Browsing by Author "Ashokan, P K"

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Canopy spread of and light infiltration through cassava (Manihot Esculenta Crantz) canopies
(Kerala Agricultural University, 1986) Ashokan, P K; Lalitha Bai, E K; Vikraman Nair, R
Comparative performance of lesser yam
(Kerala Agricultural University, 1982) Ashokan, P K; Neelakantan Potty, N; Sudhakara, K
Comparative performance of some varieties of greater yam (Dioscorea alata L.)
(Kerala Agricultural University, 1984) Ashokan, P K; Potty, N N; Nambiar, I P S
Early growth and performance of six varieties of pepper in the multistoreyed cropping programme in coconut gardens
(Kerala Agricultural University, 1979) Neelakantan Potty, N; Radhakrishnan, T C; Ashokan, P K
Evaluation of colocasia (Colocasia esculenta, (L) schoot) types in Kerala
(Kerala Agricultural University, 1985) Ashokan, P K; Vikraman Nair, R; Potty, N N
Evaluation of sweet potato varieties in uplands of central Kerala
(Kerala Agricultural University, 1983) Ashokan, P K; Vikraman Nair, R
Influence of host plant on the physiological attributes of field grown sandal (santalum album L.).
(Department of Tree Physiology and Breeding,College of forestry, Vellanikkara, 2011) Delphy Rocha; Ashokan, P K
Effects of host plant, casuarina on the carbon assimilation, water and nutrient absorption in field grown sandalwood was studied at College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur during the year 2009-2011. Radioisotopic study to understand the trans-haustorial translocation from the host to field grown sandalwood tree and anatomical studies of sandalwood haustoria were also taken up during the investigation. The investigations were carried out in a six year old sandal-field, where sandalwood tree with and without host were established as a part of an earlier research project. The experiment was laid out with single tree plants, in RBD with three treatments viz, T1 - Sandalwood tree without host (Casuarina) (Host plant dead naturally within 2 years after establishment of sandal), T2 - Sandalwood tree with host (Casuarina), T3 - Sandalwood tree with host (Casuarina) and the host plant cut and removed at six year stage of growth. The host plant casuarina did not influence the height and diameter (dbh) of the sandalwood tree significantly during its six years growth. Sandalwood trees growing with host showed higher rate of photosynthesis (carbon assimilation) than sandalwood trees growing without host. Sandalwood tree growing without specific host can extend its root for finding a host in its vicinity, and forming haustorial connections, for meeting its water and nutrient requirements. Sandalwood trees grown with host showed higher plant water potential than sandalwood trees grown without host. Plant water potential has decreased significantly after the removal of host plant from the sandalwood pit. It also resulted in leaf wilting and leaf fall in sandalwood tree, indicating the contribution of the host in maintaining higher water potential in sandalwood trees. Sandalwood trees growing with host showed higher leaf N, P and K content. The N, P and K content of the sandalwood tree leaf decreased considerably after the removal of the host plant. The removal of host did not show any significant effect on leaf micronutrient content of sandalwood tree. Sandalwood growing without host also formed haustoria with roots of host plants growing in the adjacent pit. The sandalwood growing with host in the same pit showed higher number of haustoria. Total number of haustoria was higher on the primary root of the host followed by secondary and tertiary roots. Size of the haustorium, the depth of the penetration, the length of the penetration peg and area of coverage of endophyte was higher in the case of secondary root haustoria than in tertiary. Anatomical study of sandalwood haustoria showed that elongated parenchyma cells of the haustorium projected towards the host root xylem, making vascular connection between sandalwood tree root and the host plant root. Radioactive phosphorus (32P) labelling on host plant, casuarina and tracing in sandalwood tree and other hosts revealed that there is inter-translocation of nutrients between sandalwood and host plants, sandalwood and sandalwood, host and host. The data indicated that a network of roots of sandalwood tree and the hosts are formed through haustorial connection resulting in xylem-translocation. Peak count of 32P was obtained on the eighth day of its application. Radiotracer studies on different sandalwood tree-host associations showed that association of sandalwood and cocoa as host was efficient in haustorial translocation of 32P. Labelling of wild grasses growing around sandalwood tree with 32P revealed that, sandalwood also depends on wild grass for meeting its nutrient requirements.
