Both Pennisetum species studied showed remarkable regeneration ability from different cutting heights. The percentage of plants regenerated was similar in both species, Allelopathic reactions of roots, leaves and seeds were also studied. Boiled and unboiled extracts were prepared and germination test were conducted using cowpea, bhindi and cucumber as test crops. The cold and boiled leaf extracts of both species did not show any effect on germination of test crops. However, cold root extract of both Pennisetum spp. reduced the germination percentge of bhindi. Cold root extract of both species also showed some promotery effect on shoot length in cowpea. Seed extracts showed inhibitory effects only on cowpea germination. Growth was comparatively fast in P: pedicellatum than P. polystachyon during its early stages. P. polystachyon showed higher leaf : stem ratio than P. pedicellatum. Growth indices like LAR, LWR, RGR, AGR and NAR were similar in both Pennisetum spp. In terms of total green fodder production, P. pedicellatum was superior to P. polystachyon. Two cuttings, one at 70 days after sowing and the other just before flowering recorded maximum fresh weight of fodder. Though crude protein content was similar in both the species, P. pedicellatum showed a higher crude fibre content than P. polystachyon. The results indicate that as the fodder quality is good, utilizing these grasses as cattle feed can be one of the strategies for managing them. However, cultivation of these grasses for fodder purposes involves some risks because of their high reproductive capacity and persistence.
Comparative biology and growth behaviour of Pennisetum polystachyon(L.) Shult. and P. pedicellatum Trin.
(Department of Agronomy, College of Horticulture, Vellanikkara, 2000) Karthik, A; George Thomas, C
Pennisetum polystachyon (L.) Shult. and P. pedicellatum Trin. are two major grass weeds that are widespread in young plantation crops and non-arable areas of the tropics. The present investigation was undertaken to have an understanding on the biology, growth behaviour and fodder production potential of these two Pennisetum spp. at the Research F~ College of Horticulture, Vellanikkara during 1998-2000. Germination tests were conducted at monthly intervals. P. polystachyon did not show any dormancy and started germination as soon as the seeds are collected (December). P. pedicel/alum seeds remained dormant during December and January and it started germination by February only. Both species showed above 80 per cent germination by late March. Germination percentage started to decline in P. polystachyon after April. Phenological characters of both species were noted from a natural population during the year 1999. Seeds of Pennisetum spp. started germination soon after the receipt of monsoon showers by the end of April. Flowering started after the completion of the rainy period in September. Plants started senescence by mid December in P. polystachyon and mid November in P. pedicellatum. Both Pennisetum species studied showed remarkable regeneration ability from different cutting heights. The percentage of plants regenerated was similar in both species. Allelopathic reactions of roots, leaves and seeds were also studied. Boiled and unboiled extracts were prepared and germination test were conducted using cowpea, bhindi and cucumber as test crops. The cold and boiled leaf extracts of both species did not show any effect on germination of test crops. However, cold root extract of both Pennisetum spp. reduced the germination percentge ofbhindi. Cold root extract of both species also showed some promotery effect on shoot length in cowpea. Seed extracts showed inhibitory effects only on cowpea germination. Growth was comparatively fast in P. pedicellatum than P. po/ystachyon during its early stages. P. polystachyon showed higher leaf : stem ratio than P. pedicellatum. Growth indices like LAR, LWR, RGR, AGR and NAR were similar in both Pennisetum spp. In terms of total green fodder production, P. pedicellatum was superior to P. polystachyon. Two cuttings, one at 70 days after sowing and the other just before flowering recorded maximum fresh weight of fodder. Though crude protein content was similar in both the species, P. pedicellatum showed a higher crude fibre content than P. polystachyon. The results indicate that as the fodder quality is good, utilizing these grasses as cattle feed can be one of the strategies for managing them. However, cultivation of these grasses for fodder purposes involves some risks because of their high reproductive capacity and persistence.
