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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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ThesisItem Open Access Germination and plant growth responses in Ashwagandha (Withania Somnifera (L.) Dunal) and Kiriyathu (Andrographis paniculata (Burm.F.) Nees) to seed pretreatments(Department of Plantation Crops and Spices, College of Agriculture, Vellayani, 2020) Namitha, Nadesh; KAU; Deepa S, NairGermination and plant growth responses in Ashwagandha (Withania somnifera (L.) Dunal) and Kiriyathu (Andrographis paniculata (Burm.f.) Nees) to seed pretreatments. The present investigation entitled “Germination and plant growth responses in Ashwagandha (Withania somnifera (L.) Dunal) and Kiriyathu (Andrographis paniculata (Burm.f.) Nees) to seed pretreatments” was conducted in the Department of Plantation Crops and Spices, College of Agriculture, Vellayani during 2018-2020 with the objective to standardize pretreatment of seeds for enhanced germination and plant growth in W. somnifera and A. paniculata. The seeds of W. somnifera and A. paniculata used for the study were sourced from Anand Agricultural University, Gujarat, India. The study was carried out in two phases: Phase 1- Pretreatment of seeds for enhanced germination; Phase 2- Evaluation of transplanted seedlings obtained from pretreated seeds for enhanced plant growth. The seeds of W. somnifera and A. paniculata were subjected to various pretreatments viz., physical treatment, hormonal priming, biostimulant priming and biopriming (using microbes). The seeds kept for germination without any pretreatment were taken as the control. In the first phase of the study in W. somnifera, seeds subjected to water soaking recorded higher germination (84.00 per cent), seedling length (13.30 cm) and seedling vigour index (11.16) which were on par with that of hot water treatment. Among the hormonal priming treatments, seeds exposed to GA3 @1500 μM recorded the highest germination (82.00 per cent), seedling length (14.40 cm) and seedling vigour index (11.80) which were found to be on par with GA3 @1500 μM. In biostimulant seed priming, PG @ 10μM primed seeds recorded higher germination (64.00 per cent), seedling length (10.57cm) and seedling vigour index (6.67) and were found to be on par with those of PG @ 1μM primed seeds. The biopriming treatments had no significant effect on germination and seedling length. However, significantly higher seedling vigour index was observed in all the biopriming treatments over the control treatment. Among all the pretreatments tried, water soaking treatment, hot water treatment, GA3 @ 1500μM was recorded significantly higher germination, seedling length and seedling vigour index. In the second phase of the study, the 30 day old seedlings of W. somnifera raised from pretreated seeds and untreated (control) seeds were transplanted and evaluated for plant growth and yield (shoot and root biomass), at harvest (120 DAS). Among the physical treatments, W. somnifera plants derived from water soaked seeds were observed to give higher plant height (60.80cm), number of branches (5.00), collar girth (0.47 cm), shoot biomass (fresh-37.61 g plant-1; dry -7.17 g plant-1) and root biomass (fresh-5.60 g plant-1; dry-0.79 g plant-1). These were observed to be on par in plants from hot water treated seeds, except for the number of branches and shoot biomass. Among the hormonal priming treatments, plants from GA3 @ 1500 μM primed seeds recorded higher plant height (55.57cm), shoot (fresh-27.73 g plant-1; dry-5.09 g plant-1) and root (fresh-5.60 g plant-1; dry-0.79 g plant-1) biomass. The plant height and shoot biomass were found to be on par with that of GA3 @ 1500 μM. In biostimulant priming, plants generated from PG @ 10 μM treated seeds gave the highest plant height (46.37 cm), shoot (fresh-21.40 g plant-1; dry-3.96 g plant-1) and root (fresh-4.36 g plant-1; dry-0.64 g plant-1) biomass. The plant height and shoot biomass were observed to be on par with that of PG @ 1μM. However, the highest number of branches and collar girth were recorded in plants raised from PG @ 1μM and SA @ 1500 μM primed seeds. Among the biopriming treatments, plants derived from the seeds treated with B. pumilis, recorded higher plant height (47.63 cm), number of branches (3.00), shoot (fresh-23.07 g plant-1; dry-4.39 g plant-1) and root (fresh-4.43 g plant-1; 0.63 g plant-1) biomass. The plant height and shoot weight was on par with that of P. fluorescens and the plants from the same treatment recorded the highest collar girth. Among the various pretreatments tried, plants raised from water soaked seeds gave better performance with respect to plant height, number of branches, collar girth and shoot biomass. The plants from hot water treated and GA3 @ 1500μM primed seeds gave the highest root biomass, which was observed to be on par with that in plants from water soaked seeds. In the first phase of the