Influence of soil moisture regimes and stage of host introduction on seedling growth of sandal provenances
(Department of Tree Physiology and Breeding, College of Forestry, Vellanikkara, 2004) Vijayakumar J Hiremath; Ashokan, P K
The influence of soil moisture regimes and stage of host introduction on seedling growth of sandal provenances was investigated in a pot culture experiment at the College of Forestry, Kerala Agricultural University, Vellanikkara. Two provenances in the South India, Shimoga (Karnataka) and Marayoor (Kerala) were selected for this study. The results showed that the seedlings of Marayoor provenance were taller and having a higher collar diameter as compared to seedlings of Shimoga provenances. The stage of introduction of host did not have any effect on the growth of sandal seedlings. The seedlings where the host was introduced at the time of planting sandal had comparatively higher total chlorophyll in both the provenances as compared to seedlings where the host was introduced three and six months after planting sandal. Highest Nitrogen and Calcium content was observed in Marayoor provenance when the host was introduced at the time of planting sandal, whereas the P content was higher in both the provenances where the host was introduced at the time of planting sandal. The parameters like seedling height, collar diameter, number of leaves, leaf area, dry matter and chlorophyll content decreased due to water stress. The haustorial connections were found only at 300 days after planting sandal. The seedlings of Marayoor 'provenance recorded lower pre-dawn water potential as compared to seedlings of Shimoga provenance. Introducing host at the time of planting sandal or three months after planting sandal, in Marayoor provenance resulted in higher plant water potential. The leaf diffusive resistance was relatively high in Marayoor provenance when the host was introduced at the time of planting sandal. The leaf diffusive resistance was high in water stressed plants. As the haustorial connections were found only at 300 days after planting sandal, it can be concluded that the host need to be planted only six to nine months after planting sandal. This will avoid the early competition between sandal and host. Fast growing pot host during the early phase of its growth may suppress sandal by competition.
Influence of soil moisture regimes on growth and yield in bush pepper (Piper nigrum L.)
(Department of Agronomy, College of Horticulture, Vellenikkara, 2000) Thankamani, C K; Ashokan, P K
Nodulation behaviour of Acacia mangium wikd.in response to rhizobium inoculation
(Department of Tree Physiology and Breeding, College of Forestry, 1998) Dhaneshkumar, P; Ashokan, P K
An investigation was carried out during April 1996 to December 1997 at the College of Forestry, Kerala Agricultural University, Vellanikkara to study the nodulation characteristics of Acacia mangium Willd. plantation and to isolate and compare the efficiency of rhizobia from different agroclimatic regions of Kerala. The efficiency of these rhizobial isolates under varying conditions of soil fertility and acidity were also evaluated. Survey conducted throughout the state showed rhizobial association and nodulation in all mangium plantations. The soil of these plantations were acidic with pH values ranging from 4.9 to 6.2. Experiments conducted to study the rhizobial characteristics indicated that, the fast growers (Rhizobium spp.) as well as the slow growers tBradyrhizobium spp.) are involved in nodulation of A. mangium in Kerala. The efficiencies of different rhizobial isolates were studied in polypots using sterilized and unsterilized soil - sand mixture. Two other polypot experiments were conducted to study the response of the rhizboial isolates to liming and Nand P application. The experiments were laid out in C.R.D with three replications. Seedlings raised in unsterilized soil performed better as compared to seedlings in sterilized soil. However, the response to inoculation was more prominent in sterilized soil. In sterilized soil, seedlings inoculated with Rhizobium isolates from mangium ;MRh-3 (Mananthavadi), MRh- 2(Perambra), MRh-13 (Trivandrum), MRh-6 (Vellanikkara) and MRh-lO (Mavelikkara) and commercial mangium culture (" Agroforester - Group A") showed superiority in nodulation and growth characteristics while the isolates from A. auriculijonnis and commercial culture of A. auriculijonnis, ("Agroforester - Group C") were not much effective. Seedling - response to inoculation varied with rhizobial isolates, and mangium showed its specificity in Rhiozbium requirement for nitrogen fixation. The application of lime adversely affected nodulation capacity of the rhizobial isolates of mangium from Kerala, indicating the adaptations of these isolates to acidic soils. The nodulation efficiency of commercial culture "Agroforester - Group A" was improved by lime application, indicating that this strain is adapted to soils of higher pH. The nodulation and nitrogen fixing efficiency of the isolates were improved by supplementating fertilized N and P. The need for a starter dose of Nand P for effective nodulation and efficient Ny-fixation in mangium seedlings. MRh-6 (Vellanikkara) performed poorly in unfertilized soil, but showed superiority when applied with N and P fertilizers, indicating the sensitivity of this isolate to site conditions. As the rhizobial isolates from different agroclimatic regions of Kerala responded differently under varying soil pH and doses of Nand P, inoculation of selected strains of rhizobia depending on site conditions may be needed for successful establishment of mangium seedlings.