Ecofriendly management of weeds in rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 2008) Sindhu, P V; George Thomas, C
Competition from weeds and consequent yield reduction is a major problem in rice cultivation, which warrants proper weed management strategies. The present study was undertaken to develop and refine stale seed bed techniques and subsequent cultural practices for semi-dry and wet-seeded rice and to find out the optimum plant spacing, which can give maximum weed control efficiency coupled with better grain yield. Survey and documentation of prevailing weed control practices followed by rice farmers was another objective of the study. Surveys conducted in Palakkad, Kole, Kuttanad and Pokkali regions revealed the popularity of physical and chemical methods of weed control among farmers. Among various herbicides available for use in rice, Fernoxone (2,4-D) is the major chemical used by the majority of farmers of Palakkad, Kole and Kuttanad regions. The experiment on stale seed bed techniques for semi-dry rice was conducted during first crop seasons of 2006 and 2007 at Agricultural Research Station, Mannuthy and stale seed bed for wet-seeded rice was conducted in Alappad kole, Thrissur district during second crop seasons of 2005-06 and 2006-07. Seed bed preparation significantly influenced the germination and establishment of weeds both under semi-dry and wet-seeded conditions. Population and dry weight of weeds were the lowest in stale seed bed for 14 days. Stale seed bed technique adopted for forcing the germination of weed seeds showed differential response by different groups of weeds. Grass weeds gave the highest germination percentage immediately after seed bed preparation followed by broad leaf weeds. However, seed bed preparation was not effective on sedges. Stale seed bed technique provided a partially weed free environment during the early crop growth stages and allowed the crop to yield better than normal seed bed. The yield difference between normal seed bed and stale seed bed decreased with reduction in the stale seed bed period mainly because of the short time available to achieve the optimum environment essential for the germination of buried seeds. Among the sub plot treatments, pre emergence spraying of herbicides and concurrent growing of green manure crops gave significant reduction in the population and dry weight of weeds and thus better grain yield. Stale seed bed for 14 days gave the highest benefit ratio both under semi-dry and wet-seeded situation during both years of the experiment. Experiment to assess the influence of plant stand on crop-weed competition was conducted in farmer’s field at Alappad Kole, Thrissur district during the second crop season of 2005-06 and 2006-07. Canopy modification by altering plant spacing significantly helped the crop to maintain a dominant position over weeds as indicated by the decreased weed problems in closer plant spacing. Higher grain yields of 8858 kg ha-1 and 7825 kg ha-1 during first and second years of study were observed in closer spacing of 10 cm X 10 cm spacing under the recommended package of practices of Kerala Agricultural University followed by 20 cm x 10 cm. Among the weeded plots, the lowest grain yield was in SRI plots with cono weeding. Plants at wider spacing (30 cm X 30 cm) produced more number of tillers per hill. However, on unit area basis a reverse trend was observed. Increase in plant density under closer spacing significantly reduced the dry matter production of weeds. The weed problem was very high in SRI management, even after four cono weedings. The reduction in grain yield in unweeded plots under closer plant spacing was negligible when compared to weeded plots. This indicates the possibility of maintaining the field without much economic loss from weeds by transplanting 20-day old seedlings, with two seedlings per hill at a closer spacing of 10 cm X 10 cm. This is both economical and ecofriendly as the need for hand weeding or herbicides is eliminated. The present experiment indicates that SRI system does not hold much promise in regions where farmers follow recommended package of practices.
Emergence and competition of Polla in semi-dry rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 1999) Renu, S; George Thomas, C
Extraction pattern of soil moisture by bittergourd (Momordica charantia L.) under varying irrigation levels
(Kerala Agricultural University, 1990) George Thomas, C; Pillai, G R
Identification of drought tolerant cocoa types
(Department of Agronomy, College of Horticulture, Vellanikkara, 2005) Binimol, B; George Thomas, C
Experiments were conducted at the college of Horticulture, Vellanikkara to investigate the drought tolerant characteristics of the most promising cocoa varieties and accessions. The investigation involved a two-stage screening of cocoa seedlings and budlings and monitoring of their field grown plants. As the first step, a preliminary screening was done on six month old seedlings and budlings of ten cocoa cultivars released from Kerala Agricultural University and twenty promising accessions. A secondary screening of cocoa cultivars/accessions selected from the preliminary screening was then conducted. Simultaneously, field monitoring of cocoa trees of the varieties selected from the primary screening was also done. From the preliminary screening, seven apparently tolerant varieties were selected for secondary screening in both seedlings and