PhD Thesis

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    Potassium utilization efficiency and seasonal response in photosynthates partitioning of high yielding sweet potato varieties
    (Department of Agronomy, College of Agriculture ,Vellanikkara, 2023-05-19) Jeena Mary; Prameela, P
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    Genetic studies in sweet potato (ipomoea batatas(l.)lam.) a biometric approach
    (Department of Agricultural Botany, College of Agriculture, Vellayani, 1979) Joseph, C A; Mary George, K
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    Genic manipulations in sweet potato adopting induced mutations
    (Department of Agricultural Botany, College of Agriculture,Vellayani, 1989) Suma Bai, D I; Krishnan Nair, N
    An experiment was conducted at the Department of Agricultural Botany, College of Agriculture, Vellayani during 1987-1989 for genetic manipulations in sweet potato through gamma ray induced mutagenesis for increased variability and to isolate out genotypes having wider adaptability and better performance. Stem cuttings of 8 to 10 cm length bearing two nodes each, taken from fifteen sweet potato varieties were used for radiosensitivity analysis. Gamma irradiation was done by a 60 Co gamma cell unit installed in the Radio Tracer Laboratory of Kerala Agricultural University, Trichur. The material was subjected to exposure of 2-10 kR at intervals of 2 kR. The chosen dose rate was 0.162 MR/h. The direct effect of doses on the material was assessed on the basis of days to start sprouting, days to complete sprouting, sprouting percentage, vine length, branch and tuber number and weight of tubers per vine. The exposures above 4 kR caused lethality in the majority of the varieties and hence comparative analysis for ratiosensitivity was assessed at the 2 kR level. The gamma ray exposed population started sprouting late. The days taken for completion of sprouting were also more in all the varieties. Gamma rays, in addition, reduced the sprouting percentage. The percentage lethality varied depending on variety. The vine length and number of branches per vine also varied from variety to variety. They were found to be comparatively less in treated population. The tuber number and weight of tubers per vine were found to be significantly increased by gamma irradiation at 2 kR. Based on the above observations the fifteen varieties were classified into three, viz. low, medium and high radiation sensitive categories. Induced mutagenesis was done in continuation with the radiosensitivity analysis using three varieties, each selected from the low, medium and high radiation tolerant groups. The planting materials selected for gamma irradiation included fresh cuttings, rooted cuttings and rooted tubers which were exposed to radiation at a range of 500 – 2500 r, at 500 r intervals. The dose rate was 0.162 MR/h. The irradiated materials along with the control were planted on the subsequent day. In vM1 generation the direct effect of gamma rays was assessed based on days taken to start sprouting, days taken to complete sprouting, sprouting percentage, lethality on the 30th day of planting and at harvest, vine length, branch number per vine, fresh weight of vine, tuber number per vine, weight, length, girth and volume of tuber and tuber yield per vine. From vM1 plants 3-4 noded cuttings were taken from the basal, middle and top portions for raising vM2 generation. VM3 and vM4 generations were also raised in the same manner. In vM2, vM3 and vM4 generations the yield parameters were analysed in detail. Classification of the phenotypes and frequency analysis were also done. The salient findings of the experiment are the following: There was a delay in sprount initiation and for completion of sprouting caused by gamma ray exposure. A decrease in sprouting percentage and an increase in lethality were noticed under higher levels of exposures. Similarly a reduction in vine length and branch number per vine were found at higher exposures. The fresh weight of vine was reduced and the tuber number increased at higher exposures. There was an increase in mean tuber weight, length, girth, volume and tuber yield per vine at higher exposures. All the exposures and the different modes of treatment induced phenotypic variants both in negative and positive directions. Positive variants were in higher frequency in later generations. Irradiation of rooted cuttings was found to be more economical or beneficial compared to fresh cuttings and rooted tubers. The study enabled to isolate out two promising types, one each from S5 and Bhadrakalichuvala. These mutants outyielded the control and are being multiplied by vine cuttings for farm trials in different agroecological milieus of the State.
