PhD Thesis
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Item Potassium supplying capacity of Neyattinkara- Vellayani soil association and its relationship with potash nutrition of major crops on them(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1989) Valsaji, K; Subramonia Aiyer, RDetailed study on the potassium supplying capacity of Neyattinkara-Vellayani soil association and its relationship to potash nutrition of major crops on them namely coconut and cassava has been made. This soil association represents the red loam soil type and consists of Neyattinkara series tentatively classified under Typic Eutropepts and Vellayani series under Typic Tropudalfs. Soil samples were collected from selected fields under coconut and cassava for the dominant soil types namely sandy clay loam and sandy loam soils under Neyattinkara and Vellayani series. To find the most suitable depth and location of soil sampling for coconut samples were also drawn at two different depths of 0-30 and 30-60 cm from basins and interrows. Empirical methods, quantity intensity studies, electro ultrafiltration studies and foliar diagnostic techniques were employed to decide on the most suitable method for plant available K. The various intensity, quantity and capacity factors which relate the readily available, difficultly available and storage or buffer capacity were assessed for a proper appraisal of the K status and supplying capacity. The various soil K parameters such as total K, water soluble K, exchangeable K, available K, nonexchangeable K, HNO3 extractable K, H2SO4 extractable K, sodium tetraphenylboron extractable K and percentage K saturation were found to be low. The water soluable K formed higher proportion of available K than exchangeable K. Interrelations showed that water soluble K, exchangeable K and available K are in dynamic equilibrium. Nonexchangeable K did not show any relationship with available K indicating that it is a poor source of available K. Quantity-intensity studies showed that the shape of the Q/I curve was similar in all types of soil since they belong to a group of related soils. The Q/I parameters like Are.K, Ko, Kx. KL and potential buffering capacity values were low. The KL values were higher than NH4OAc.K. The free energy values were found to be high indicating easy release rates of K. For both coconut and cassava, the leaf K did not show any consistent relationship with the soil K parameters. Among the Q/I parameters, KL had significant relation with leaf K of coconut. EUF 10 and EUF 35 showed significant relationship with leaf K of both coconut and cassava. Electro-ultrafiltration studies showed that the easily desorbed K was more than the strongly desorbed K indicating easy supply rate. The EUF 30-35 values were related to HNO3.K showing that this fraction included some initially nonexchangeable K. EUF 10 had significant relation with exchangeable K and EUF 35 had significant relation with exchangeable and available K. The buffer parameters BK (EUF 10/EUF 30) and EUF.Q (EUF 30-35/EUF 30) values were low indicating low buffer capacity. The EUF desorption pattern showed that the first peak was within 10-20 minutes and prominent than the second peak. This indicated low reserve K but easy supply rates. The EUF desorption curve of soils with high NH4OAc.K was above that of soils with low NH4OAc.K. This indicated that with increase in NH4OAc.K the easily desorbed K also increased. The yield of coconut and cassava were related to the various K parameters to evaluate the suitability of different methods for available K. In most of the cases NH4OAc method was found to be suitable for both coconut and cassava. Leaf analysis was also found to be suitable. For cassava the result obtained after 41/2 months is meaningless for the current crop. For coconut collection of index leaf is laborious. It was also found that the Q/I and EUF were suitable for coconut. But these methods cannot be followed in routine soil testing because of the high input of laboratory work involved. Considering these aspects it was found that NH4OAc method is the most suitable one because it is simple, cheap and easy to adopt. Based on the NH4Ac.k content the fertility status was found to be low to medium. The various intensity, quantity and capacity factors of soil K, Q/I and EUF parameters revealed that this soil association has low K supplying capacity. Hence heavy dose of K fertilizers is required. Split application is preferable especially in sandy loam soils to reduce leaching losses. NH4OAc.K which was found as a suitable indicator of plant available K varied significantly in basin and inter-row samples of sandy clay loam soils. This K fraction did not vary with depth in both sites. In general, the K nutrient index indicated that the basin samples had a higher level than inter-row and surface samples. Thus basin sampling at 0-30 cm depth was found to be the ideal site of soil sampling for coconut tree.Item Biology, Bionomics and control of coconut cockchafer Leucopholis coneophora Burm.