budlings based on higher RWC and DWF, lower percentage of dried leaves and longer duration of life under during moisture stress. Three apparently sensitive verities were also selected based on opposite values of the above characters. Varieties identified in the preliminary screening were subjected to a secondary screening under three moisture regimes of no irrigation , watering once in five days (life saving irrigation), and regular watering. Observations on physiological parameters such as relative leaf water content, dry weight fraction, leaf drying percentage, number of days taken for complete drying, stomatal conductance, transpiration rate, leaf water potential, chlorophyll ‘a’, ‘b’ and total chlorophyll, chlorophyll stability index, leaf area per seedling, membrane stability, relative injury; growth characters like plant height, collar girth, number of leaves and total biomass; biochemical characters such as proline content and nitrate reductase activity were recorded. After conducting a cluster analysis, the varieties with high RWC, DWF, total chlorophyll content, leaf water potential and proline content; low stomatal conductance, transpiration rate and leaf area during water stress were rated as drought tolerant and with opposite characters as drought sensitive. Based on these, in seedlings; the varieties M 13.12, GII 19.5 and GVI 55 were ranked as moisture stress tolerant and GVI 61, GV 50 and GI 4.8 as sensitive under no irrigation. In budlings, the varieties GI 4.8 and GII 19.5 were selected as drought tolerant and GIII 4.1, GVI 51 and GII 12.3 as drought sensitive under no irrigation Important characters were also monitored in 16-year old clonal trees of the seedlings/budlings of the varieties selected from primary screening. Transpiration rate, stomatal conductance, leaf water potential, stomatal frequency, leaf thickness, bark thickness and soil moisture content were recorded during summer. The varieties GVI 61, M 13.12 and GI 4.8 showed drought tolerant features. The accession M13.12 (CCRP2) showed drought tolerant features in secondary screening of seedlings and field performance. The accession GVI 51, which showed sensitivity to moisture stress in seedlings (but tolerant in budlings) under secondary screening, was showing similar behavior of sensitivity in field grown plants. The study shows the possibility of exploiting drought tolerant features of cocoa varieties/accessions. However, final conclusions are difficult to be drawn as only 10 accessions were subjected to secondary screening and field monitoring, and data for only one year were collected. In the light of the promising results obtained, screening trails involving more number of varieties/accessions have to be conducted and monitored for more number of years to get consistent values.
Irrigation and tillage practices for fodder maize (Zea mays L) in rice fallows
(Department of Agronomy, College of Horticulture, Vellanikkara, 2013) Subba Reddy, B; George Thomas, C
A field experiment was conducted at the College of Horticulture, Vellanikkara during 2012-13 summer season to study the response of fodder maize (Zea mays L.) to different irrigation practices and tillage methods. The treatments consisted of four levels of irrigation (irrigation at IW/CPE ratios of 0.4, 0.8 and 1.0 and no irrigation) and three tillage methods (herbicide based zero tillage, minimum tillage and conventional tillage). The experiment was laid out in split plot design with three replications. The study revealed that fodder maize responded well to frequent irrigations and herbicide based zero tillage. Biometric characters such as plant height, number of leaves/plant, leaf area, leaf area index and shoot: root ratio were higher in frequently irrigated plots with herbicide based zero tillage whereas leaf: stem ratio was lesser in frequently irrigated plots. Stem dry matter, total dry matter production and fresh forage yield were higher in frequently irrigated, herbicide based zero tillage plots. There was no significant difference between levels of irrigation or tillage methods with respect to per cent content of phosphorus, potassium, calcium and magnesium. However, nitrogen and crude protein contents decreased with increased levels of irrigation. Leaf crude fibre increased with increased levels of irrigation but no differences in stem crude fibre was noticed among treatments. Uptake of nutrients was higher in herbicide based zero tillage plots receiving more number of irrigations. Consumptive use, field water use efficiency and crop water use efficiency were higher in frequently irrigated plots (IW/CPE= 1.0 and 0.7). Frequently irrigated plots extracted more water from the top layers. In general, fodder maize extracted 61-79 per cent of the total water use from the top 30 cm soil layer. Among the irrigation schedules IW/CPE=1.0 recorded the highest gross returns, net returns and B: C ratio followed by IW/CPE=0.7. Among the different tillage methods herbicide based zero tillage resulted in the highest net returns and B: C ratio. It can be concluded that fodder maize cultivation with 40 mm irrigation scheduled at IW/CPE ratio 1.0 with herbicide based zero tillage is superior with respect to fodder yield and net returns, and hence suited for summer rice fallows where water for irrigation is available. Depending on mean daily evaporation values in Kerala, this translates to irrigation with 40 mm water (40 L/m2) at an interval of 6-9 days.