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    Characterization, host range and management of sweet potato feathery mottle virus
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2001) Jeeva, M L; Balakrishnan, S
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    Nutrient- moisture interaction under phasic stress irrigation of sweet potato in summer rice fallows
    (Department of Agronomy, College of Agriculture,Vellayani, 1994) Muraleedharan Nair, G; Muraleedharan Nair,V
    A field experiment on sweet potato was laid out in the rice field fallowed during summer season at the Instructional Farm, College of Agriculture, Vellayani. The study was intended to work out of the irrigation schedule and fertilizer practice for sweet potato grown as a catch crop during the summer season of 1990 and 1991. The experiment was designed to economise the use of irrigation water as well as fertilizers by inducing phasic stress at certain phases of plant growth which are considered critical for sweet potato. The field experiment was laid out in a strip plot design replicated thrice with irrigation in horizontal strips and fertility levels in vertical strips. Irrigation water at full CPE was given during tuber initiation phase (10-30 DAP), full CPE at tuber maturity phase (80-100 DAP) and full CPE at tuber initiation and tuber maturity phases. The crop received irrigation at ½ CPE during the rest of the period of plant growth. Nitrogen and potassium were applied @ 25, 50 and 75 kg ha-1 and a uniform dose of P2 O5 @ 50 kg ha-1 and lime @ 500 kg ha-1 were applied. A control plot that received NPK @ 75:50:75 kg ha-1 and FYM @ 10 t ha-1 was maintained for treatment comparison. Growth characters were recorded at an interval of 21 days from planting and it was observed that providing irrigation at full CPE during tuber initiation phase resulted in significant increase in vine length and number of leaves plant-1. Enhanced rate of application of Nitrogen promoted the growth of vines, number of branches plant-1 and number of leaves produced plant-1. Potassium did not exert any influence on these growth characters. Growth analysis studies showed that the LAI was maximum in plots that received irrigation at full CPE during tuber initiation phase. Nitrogen substantially influenced the LAI, higher levels being significantly superior to the lower levels. Higher levels of potassium also influenced the LAI. The NAR and specific leaf weight were the highest in plots that received irrigation at ½ CPE during tuber initiation phase. Both NAR and CGR were high in the early stage of plant growth and decreased towards harvest. Increased rates of nitrogen supply decreased the NAR and specific leaf weight whereas no definite trend could be observed on CGR> Higher levels of potassium had a favourable influence on NAR and CGR. The dry matter of leaves, shoots, fibrous roots and tubers were significantly enhances by providing full CPE during tuber initiation phase. Increasing the level of nitrogen, influenced the dry matter in the aerial parts. The influence of K on dry matter production was not consistent. Tuber bulking rate showed a positive trend under irrigation at full CPE during tuber initiation phase. Nitrogen levels at 50 and 75 kg ha-1 had an overlapping influence on tuber bulking rate and both remained superior to 25 kg ha-1. Scheduling of irrigation did not exert any influence on the length and girth of tuber. However, an increase in the length and a corresponding decrease in the girth were noticed at enhanced rates of nitrogen supply. The number of tubers plant-1 showed a significant improvement by providing irrigation at full CPE during tuber initiation phase. The total number of tubers plant-1 was increased by high rates of N, but did not influence the number of marketable tubers. Application of K at 50 kg ha-1 promoted the production of more tubers. Tuber yield was significantly influenced by irrigation wherein providing full CPE during tuber initiation phase resulted in superior yield of both total and marketable tubers. Tuber yield was maximum at 50 kg ha-1 each of nitrogen and potash. Vine yield was significantly enhanced by higher rates of applied nitrogen. The harvest index and utilization index were enhanced by the application of irrigation water at full CPE during tuber initiation phase. Application of N at 25 kg ha-1 resulted in the production of high starch content whereas the sugar content was increased upto the highest level of 75 kg ha-1. The uptake of nitrogen by vines and tubers showed a progressive increase by applying full CPE during tuber initiation phase. Application of higher levels of nitrogen invariably promoted the uptake of N, P and K by the plant. Application of potash at 50 or 75 kg ha-1 also resulted in higher uptake of potassium. The fertility status of the soil did not show a positive trend by scheduling of irrigation. The plots that received the lowest dose of nitrogen, invariably recorded the highest level of available phosphorus. Available potassium content was also high in plots that received higher rates of potash. Irrigation at full CPE during tuber initiation and/or tuber maturity phase recorded significantly higher water use efficiency and net returns as compared to including stress during tuber initiation phase. Nitrogen and potash both at 50 kg ha-1 recorded the maximum water use efficiency and net returns from sweet potato cultivation.