study in A. paniculata, seeds when exposed to physical treatments, higher germination (84.67 per cent), seedling length (15.93 cm) and seedling vigour index (13.38) were recorded in hot water treatment followed by scarification. Among the hormonal priming treatments, GA3 @1500μM primed seeds recorded the highest germination (82.00 per cent), seedling length (16.37 cm) and seedling vigour index (13.42). With respect to biostimulant seed priming, seeds treated with PG @ 1μM recorded higher germination (66.67 per cent) and seedling vigour index (6.03), while seedling length did not show any variation among the biostimulant treatments. Among the biopriming treatments, seeds primed with B. velezensis recorded the highest germination (82.67 per cent), seedling length (11.33 cm) and seedling vigour index (9.29). In A. paniculata, among all the pretreatments tried hot water treated as well as GA3 @ 1500 μM primed seeds recorded higher germination, seedling length and seedling vigour index. In the second phase of the study in A. paniculata, the 30 day old seedlings from pretreated seeds and untreated (control) seeds were transplanted and evaluated for plant growth and yield (whole plant biomass) at harvest (110 DAS). Among the physical treatments, A.paniculata plants derived from hot water treated seeds recorded higher plant height (55.77 cm), number of branches (21.67), collar girth (1.83 cm) and whole plant biomass (fresh-59.60 g plant-1; dry-21.90 g plant-1) at harvest. These were on par with those of scarified seeds. In hormonal priming, the highest plant height (56.80 cm), number of branches (20.00), collar girth (1.90 cm) and whole plant biomass (fresh-56.63 g plant-1 and dry-23.60 g plant-1) were observed in plants raised from seeds primed with GA3 @1500μM. Among the biostimulant priming, higher plant height (48.57 cm), number of branches (16.00), collar girth (1.20 cm) and whole plant biomass (fresh-38.97g plant-1 and dry-13.14g plant-1) were observed in plants raised from PG @1 μM primed seeds. On evaluation of plants derived from bioprimed seeds, those from B. velezensis primed seeds recorded the highest plant height (55.77 cm), number of branches (19.33), collar girth (1.50 cm) and whole plant biomass (fresh-53.97 g plant-1; dry16.87 g plant-1). Among all the seed pretreatments tried, plants generated from hot water treated and GA3@1500μM primed seeds recorded higher plant height, number of branches, collar girth and whole plant biomass. Among the various seed pretreatments tried, W. somnifera seeds exposed to water soaking, hot water and GA3@1500μM and A. paniculata seeds exposed to hot water treatment and GA3@1500μM recorded superior performance with respect to seed germination, seedling vigour, plant growth and yield.ThesisItem Open Access Economic Feasibilityb of Betelvine as an Intercrops in Rubber Holdings of Mavelikkara Taluk(Department of Plantation Crops and Spices, College of Horticulture,Vellanikkara, 1993) Vijayakumari, P R; KAU; Nazeem, P AA study has been conducted to analyse the economic feasibility of betelvine as an intercrop in the rubber holding of Mavelikkara taluk . Only five units having betelvine as intercrop could be identified in this area. One hundred other holding 20 each of betelvine as pure crop, plantain as intercrop, plantain as pure crop having covercrop and without any intercrop were also selected for the study . The study revealed that only a small portion of the holding was occupied by the betelvine, when it was treated as an intercrop. The cost of cultivation was found to be very high when compared with other cash crops. This might be the reason for limiting the cultivation to a small portion. This was confirmed by the fact that betelvine as pure crop was also limited in extent. The benefit cost analysis of the above crops revealed that betelvine cultivation was highly profitable with a benefit cost ratio of 2.51 in the intercropped area and was significantly higher than that for plantain which is the other common intercrop. The soil analysis data showed that betelvine absorbed lesser nutrients than plantain . The rubber plants of betelvine intercropped area showed vigorous growth than other intercrops which was due to the regular irrigation and fortnightly application of organic manure to the betelvine. Though the cost of cultivation was very high for betelvine , it could be recommended as an intercrop in the rubber holdings where there is availability of water throughout the year since it ensures substantial weekly income for the grower and his family. Though betelvine could be treated as a perennial crop, the farmers choosing it as an intercrop in rubber holdings will have to sacrifice the same by the fourth year when the rubber canopy closes to the full extent. Hence, we can suggest betelvine as an intercrop in rubber holdings only if land is too scare for its monoculture.ThesisItem Open Access Comparative study of fertilizer recommendations based on soil