Management and utilization of water hyacinth (Eichhornia crassipes ( Mart.) Solms)
(Department of Agronomy College of Horticulture, Vellanikkara, 2018) Indulekha, V P; George Thomas, C
Performance of different planting materials of tannia (xanthosoma sagittifolium(L.) schott) under shade
(Department of Agronomy, College of Horticulture, Vellanikkara, 2018) Nayana, V R; George Thomas, C
Performance of hybrid napier cultivars under rainfed conditions
(Department of Agronomy, College of Horticulture, Vellanikkara, 2012) Savitha Antony; George Thomas, C
Hybrid napier, an inter-specific cross between bajra (Pennisetum glaucum (L.) R. Br.) and napier (Pennisetum purpureum Schum.) is a popular fodder grass with high nutritive value and herbage yield. Hybrid napier cultivars perform well under irrigated condition but their performance under rainfed condition is not evaluated. A field experiment was conducted at the College of Horticulture, Vellanikkara to evaluate the performance of 11 popular cultivars under rainfed conditions—CO-2, CO-3, CO-4, KKM-1, Suguna, Supriya, IGFRI-3, IGFRI-7, DHN-6, PTH and PBN-16. Slips were planted at a spacing of 60 cm X 60 cm in June, and growth, fodder yield and nutrient uptake were studied at 45 days interval. The first harvest was taken at 75 days after planting and subsequent harvests at 45 days interval. The cultivars differed significantly in various parameters such as plant height, tillers/plant, leaves/plant, leaf width, leaf length, leaf area index, net assimilation rate, relative growth rate, leaf area ratio, leaf: stem ratio and shoot: root ratio. Four harvests were made, the last being in January. Green and dry fodder yield were maximum during the first harvest, thereafter, yield decreased. In summer, no harvesting was done due to stunting and drying of plants. Among the eleven cultivars evaluated, CO-3 recorded the highest green fodder yield followed by DHN-6. Nutritive values and oxalate content showed significant differences among the cultivars. Crude protein content was maximum in CO-3 and IGFRI-3. In general, CO-3 showed supremacy over other cultivars in terms of overall nutritional quality. Oxalate content, an antinutritive factor, was found to be the highest in Suguna. Nutrient uptake was higher in the first harvest, and CO-3 had the highest nutrient removal. In summer, maximum RLWC was noticed in Supriya and CO-3, and the lowest in IGFRI-3. All the clumps of CO-3, CO-4 and PTH survived the dry periods and maximum mortality was noticed in PBN-16 followed by IGFRI-3, DHN-6, CO-2 and KKM-1. The study revealed that CO-3 is superior to all other cultivars with respect to yield, nutritive value and the ability to withstand drought, and hence, CO-3 is highly suited for rainfed cultivation. Since there was no mortality of clumps for CO-4 and PTH, these cultivars can also be considered. Although DHN-6 showed 25 percent mortality of clumps during summer, as it outyielded other cultivars during rainy period, it may be suitable for areas with well distributed rainfall.
Research planning, implementation and reporting
(College of Horticulture,Kerala Agricultural University, 2005) George Thomas, C
Shade tolerance, nitrogen nutrition,and harvest management in hybrid napier under rainfed condition
(Department of Agronomy, College of Horticulture,Vellanikkara, 2016) Savitha Antony; George Thomas, C
Hybrid napier, an inter-specific cross between bajra and napier, is a popular fodder grass because of its high yield potential and quality. Three field trials were conducted during 2013–2015 with the objectives of assessing shade tolerance of selected hybrid napier cultivars, finding out optimum nitrogen levels and harvesting frequency, and studying the influence of different cutting heights on regrowth and mortality of major cultivars under rainfed condition. The performance of six cultivars of hybrid napier(CO-3, CO-4, Suguna, IGFRI-3, DHN-6 and PTH) at three different shade levels (0 per cent, 25 per cent and 50 per cent) were studied under rainfed condition. Increasing shade levels had a facilitating effect on plant height, leaf length, leaf width, leaf area index, leaf area ratio, leaf weight ratio, leaf- stem ratio, chlorophyll content and PAR interception, whereas, number of tillers, number of leaves, specific leaf weight, and fodder yield were reduced under shade. ‘Suguna’ had the highest fodder yield followed by ‘CO-3’ and ‘CO-4’. Shade also affected the nutritive value and quality of leaves and stems. Oxalate content in plants increased with increasing shade and ‘IGFRI-3’ had the highest content. The effect of nitrogen levels (0, 100, 200, 300, and 400 kg/ha) and three cutting intervals (30, 