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    Integrated control of sweet potato weevil Cylas formicarius Fabricius
    (Department of Entomology, College of Agriculture, Vellayani, 1987) Palani Swami, M S; Mohandas, N
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    Cultural, manurial and water requirements for sweet potato (Iponoea batatas (L) Lam.)
    (Department of Agronomy, College of Agriculture, Vellayani, 1989) Oommen, M; Sadanandan, N
    Three field experiments were conducted in the wet lands and garden lands of Instructional farm of College of Agriculture, Vellayani to work out cultural, manurial and water requirements for sweet potato. The treatments in the first experiment – Nutritional requirements of sweet potato – consisted of three level of nitrogen (50, 70 and 100kg N/ha), three levels of phosphorus (25, 50 and 75kg P2O5/ha) and three levels of potassium (50, 75 and 100kg K2O/ha). The experiment was laid out in a 33 partially confounded factorial design with two replications. The second experiment – spacing cum depth of application of fertilizers – consisted of three spacing (40cm x 20cm, 60cm x 20cm and 80cm x 20cm) and three depths of application of fertilizers (10cm, 20cm and 30cm). The experiment was laid out in a 32 factorial design in RBD with four replications. The third experiment – Irrigation requirement – consisted of four levels of irrigation (IW/CPE ratios 0.25, 0.50, 0.75 and 1.00) and four levels of fertilizers (50:25:50, 75:50:75, 100:75:100 and 125:100:125 kg N,P and k/ha). The experiment was laid out in a split plot design with five replications. In the experiment to study the nutritional requirement of sweet potato growth attributes like length of vine, number of branches and leaf area index were maximum at higher levels of nitrogen and potassium. The highest values of tuber number, tuber weight, length of tuber and girth of tuber were obtained by the application of 75kg N, 50kg P2O5 and 100kg K2O/ha. Application of nitrogen, phosphorus and potassium at the rate of 75:50:100 kg/ha was found to be optimum for higher tuber yield. While nitrogen nutrition increased the protein content of tuber, potassium application enhanced the starch content. Highest levels of nitrogen, phosphorus and potassium increased the leaf, stem and tuber dry matter production and tuber bulking rate. Potassium only did influence the net assimilation rate. Crop growth rate was maximum at higher levels of nitrogen, phosphorus and potassium. The plant uptake of nitrogen, phosphorus and potassium was maximum at the highest level of these nutrients. The NPK combination of 75kg N, 50kg P2O5 and 100kg K2O/ha resulted in the maximum net return. Experiment on spacing cum depth of application of fertilizers revealed that wider spacing of 80cm x 20cm enhanced the growth characters such as length of vine, number of branches and LAI. Depth of application was not influential on this aspect. Yield attributes like tuber number, tuber weight and girth of tuber were higher at the spacing of 40cm x 20cm but length of tuber was maximum under wider spacing. Application of fertilizers at 20cm depth recorded maximum values for the aforesaid characters. Closer spacing of 40cm x 20cm and 20cm deep placement of fertilizers recorded higher tuber yield. Among the quality attributes protein content alone was influenced by wiser spacing, but protein and starch contents were increased when fertilizers were applied at 20cm depth. Wider spacing increased leaf and stem dry matter and CGR while closer spacing recorded higher tuber dry matter, tuber bulking rate and net assimilation rate. Depth of application of fertilizers did not influence the dry matter production. Plant uptake of nitrogen, phosphorus and potassium was increased by wider spacing and by the application of fertilizers at a depth of 20cm. A combination of 40cm x 20cm spacing and 20cm deep fertilizer placement resulted in maximum net return. Experiment on irrigation requirements divulged that highest IW/CPE ratio and higher fertilizer combinations recorded maximum length of vine and LAI, but number of branches was not influenced by them. Number of tubers, weight of tubers, length of tubers and girth of tubers were not influenced by irrigation, while levels of fertilizers increased the length of tubers. Tuber yield was higher at IW/CPE ratio of 0.75. Fertilizer combination of 100:75:100 kg of N, P and k/ha produced the maximum yield. Starch and protein contents were increased at higher levels of irrigation and fertilizer application. Total dry matter production and bulking rate increased upto an IW/CPE ratio of 0.75 and upto a fertilizer lever of 100:75:100 kg N, P and k/ha. Plant uptake of nitrogen, phosphorus and potassium at harvest was maximum at higher levels of irrigation and fertilizer application. Irrigating the field when the IW/CPE ratio becomes 0.75 and application of fertilizers at a ratio of 100:75:100 kg N, P and k/ha recorded maximum net returns.