Parasitic interference of sandal (Santalum album Linn.) on common agricultural crops from the homesteads
(Department of tree physiology and breeding, College of Forestry, Vellanikkara., 1997) Saju Varghese; Ashokan, P K
Experiments were conducted at College of Forestry. Kerala Agricultural University. Vellanikkara. Thrissur during 1995-96 to elucidate the various aspects of parasitisation behaviour of sandal (Santalum album Linn.). Parasitisation behaviour of sandal on selected agricultural crops occurring in the homesteads of Kerala. response of selected sandal-host combinations to manures and fertilizers and uptake and translocation of nutrients and photosynthates by sandal-host associations were the principal aspects investigated. Pot culture experiments involving a number of hosts like coconut, cashew, banana, black pepper, jack, mango, rubber, casuarina, erythrina and redgram were conducted as part of the study. The results indicated that, growth parameters of the sandal seedling like total dry weight and number of haustoria varied significantly depending on the host associated with sandal. Maximum growth of sandal was observed in association with the host - Casuarina equisetifolia. No significant decrease was observed in the growth of any of the hosts consequent to the parasitisation by sandal. Host is the principal factor governing the growth of sandal and fertilizer levels tried in this experiment had not caused any significant influence on the growth of sandal seedlings. In, view of the favourable influences by the host complex of a good and bad host together ie., casuarina + erythrina, on sandal's growth, the possible competitive/complementary effects of multiple host combinations on sandal's growth, need be investigated in greater detail. Sandal plants can take up elements like calcium, sulphur and phosphorus directly from soil and a small fraction of these are also obtained from host. Carbon compounds also are translocated between sandal and hosts. The same host differed in its ability to supply different elements to sandal ie., in the supply of phosphorus to sandal casuarina was better while carbon compounds were optimally supplied by erythrina. So instead of providing a single host to sandal, a variety of good hosts should be provided in the field for ensuring a more optimal growth of sandal. Anatomical studies showed that, sandal roots can establish direct vascular connections with host roots through haustoria.
Performance of multipurpose trees in coconut based agroforestry systems and their influence on soil physico-chemical and biological properties
(Department of Tree Physiology and Breeding,College of Forestry, Vellanikkara, 2006) Srinivasan, K; Ashokan, P K
An experiment was conducted to study the effects of intercropping of three fast growing MPTs viz. Casuarina equisetifolia, Ailanthus triphysa and Leucaena leucocephala in coconut plantations, on soil physico-chemical and biological properties; the field experiment was laid out at the Instructional farm, Kerala Agricultural University, Vellanikkara. The influence of three water harvesting structures viz. simple pits, contour trench and ring trench, which were established in the seedling phase were also compared. The experiment was laid out during 1993 in one year old coconut plantation spaced at 7 x 7m .The MPTs were planted between rows of coconut at a spacing of 2.33 m. The experiment was laid out in Randomised Block Design (RBD), with three replications. The result showed that casuarina recorded maximum height (28.02 m) and girth (GBH of 71.76 cm) and biomass accumulation among different MPTs studied. Ailanthus intercropped systems intercepted about 93 percent available sunlight and control plots (coconut alone) intercepted the least with around 57 percent due to their stand leaf area index of 3.21 and 1.52 respectively. It was observed that MPTs had an adverse effect on the productivity of coconut during later stages of the cropping system. MPTs had tremendously increased the water holding capacity and infiltration rate of the soil. Ailanthus interplanted plots showed better water holding capacity and improved the infiltration capacity of the soil. Resorting to agroforestry practices considerably increased the organic carbon content of the soil. Casuarina interplanted plots showed higher available N, P and K and the surface layer had more concentration of available nutrients. As the soil depth increases the available nutrient concentration was found to decrease. Microbial population viz., bacteria, fungi and actinomycetes were also found to increase due to the influence of MPTs intercropped in coconut plantations. The microbial population viz. bacteria, fungi and actinomycetes was found more in coconut intercropped with casuarina plots. Fungi and bacterial population were found more in the 30-45 cm soil layer but actinomycetes was found more in the surface layers. The percentage of VAM infection on the roots was also seen more in casuarina intercropped in coconut garden.