45, and 60 days) were tested on hybrid napier cultivar ‘CO-3’. Cutting frequency and nitrogen affected plant growth, yield, and yield attributes. Delayed harvesting reduced fodder quality. Crude protein, crude fat, Ca, Mg, oxalate, and nitrate contents increased with increasing nitrogen levels while total ash, K and P contents remained unaffected. The nitrogen use efficiency (NUE) decreased with increasing cutting intervals and nitrogen doses. The highest NUE was recorded at 45 days cutting interval and with 200 kg/ha N. Soil organic carbon content increased after the experiment but available N, P, and K declined. The experiment to study the effect of different cutting heights (5, 10, 15, and 20 cm) on regrowth and mortality of major cultivars (CO-3. CO-4, Suguna, DHN-6 and PTH) revealed that cutting height management affected yield attributing factors such as tiller and leaf production and fodder yield. The fodder yield increased with increasing cutting height. Hybrid napier showed maximum regrowth rate when harvested at 20 cm height and showed a declining trend when harvested at lower cutting heights. The cultivars ‘CO-3’, ‘CO-4’ and ‘Suguna’ had comparable regrowth rate. The results from the present investigation have implications for Kerala where land and water are scarce resources for fodder production. As ‘Suguna’ and ‘CO-3’ performed better than other cultivars under shade, these two can be grown where the intercrops receive at least 50 per cent of the incoming solar radiation. Applying 200 kg/ha nitrogen and cutting at 20 cm height at 45-60 days interval seem to be satisfactory for hybrid napier under rainfed condition.
Water management practices for bittergourd (Momordica charantia L.) under different fertility levels
(Department of Agronomy, College of Agriculture, Vellayani, 1984) George Thomas, C; Raveendranathan Pillai, G
Weed flora and their relative dominance in semi-dry rice culture
(Kerala Agricultural University, 1997) George Thomas, C; Abraham, C T; Sreedevi, P
Weed management in cocoa nursery
(Department of Agronomy, College of Horticulture, Vellanikkara, 2001) Shylaja, P, V; George Thomas, C
Experiments were conducted during 2000-2001 at the College of Horticulture, Kerala Agricultural University, Thrissur with the objective of suggesting appropriate weed management strategies involving solarization, fumigation, biofertilizers and herbicides for cocoa nursery. The investigation consisted of two experiments. In the first experiment, solarization at different intervals (15, 30 and 45 day) and fumigation were compared together with biofertilizers (Azospirillum, V AM, Azospirillum + V AM). Seven pre-emergence herbicides were screened in the second experiment along with weed free and untreated control. The major weeds of the nursery area were broad leaf weeds. Solarization for 30 and 45 days and fumigation were very effective in controlling weed growth and biomass of weeds. The temperature at 5 cm depth was 7-9.5°C more than the non-solarized soil. Solarization for 30 and 45 days and fumigation reduced the population of fungi, bacteria and actinomycetes considerably. Increases in the availability of some nutrients - available P, exchangeable K, Ca and Mg - were also observed as a result of solarization for 30 and 45 days. Organic carbon, total nitrogen, ammoniacal nitrogen, nitrate nitrogen were unaffected. Biofertilizers seems to have no appreciable effect on weed population and growth. Solarization for 30 and 45 days and fumigation increased the growth of cocoa seedlings. Increased growth of seedlings resulted in early selection of seedlings for budding from this treatments. Biofertilizers also had significant influences on growth parameters of cocoa and earliness in attaining collar girth of buddable size. Certain growth characters showed interaction effects between solarization and biofertilizers. Solarization for 45 days and Azospirillum + V AM was found to be a superior combination influencing collar girth at all the stages. Among the pre-emergence herbicides tried, diuron (2.0 kg ha"), oxyfluorfen (0.3 kg ha") and pendimethalin (1.5 kg ha") were the most effective in weed control. Atrazine (2.0 kg ha"), oxyfluorfen and pendimethalin had effect ori better growth of seedlings. The maximum number of recovery of stock seedling was from oxfluorfen applied plots; and it also had least effect on soil microorganisms. Alachlor (2.0 kg ha") and metolachlor (1.5 kg ha") were the worst in terms of reduction in microbial population.
Weed management in elephant foot yam[amorphophallus paeoniifolius (dennst.)nicholson]
(Department of Agronomy, College of Horticulture, Vellanikkara, 2017) Lekshmi Sekhar; George Thomas, C