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    Developing complimentary food products based on cassava and sweet potato
    (Department of Home Science, College of Agriculture, Vellayani, 1995) Chellammal, S; Prema, L
    The present study on developing complementary foods based on cassava and sweet potato was under taken to utilize the high energy root crops such as cassava and sweet potato for the development of complementary foods and to ascertain their nutritional adequacy, physiological tolerance, organoleptic and shelf life qualities. The survey on the consumption of processed foods indicated that all the families surveyed were aware of the different processed foods available in the market irrespective of the family income. Variables like, food expenditure family income, educational status of the housewife, number of children in the family and family size were found to have a positive correlation with the consumption of processed foods. The employment status of the women had a significant correlation with the consumption of the processed foods. In high income families, the consumption of processed foods was more among unemployed women. Employed women of high middle income families consumed more processed foods than unemployed women of that category. But the employment status of women did not make any significant difference among the middle income families with regard to the consumption of processed foods. Type tests administered for the raw ingredients revealed that the moisture content for all the raw ingredients were lower than ISI specified values. And low moisture values were advantageous in product development. Protein and ash content of certain ingredients were slightly lower than ISI prescribed values but the difference was not statistically significant. Type tests administered for the products revealed that all the characteristics were comparable with ISI specifications. Regarding physical characteristics sweet potato noodles secured lower scores than cassava and standard noodles for different quality parameters. However the developed macaronis were equal or better in physical characteristics. Cooking time for the extruded foods were on par with standard products. The bulk density of standard noodles was significantly lower than cassava and sweet potato noodles. Bulk density of macroni was higher than that of noodles in all the three categories. All the foods developed had essential nutrients in optimum quantity. When the nutrients were computed they were observed to be slightly higher indication loss during processing. The loss was statistically significant for protein and carotene in the extruded foods. Assessment on the physiological tolerance revealed that among the experimental groups weaning mixes exhibited higher values for P.E.R. B.V, D.C and N.P.U which were comparable with the control group. The PER of the developed foods were 1.99 and above, indicating that the quality of protein is good. The study on the organoleptic qualities of the developed food revealed that cassava based foods could be rated as equal or even better on certain quality parameters than standard. Sweet potato based foods secured lower scores. Women from high income group who were the predominant consumers of processed foods, fully agreed with the judgment of technical experts. All the foods developed, were rated positively by majority of the farm women. Regarding shelf life qualities, the storage containers had significant effect on the moisture level and peroxide value of the stored products. However the storage containers did not have any significant influence on the total sugar content. There was increase in all the three quality parameters throughout storage period, the highest being in polythene bags followed by steel containers. There was no insect infestation upto 6 months of storage period irrespective of containers and products . Products stored in glass and plastic containers were free of insect infestation through out the storage period of one year. Among the other two containers the infestation was more in polythene bags than in products stored in steel containers. The insects identified were S.orysae, T.castaneum and A. Fasciculatus. Microbial status after the storage period, revealed that there were five samples in which there was neither fungal nor bacterial growth. Though there was fungal or bacterial growth in other samples the count was within the maximum limit specified by ISI. The technologies developed in the present study could be transferred to unemployed youth and women so that they can start small scale processing units which is the present lacunae in food processing industry in our country.