Performance of nine varieties of turmeric (Curcuma longa L.) in coconut gardens
(Kerala Agricultural University, 1979) Neelakantan Potty, N; Ashokan, P K; Radhakrishnan, T C
Production potential of cassava-based cropping systems
(Department of Agronomy, College of Horticulture, Vellanikkara, 1986) Ashokan, P K; Sreedharan, C
A series of field experiments were conducted during the years 1983-84 and 1984-85 at College of Horticulture, Kerala Agricultural University, Trichur, to evaluate some of the cassava based intercropping systems and to investigate the interspecific interactions. There were three field trials and two micro plot trials. In the first field trial, the treatments were factorial combinations of two planing geometries of cassava viz., paired row and square cluster planting geometries of cassava viz., paired row and square cluster planting and four intercropping practices viz., intercropping with colocasia, elephant foot yam, banana and no intercropping. In the second field trial, there wer 12 treatments derived from the factorial combinations of three geometries of planting (paired row, square cluster and triangular cluster) and four intercropping practices (growing a floor crop of cowpea, groundnut, elephant foot yam and not growing any floor crop) in a cassava + banana intercropping system. In the third field trial, the possibility of growing two crops of groundnut in sequence ( Kharif and cowpea and/or Rabi) and the fertilizer requirements of intercrops were studied. All the three field trials were laid out in randomised Block Design and replicated thrice. In one of the micro-plot trials, 32P absorption by the component species in a cassava + banana + elephant foot yam cassava planted in square cluster was studied. polyculture with In the other micro plot trial 32P absorption by cassava and groundnut under the situations of cassava planted in paired row-ridge, mound and flat bed methods were studied. These two microplot trials were laid out in Completely Randomized Design with three replications. Paired row and square clustered planting of cassava gave similar yields as that of normal method when the plant population was the same. Intercropping cassava in square cluster with elephant foot yam resulted in maximum yield of cassava (20.1 t/ha) and elephant foot yam (10.6 t/ha). Banana and colocasia were also found to be successful as intercrops in cassava planted in paired row or square cluster. Intercropping with elephant foot yam and banana resulted in higher yield of cassava. The intercrops colocasia and elephant foot yam recorded lesser yields than the sole crops whereas in intercrop banana such difference was not observed. The maximum LER of 1.81 was obtained in cassava + banana cropping system. The cassava + elephant foot yam intercropping removed 133, 11, 107, 46, 12 and 18 kg/ha of N, P, K, Ca, Mg and S respectively wheras in the cassava + banana combination the corresponding figures were 227, 14, 236, 70, 16 and 11 kg/ha. From the two year trials, the cassava + banana + elephant foot yam cropping system with cassava planted in square cluster (9070 plants/ha) / triangular cluster (6800 plants/ha) was found to be the most productive and economical cropping system. Elephant foot yam was found to be shade tolerant and the yield reduction in intercropped situation was only marginal. The floor crops of cowpea and groundnut were successful in the first year. The land equivalent ratio in cassava + banana + elephant foot yam intercropping was 1.7 and this cropping system gave a net profit of Rs. 13300 per hectare. The N, P, K, Ca, Mg and S removal in a cassava + banana + elephant foot yam cropping system was found to be 198, 24, 200, 166, 34 and 19 kg/ha respectively. Sequential intercropping in paired row planted cassava was not successful, but growing groundnut and red gram simultaneously in the interspace was found to be successful; groundnut was harvested after four months, red gram after eight months and cassava after nine months. The fertilizer requirements of intercrop cowpea and groundnut were found to be only about 60-90 per cent of the sole crop recommendation and the optimum doses of N, P and K worked out were 