and leaf analysis vis a vis blanket recommendations of rubber board(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1992) Rajendran, P V; KAU; Nazeem, P AA case study was made to assess the comparison of the dosage of fertilizer recommendation based on soil and leaf analysis vis-à-vis blanket recommendation of the rubber Board. Almost all estates in our country are practicing this method of fertilizer application and systematic data is available only from large estates.. Hence the case study was confined to Estate Sector. From the soil analytical values and economics of fertilizer usage of the nine estates studied, the following observations are made. 1. In general organic carbon status of the soil was found to be medium, though high values were also recorded in some fields. 2. The available phosphorus status of the soil was found to be low in most of the cases. 3. Except in one estate, all the estates were low in available potassium. The observation on the leaf analytical value are as follows: 1. Nitrogen status was in the medium range in most of the cases and only in few cases it is high. 2. Leaf phosphorus was found to be in medium to high range inspite of low available soil phosphorus. 3. Leaf potassium also followed same trend as leaf phosphorus. Economics of fertilizer usage based on soil and leaf analisis revealed the following: Savings in quantity as well as the cost of fertiliser could be made in seven estates. The cost of fertilizer saved per hectare was found to be Rs. 31.23. Eventhough in two estates no savings in quantity as well as in the cost of fertilizer could be made by adopting discriminatory approach, it was possible to maintain the balance among the nutrients in these estates preventing the likely drop of yield.ThesisItem Open Access Evaluation of ocimum lines for herbage yield oil content and eugenol(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1988) Maya, S Nair; KAU; Sreekandan Nair, GInvestigations on “Evaluation of Ocimum lines for herbage yield, oil content and eugenol” was carried out at the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during 1985-86. Twentyfour Ocimum lines collected from different places from the state and the country along with one strain (Clocimum) released from RRL-Jammu were evaluated adapting simple lattice design with the following objectives. 1) To select better types based on leaf colour aroma and flavour, 2) To study the growth and flushing behaviour of each type and to isolate superior ones having better flushing characters; 3) To select a purple coloured O. sanctum line for the Kerala homesteads; 4) To select eugenol rich strains to undertake large scale cultivation of Ocimum for essential oil production; 5) To explore the possibility of growing Clocimum under Vellanikkara conditions. The crop was raised adopting the standard package of practices recommendations. The main growth parameters studied were plant height, spread, height at first branching, total number of branches per plant, number of days to blooming, intervals of flushing and leaf area. The yield parameters studied were herbage yield per plant, herbage yield per hectare, oil content, oil yield per hectare. An attempt was also made to relate leaf colour and aroma with the eugenol content of different Ocimum lines. The results indicated that the plant height increased with the age of plants. The plant spread and total number of branches per plant were maximum during July-August and afterwards a definite pattern was not observed. Clocimum and O. gratissimum lines branched at lower heights compared to O. sanctum lines. In general, all the lines tested took more time to initial flowering after transplanting, than after first or second harvests. Clocimum and O. gratissimum lines exhibited a tendency for quick flushing but took more days for flowering after each harvest compared to O. sanctum lines. O. gratissimum lines including Clocimum have higher leaf area. The studies on yield parameters revealed that Clocimum was most superior with regard to herbage yield, oil content and eugenol followed by O. gratissimum lines. Clocimum produced a herbage yield of 59.36 tonnes/ha/year. While the highest yielder of O. sanctum produced only 22.93 tonnes/ha/year. The different lines in general, produced maximum herbage and oil yield during second harvest, followed by the third and first harvests, whereas the oil content was maximum during the third harvest followed by the second and first harvests. The percentage of eugenol was maximum in Clocimum (71.82 per cent) followed by a purple coloured O. sanctum line (59.05 per cent) collected from Nellankara, near Trichur. Clocimum produced maximum eugenol per hectare followed by O. gratissimum lines. The scoring on leaf colour and aroma with respect to eugenol content revealed that, green leaved lines had better aroma than purple leaved with one purple coloured line as exception. Here also Clocimum proved its superiority. Economics