(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1983) Abraham, V A; Mohan Das, MThe biology of the coconut cockchafer Leucopholic coneophora Burm. was studied in detail for the first time. Techniques for rearing the pests from egg to adult in potted palnts kept in field were standardized. The egg laying behaviour of adults was observed. The morphological changes off eggs, different instars of grubs and pupae during development were studied in detail. The changes in immature stages of male and female insects were traced separately. The general morphology of different instars of the grubs was studied in full with a view to finding distinct identifying characters for each.Item Production potential of cassava (Manlhot esculent a Grants) intercropped in coconut gardens(Department of Agronomy, College of Agriculture, Vellayani, 1986) Ramakrishnan Nayar, T V; Sadanandan, NField experiments were conducted at the coconut Research Station. Balaramapuram during 1983-84 and 1984-85 to study the production potential of cassava varieties Sreevisakham and Malayan-4, intercropped in coconut gardens, as influenced by planting density, growth regulators and different levels of NPK fertilisers. The cassava hybrid Sreevisakham was superior to the popular cultlvar Maiayan-4 in nuirber of nodes plant 1, number of functional leaves plant™1, leaf area index, net assimilation rate, crop growth rates, dry matter production, utilisation index, tuber bulking rate and in fresh tuber yield. For intercropping one hectare of coconut garden in which coconuts are spaced at 7.5 x 7.5 m, cassava plant population of 8000 (spacing 90 x 90 cm) was found to be optimum to produce maximum fresh tuber yield* Cassava plants at higher planting density, were stunted in growth and produced poor quality tubers. The growth regulators cycocel and ethrel though decreased the plant height, could not Influence either the yield attributes or yield and quality of cassava tubers.Item Fertilizer Management of minor tuber crops in Coconut based cropping system(Department of Agronomy, College of Agriculture, Vellayani, 1989) Pushpakumari, R; Sasidhar, V KAn investigation was carried out to evolve the fertilizer management practices of minor tuber crops in coconut based cropping systems during the years 1985-86 and 1986-87. This investigation was carried out as two experiments. In experiment I, screening of minor tuber crops under varying intensities of shade was done adopting a split plot design with 4 replications. In experiment II the fertilizer management of minor tuber crops in coconut based cropping system was studied. The experiment II was conducted in randomised block design with 3 replications. While experiment I was taken up at the Instructional Farm, College of Agriculture, Vellayani, experiment II was conducted at Coconut Research Station, Balaramapuram. Shade had significant influence on the length of vine/height of plant, LAI, NAR, CGR, dry matter production chlorophyll content of leaves, starch and protein content of tubers and yield of tuber of greater yam, lesser yam, tannia and elephant footyam. With increase in shade intensity, the yield declined proportionately in greater yam and elephant footyam reocrding highest yield under open condition. The tuber yield of lesser yam under open and 25 per cent shade levels were statistically on par, beyond which a drastic reduction in yield was observed with increase in shade intensity. Tannia recorded highest yields under 25 per cent shade, with an almost equal yield under 50 per cent shade. Fertilizer levels did not significantly influence the growth and yield characters of lesser yam, elephant footyam and tannia. But for greater yam there was significant increase in plant height in the first year and tuber yield in the second year with increase in fertilizer level. Greater yam responded linearly to fertilizer levels recording maximum yield with full recommended dose of fertilizer, although the variation was significant only in the second year. Lesser yam had maximum yield at medium fertilizer level and elephant footyam at lowest level, though not significant. The general performance of tannia was very poor. The economics worked out for the fertilizer management practices of greater yam, lesser yam, tannia and elephant footyam revealed that among the four crops tried, elephant footyam gave the maximum net profit followed by greater yam and lesser yam. However, tannia resulted in a loss.Item Sequential analysis of constraints in increasing production of rice and coconut in Kerala(Department of Agricultural Extension, College of Agriculture, Vellayani, 1989) Prakash, R; Thyagarajan Nair, GThe study aimed at identifying the production constraints of rice and coconut and measuring the validity of identified constraints in selected production centres. The solutions to the identified constraints were also collected and