6, 18 and 18 kg/ha for cowpea and 4, 30 and 30 kg/ha for groundnut. The main crop of cassava also was benefited by the application of fertilizers to the intercrops. The organic carbon and total nitrogen content of soil were reduced in two or three component intercropping systems by the two year cropping practices. The exchangeable P, K, Ca, Mg and SO 4 increased in situations where legmues alone were intercopped and decreased when banana and a floor crop of cowpea, groundnut or elephant foot yam were intercropped. The micronutrient status of the soil was not remarkably changed by the two season cropping. The intercrop and sole crop systems were not different in their influence on the post crop nutrient status of the soil. The radiophosphorus applied to the root zone of any of the components in the mixed cropping system cassava + banana + elephant foot yam with cassava in square cluster planting was absorbed not only by the treated plants but also by the surrounding species. Banana was the most dominant component in this polyculture. In the cassava + groundnut cropping system, cassava was the most dominant component, accumulating about 90 to 98 per cent of the 32P applied to cassava on mounds/ridges and about 50 percent of that applied to the groundnut root zone in the interspaces. Groundnut root system was small and less active and was able to derive only about 2 to 5 per cent of the 32P applied to cassava mounds. It was also deduced that the root interactions were stronger when all the components of the intercropping systems were a longer duration and it would be mild with legume intercrops of short duration.
Productivity of tuber crops under alley cropping of tropical trees
(Department of Agronomy, College of Horticulture, Vellanikkara, 1988) Bindu, R; Ashokan, P K
An experiment was conducted in the coconut gardens of Agricultural Research Station, Mannuthy during the period from May 1987 to February 1988 to evaluate the productivity of various tuber crops under the alleys of coconut (Cocoa nucifera L)+ eucalyptus (Eucalyptus teraticornis), coconut+subabul (Leucaens leucocephala (Lamk) de Wit, coconut+glyricidia (Glyricidia maculata) and coconut + ailanthus (Ailanthus tryphysa Roxb). The tuber crops raised in the alleys were amorphophallus (Amorphophallus campapulatus (Roxb) B1. ex Decne); Cassava (Manihot esculenta Crantz), colocasia (Colocasia esculenta L) and greater yam (Dioscorea alata L). The experiment was laid out in randomised block design in plots of size 7.5 x 7.5 m and replicated 5 times.
Quality characteristics of five varieties of Dioscorea alata L.
(Kerala Agricultural University, 1981) Ashokan, P K; Neelakantan Potty, N; Hassan, M A
Response of rice to applied sulphur
(Department of Agronomy, College of Horticulture, Vellanikkara, 1989) Sherine George; Ashokan, P K
Experiments were conducted at the Agricultural Research Station, Mannuthy and the Radiotracer Laboratory of the Kerala Agricultural University during the first crop season of 1988 to study the response of rice to applied sulphur and the relative uptake and distribution of soil and fertilizer sulphur. There was a field experiment conducted with four levels of sulphur (0, 20, 40 and 60 kg ha-1) and four sources of sulphur (ammonium sulphate basal dressing, ammonium sulphate-top dressing, ammonium phosphate sulphate and elemental sulphur). The experiment was laid out in RBD in plots of size 4.6 m x 4.5 m and replicated thrice. A pot culture experiment was conducted for studying the uptake and distribution of 35 applied as albelled (MH4) 2 SO 4 at 20, 40 and 60 kg ha-1 levels of sulphur application. The utilization of sulphur applied at planting and that applied at panicle initiation were also studied in this experiment. The results showed that plant height and number of tillers were not significantly influenced by the levels of sulphur, sources of sulphur and their interactions. The leaf area index increased due to the application of sulphur at all the growth stages. The dry matter production increased with sulphur application. The increase in dry matter production due to the application of graded levels of sulphur was found to vary from 4 to 47 per cent.