of cultivation and distillation of different ocimum lines revealed that cultivation of Clocimum is more profitable than all other Ocimum lines evaluated. When we consider the various characters of 25 different Ocimum lines, it is very well clear that Clocimum can be groomed as a commercial crop under Kerala conditions. If there is a preference for purple coloured type of O. sanctum (Krishna Thulsi) the line from Nellankara can be recommended especially for the homesteads. Hence, further investigation to probe the possibilities of growing these promising lines as pure and mixed crops in Kerala and techniques for identifying valuable chemical constituents other than eugenol is suggested.ThesisItem Open Access Deficiency symptoms of mineral nutrients in clove (Syzygium aromaticum (L.) Merr. and Perry).(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1989) Nazeem, P A; KAU; Sivaraman Nair, P CExperiments were conducted at the College of Horticulture on nutritional aspects of clove, to study the nutrient deficiency symptoms as well as the distribution pattern of nutrients in starved clove plants. The deficiency symptoms were induced in clove seedlings in sand culture. The distribution pattern of P, S (anions) and Ca (cation) were studied in the nutrient-starved seedlings employing radio isotopes. Besides, the annual nutrient removal and the seasonal fluctuations in the foliar nutrient concentration were studied in bearing clove trees. Older leaves were the first to exhibit 'hunger signs' due to the stress induced by N, P, K and Mg starvation whereas the symptoms, were manifested on the younger growth due to deficiency of Ca, S, Fe, Mn, Cu, Zn and B. General yellowing of the older leaves and early defoliation were the symptoms expressed by N-starved plants. Phosphorus stress resulted in small brownish spots to appear on older leaves of clove seedlings which later coalesced to form necrotic patches.ThesisItem Open Access Optimizing propagation techniques in neelayamari (Indigofera tinctoria L.)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Mekha Mariam, Abraham; KAU; Krishnakumary, KIndia is acknowledged as one of the world’s richest treasure trove of medicinal plants. Neelayamari (Indigofera tinctoria L.) commonly known as ‘Indian indigo’, is a commercially grown leguminous plant of medicinal importance. The extract of the leaves is reported to have remarkable effect on hair growth and in preventing juvenile greying of hair. Due to the presence of many worthy phytochemicals, the crop is being documented in ‘Ashtangahridaya’ and is being cultivated by several pharmaceutical entrepreneurs, both in public and private sector. Like most of the medicinal plants, the cheapest method of propagation of this crop is through seeds. However, poor germination and vigour of seeds is a major problem in Neelayamari. In addition, heavy loss in seed yield occurs due to the splitting of pods at maturity. The study ‘Optimizing propagation techniques in Neelayamari (Indigofera tinctoria L.)’ was conducted in the Department of Plantation crops and Spices, with the objectives of standardizing the physiological maturity stage in Indigofera tinctoria L. for seed harvest, presowing seed treatments to enhance seed quality and longevity and vegetative propagation technique in Indigofera tinctoria L. through stem cuttings. In order to assess the stage of attainment of physiological maturity for seed harvest in Neelayamari, flowers were tagged on the day of anthesis and the pods were harvested at five days interval from 30 days of anthesis up to the pod splitting stage (63 days after anthesis). It was observed that the values of pod, seed and seedling characters increased up to 45 days after anthesis to reach their highest and thereafter declined till the pod splitting stage (63 days after anthesis). Germination and vigour indices at 45 days after anthesis were 73.80 per cent, 485 and 294 respectively and those at the pod splitting stage were found to be 31.33 per cent, 132 and 65 respectively. Hence, it was inferred that the seeds of Neelayamari reached physiological maturity stage by 45 days after anthesis. The seeds harvested at physiological maturity were dried to 8 per cent moisture content and subjected to various seed treatments before being packed in 700 gauge polyethylene bags. Untreated seeds served as the control. The seeds were stored under ambient conditions upto six months. The scarification treatments included treatment with Conc. H2SO4 for 5, 10 and 15 minutes, mechanical scarification with sand, hot water treatment at 80oC for 20 minutes and 60oC for 30 minutes and hydration for 24 hours. The quality parameters of the stored seeds were recorded at monthly intervals during the storage period and were put for germination test in sterilized sand media. Results pointed out that most of the seed treatments were effective in enhancing germination. High initial germination was recorded in mechanically scarified (95.83 %) and hydrated seeds (93.27%), while the untreated seeds showed a germination of 74.33 per cent. Vigour index I (703 and 698 respectively) and II (430 and 428 respectively) were also the highest in these treatments. Seed treatment with sulphuric acid, however, proved to be detrimental. Seed treatment also helped in extending the viability of the seeds. Mechanically scarified and hydrated seeds retained their germination above 60 per cent for six months during storage (65.67% and 63.67% respectively), while, in untreated seeds, germination reached 61.33 per cent at four months of storage and declined to 44.34 per cent by six months of storage. Seeds treated with sulphuric acid never attained the germination of sixty per cent throughout the storage period and those treated with sulphuric acid for 15 minutes failed to germinate at sixth month of storage. EC was found to be the lowest in hydrated seeds (0.0011 dSm-1) and mechanically scarified seeds (0.0012 dSm-1). The results thus indicated that mechanical scarification of seeds or hydropriming for 24 h can not only improve seed germination and seed quality but also prolong the longevity of the seeds. It was also noticed that all the seed quality parameters declined along the storage period. Attempt to assess the possibility of vegetative propagation in Neelayamari was carried out using hardwood, semi-hardwood and softwood cuttings, exposed to varying doses of IBA (250 ppm, 500 ppm, 750 ppm, 1000 ppm, 1500 ppm, 2000 ppm and 2500 ppm) and charcoal slurry dip. The cuttings were planted in polythene bags and were maintained in a mist chamber. Initially, the experiment was conducted during summer season and only the softwood cuttings treated with 2000 (8.89%) and 1500 ppm IBA (5.53%) survived after 60 days of planting, while all others withered and dried off. The experiment was then repeated during rainy season and the best results were obtained in the season. Softwood cuttings treated with 2000 ppm IBA during rainy season exhibited early sprouting (7.18 days) and a field establishment of 70.67 per cent. In comparison, the semi-hardwood and hardwood cuttings exhibited very low establishment rates of 21.77 per cent and 17.90 per cent respectively. Hence, it was evident that vegetative propagation using softwood cuttings treated with 2000 ppm IBA during rainy season can be relied upon as an alternative propagation method in Neelayamari.ThesisItem Open Access Stock scion interaction in Piper nigrum L. grafts(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Sarga George; KAU; Sujatha, V SBlack Pepper (Piper nigrum L.) also called ‘King of Spices’ and ‘Black Gold’, is one of the most widely used spices in the world, occupying a position that is supreme and unique. India is one among the countries where black pepper is being widely cultivated. However our productivity is low compared to other pepper producing countries in the world. Among the various factors limiting the productivity of Indian pepper, a soil borne disease called foot rot caused by Phytophthora is of prime importance. Piper nigrum is highly susceptible to Phytophthora foot rot. It has been reported that some South American Piper spp. are immune to Phytophthora. Interspecific crossing between Piper nigrum and immune species has not been successful so far. Grafting on resistant rootstock is a method to escape soil borne inoculum. The present study was conducted to assess the stock and scion interaction in grafts of Piper nigrum L. on different South American species of Piper immune to Phytophthora foot rot and to standardize the best time of grafting. The study was carried out as three experiments, viz., grafting studies, anatomical studies on Piper species and anatomical studies on graft union at different stages of development. Orthotropic as well as plageotropic shoots of P. nigrum, variety Panniyur 1 was grafted on three South American Piper species viz., P. colubrinum, P. auduncum and P. arboreum. Grafting of Piper nigrum on the same species was also done to study the feasibility of such grafting. The trial was laid out in completely randomized design. When orthotropic shoot of P. nigrum was used as scion, highest grafting success was recorded by the grafts of P. nigrum on the same species (100%) followed by the grafts on P. colubrinum (96.66%), P. auduncum (66.66%) and P. arboreum (46.66%). Graft survival after one year of grafting was 90.00, 83.33 and 33.33 per cent for P. nigrum/P. nigrum, P. nigrum/ P. colubrinum and P. nigrum/ P. auduncum grafts respectively. Survival of P. nigrum grafts on P. arboreum was very limited. None of these grafts survived for more than three months after grafting. Irrespective of rootstocks, the best month identified for grafting orthotropic shoot of P. nigrum was March. Although, self grafts showed highest per cent success in grafting, based on the growth of grafted plants (six month old), grafts on P. colubrinum was found to be the best with