their feasibility rated in order to formulate appropriate development strategies for increasing production of rice and coconut in Kerala. The study was conducted in all the NARP regions of the State, namely, Southern, Central, Northern, High Range and Problem Regions. The respondents of the study comprised of 160 farmers each for the identification and validation of constraints and 100 Research Workers, 100 Extension Workers and 57 Input Agencies for the indentification of constraints. To identify the production constraints of rice and coconut, Delphi technique – the methodology for elicitation of expert opinion – was used. Date from the farmers were collected using pre-tested structured interview schedules. Conversion of lands, drought and lack of irrigation were the major production constraints of rice ranked according to their importance in the Southern Region while nonavailability of FYM, low profitability and high cost of production were the constraints ranked high in the Central Region. High difficulty in cultivation, nonavailability of FYM and fragmentation were the production constraints of rice ranked high in the Northern Region. High wage rate of agricultural labour, indebtedness and high cost of production ranked high in the High Range Region. In the Problem Region, floods, low profitability and high cost of FYM were the high ranked production constraints of rice. In the case of coconut, lack of irrigation, drought and high wage rte of agricultural labour were the high ranking production constraints in the southern Region while low adoption of chemical fertilizers, high cost of fertilizers and lack of irrigation ranked high in the Central Region. In the Northern Region, the high ranking constraints were low adoption of plant protection chemicals, high cost of fertilizers and low labour productivity whereas high cost of seedings, high cost of fertilizers and pests and disease incidence ranked high in the High Range Region. Root (Wilt) diseases, high wage rate of agricultural labour and high cost of plant protection chemicals were the high ranking production constraints of coconut in the Problem Region. In the Southern Region, the production constraints of rice, namely, low adoption of chemical fertilizers, lack of knowledge about chemical fertilizers,, negative attitude towards plant protection chemicals, absentee landlordism, negative attitude towards HYV, low adoption of HYV and small farm size were found to be individually significant in predicting the yield of rice. Negative attitude towards HYV, low adoption of HYV, low labour productivity and lack of irrigation were individually found to be significant in predicting the yield of rife in the Central Region. In the Northern Region, the constraints namely, high cost of chemical fertilizers, low adoption of chemical fertilizers, indebtedness, lack of credit facilities and high incidence of pests and disease were found to be individually significant in predicting the yield of rice. Low adoption of HYV, incidence of pests and diseases, high cost of chemical fertilizers, low adoption of plant progection chemicals were found to be individually significant in prediction the yield of rice in the High Range Region. In the Problem Region, the constraints, namely, low adoption of plant protection chemicals, low adoption of chemical fertilizers, floods and incidence of pests and diseases were found to be significant in predicting the yield. The production constraints of coconut individually significant in predicting the yield in the Southern Region were low adoption of chemical fertilizers, drought and lack of irrigation. In the Central Region, lack of irrigation, lack of knowledge about plant protection chemicals, low adoption of chemical fertilizers and incidence of pests and diseases were found to be individually significant in predicting the yield of coconut. In the High Range Region the constraints namely nonavailability of quality seedings, small farm size, incidence of pests and diseases were individually significant in predicting the yield while low adoption of chemical fertilizers, incidence of pests and diseases and incidence of root (wilt) disease were significant production constraints in the Problem Region. Evolving varieties suited to different agro-climatic regions, promoting group farming, popularising cultivation of green manure seeds, providing fertilizer subsidy, providing crop insurance, fixing support price for paddy were found to be the most feasible steps to be taken for increasing production of rice in Kerala. Adoption of moisture conservation practices, decentralised nursery for coconut, supply of seedlings through Krishibhavans, large scale production of hybrid coconut, scientific replanting and underplanting programme and subsidising chemical fertilizers are the steps to be undertaken to increase the production of coconut in the State. Based on the results of the study, certain important implications have been spelt out.