Response of sandal (Santalum album Linn.) seedlings to shade and mycorrhizal association
(Department of tree physiology and breeding, College of Forestry, Vellanikkara, 2002) Binu N Kamalolbhavan; Ashokan, P K
The occurrence of sandal- Arbuscular Mycorrhizal Fungi (AMF) associations in natural sandal growing forests and the response of sandal seedlings to inoculation with commonly available cultures of AMF, shade levels and nature of hosts were investigated in a pot culture experiment at the College of Forestry, Kerala Agricultural University, Vellanikkara. Two important sandal growing regions in the state, Marayoor (ldukki district) and Wadakancherry (Thrissur district) were selected for this study and a non-sandal growing area in Thrissur district was selected as a control for the soil studies . The result showed that characters like height, number of leaves, leaf area and shoot weight of sandal seedlings increased due to the Arbuscular Mycorrhizal Fungi inoculation and maximum response was observed for seedlings grown in soils inoculated with Glomus mosseae. The characters like collar girth, root weight did not show any significant difference for the mycorrhizal inoculation. It was further observed that the interactions between shade and mycorrhizae were the best under 50 per cent shade level especially for those seedlings inoculated with Glomus mosseae. During the initial seedling phase, high shade (75 per cent) is needed for sandal, but during the later stages of seedling growth, medium shade (50 per cent) resulted in best growth of seedlings. Growth of sandal seedlings with two host species, casuarina and redgram was on par. The relative water content and plant water potential were higher in seedlings inoculated with AMF. The N, P, K content of the shoot of sandal seedlings were maximum for seedlings inoculated with Glomus mosseae. Sandal seedlings collected from natural sandal growmg regions investigated for the presence of sandal-AMF association revealed that the roots of sandal seedlings from Wadakancherry forest showed 33 per cent of colonization, while the seedlings from Marayoor forest showed no colonization. Sandal seedlings grown for four months in the soils collected from these two regions showed superior growth when compared to those seedlings grown in soils from the agricultural lands of Thrissur, but no AMF colonization was observed in the roots of the sandal seedlings .
Response of selected forestry and agroforestry tree seedling to water stress
(Department of Tree Physiology and Breeding, College of Forestry, Vellanikkara, Thrissur, 1996) Rajesh, N; Ashokan, P K
An experiment was conducted at the College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur during the period from 1994 to 1995 with seedlings of Acacia mangium Willd., Ailanthus triphysa (Dennst.) Alston., Pterocarpus marsupium Roxb., Swietenia macrophylla King and Tectona grandis L.F. to study the response of the species to water stress. The results showed that the growth characteristics and Physiological behaviour of all the five species were adversely affected due to water stress. Among the five species studied S. macrophylla was the most sensitive species and did not show much adaptations to tolerate water stress. Eventhough A. mangium showed adaptations like quick closure of stomata, thick cuticle and low chloroplast disintegration when exposed to water stress, growth characteristics were found to be adversely affected due to water stress. So the species has to be tested for its water stress tolerance in a long term experiment. Pterocarpus marsupium was also found to be sensitive to water stress and all the growth characters were adversely affected. However, it showed relatively high net photosynthesis and relative growth rate. Ailanthus triphysa was the least sensitive species to water stress. Considering the relative growth rate and net photosynthesis, A. triphysa and P. marsupium are rated to perform well under dry situations. Among the five species studied T. grandis seedlings showed symptoms of permanent wilting when the water stress was increased from moderate (~ 5 Bar SMT) to severe (~ 10 Bar SMT) levels. Other species did not show permanent wilting even when the plants were not watered for nine days condinuously (S3). Growth characteristics in T. grandis was not much affected due to mild (S1) levels of water stress eventhough the plants wilted and dried under severe water stress (S3).
Scope for using tapioca leaves as fodder
(Kerala Agricultural University, 1978) Ashokan, P K; Sreedharan, C