highest plant height (120.55 cm), number of nodes (18.91) and internodal length (6.32 cm). The graft recovery was less when plageotropic shoot of P. nigrum was used as scion. The highest per cent success was recorded by the grafts of P. nigrum on the same species (93.33%) followed by the grafts on P. colubrinum (66.66%), P. auduncum (36.66%) and P. arboreum (26.66%). March was identified as the best month for grafting plageotropic shoot of P. nigrum on P. nigrum, P. auduncum and P. arboreum. However, grafts on P. colubrinum performed best when grafted during June. Graft survival after one year of grafting was 66.66, 30 and 16.66 per cent for P. nigrum/P. nigrum, P. nigrum/ P. colubrinum and P. nigrum/ P. auduncum grafts respectively. Survival of P. nigrum grafts on P. arboreum was very limited. As far as the growth of grafted plants was concerned, highest growth was shown by the grafts of P. nigrum on the same species. In the anatomical studies of Piper spp. it was observed that, Piper species exhibited a peculiar arrangement of vascular bundles. Two rings of vascular bundles comprising of an outer, cortical and an inner, medullary bundles were observed in all the four Piper species examined. Mucilage canal was present only in P. nigrum while an additional medullary bundle was observed in P. colubrinum. Large pith region was the characteristic feature of P. auduncum and P. arboreum. Examination of graft union at three, six and twelve months after grafting revealed that, graft union formation was completed by six months after grafting. One year old P. nigrum/ P. colubrinum grafts and P. nigrum/ P. auduncum grafts exhibited the formation of a dense necrotic area at the graft interface. Based on the observations, it can be concluded that, due to the peculiar arrangement of vascular bundles in Piper species, matching of all the vascular bundles of stock and scion is difficult. However, complete union of parenchymatous tissues of stock and scion was formed within six months after grafting. But, a proper cambial connection between the grafting partners was not evident. Further studies need to be conducted to find out the reasons for the development of dense necrotic area at the graft interface.ThesisItem Open Access Effect of spacing and planting material on the growth, yield and active principle in Plumbago rosea L.(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1990) Subha, S; KAU; Sreekandan Nair, GInvestigations on "Effect of spacing and planting material on the growth, yield and active principle in Plumbago rosea L." was conducted at the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during 1987-88, using factorial RBD design for exploiting this valuable medicinal plant with the following objectives: (1). To standardise the size of shoots as planting material for commercial cultivation. (2). To standardise the best spacing for better growth, yield and active principle. (3). To explore the possibility of growing Plumbago rosea L. as a commercial crop. (4). To explore the possibility of grooming this plant as an annual plant.ThesisItem Open Access Flower bud differentiation in piper sp.(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1985) Rajan, P S; KAU; Mohanakumaran, NStudies were undertaken at the College of Horticulture, Vellanikkara during 1983-’84 in Panniyur-1 and Karimunda varieties of pepper to collect information on the factors influencing flower bud differentiation and on the histological aspects of the process. Among the climatic factors maximum and minimum temperature during the preceding summer as well as the monsoon showers exhibited significant positive correlation with flower bud differentiation process. Among the nutritional factors studied, carbohydrates and C/N ratio were found to be high prior to the peak differentiation period. However, these failed to show significant statistical correlation. Significant accumulation of nitrogen was found in the shoots prior to differentiation. Phosphorus and potassium contents were not correlated with the process. Inhibitor content of the shoots prior to differentiation was found to negatively influence the process. Peak period of differentiation was observed from the middle of June to the end of July in Panniyur-1, while it was a little advanced in Karimunda (from the beginning of June to the middle of July). There were no fundamental differences in the histological aspects of flower bud differentiation between the two varieties. The bud which was conical during the vegetative phase changed into a dome shaped structure during the transition. Afterwards, this grew into a cylindrical structure on the sides of which bract and flower primordial developed in aeropetal succession. Differentiation and development of ovary wall, integuments, ovules, pollen sacs, pollen grains etc. followed. The whole process of differentiation was completed within about 25 days of its commencement.
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