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Subject: Agronomy × Author: KAU × End date: 1997 × Start date: 1997 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Response of cucumber (Cucumis melo L.) to drip irrigation under varying levels of nitrogen and potash
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Lakshmi, S; KAU; Sasidhar, V K
    Two field experiments and one observational trial were conducted in the Instructional Farm, College of Agriculture, Vellayani during 1992 and 1993 to study the effect of drip irrigation and application of N and K fertilizers on the growth and yield of cucumber. In the preliminary observation trial (Experiment I a) three levels of drip irrigation, (2, 3 and 4 I plant-1 day-1) four timings of irrigation (1, 2, 3 and 4 hours) and two number of drippers per plant (1 and 2 dripper plant-1) were evaluated and based on the results of this experiment, the number of drippers per plant and duration of drip irrigation was standardised. Experiment 1 b was conducted to standardise the method of application of fertilizers in Experiment 2 and 3 for which cucumber plants raised under different levels of drip irrigation (2, 3 and 4 I plant-1 day-1). This was conducted during April 1992. The results of these experiments indicated the duration for drip irrigation as 3 hours per day and one number of dripper per plant to be the best. The spread and depth of root system of cucumber plants raised under drip irrigation pointed out that the fertilizers as a ring around the base of the plant at a distance of 20 cm will be within the root zone of the plant. The experiments 2 and 3 were laid out in the field with three levels of drip irrigation (2, 3, and 4 I plant-1 day-1), three levels of nitrogen (35, 70 and 105 kg ha-1) with three levels of potassium (25, 50 and 75 kg ha-1) with three drip irrigation controls (2, 3 and 4 I plant-1 day-1) and farmer's practice. The yield of cucumber was highest at the drip irrigation level of 31 planr-1 day-1. Irrigation at this level favourably influenced the vegetative characters, yield attributes and yield. But root dry matter was not influenced by the different drip irrigation level while the root spread and root depth were highest at the drip irrigation level of 41 plant-1 day-1. When different levels of nitrogen applied were observed, the vegetative characters yield attributes and yield were found to be favourably influenced at 70 kg N ha-1. The root spread of cucumber was highest at the highest level of N applied (l05 kg ha-1). Potassium at 50 kg ha-1 produced the highest yield due to its favourable influence on the vegetative and yield characters. There was no influence of potassium on my of the root characters studied. The soil moisture status was highest up to 30 cm depth in all drip irrigated treatments while in pot watered plots, the soil moisture was higher in the lower layers below 30 cm. The field water use efficiency was highest at the drip irrigation level of 3 I plant-1 day-1, 70 kg nitrogen ha-1 and 50 kg potassium ha-1. The nitrogen, phosphorus and potassium uptake by the plants and fruits were highest at the drip irrigation level of 31 plant day I, 70 kg N ha-I and 50 kg K ha-I. The physical optium levels of drip irrigation was 31 plant -1 day -1, 93 kg N ha-1 and 65 kg K ha-1 in the first season. When another crop is repeatedly grown in the same field, the Nand K levels can be reduced to 75 kg ha-1 and 60. kg ha-1 but drip irrigation is required at the rate of 31 plant-1 day-1. This resulted in higher benefit cost ratio of 2.83 and internal rate of returns of 23%. The payback period of this project worked out to 1.13 years.
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    ThesisItemOpen Access
    Soil test crop response studies in cassava in laterite soils of Kerala
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Kumari Swadija, O; KAU; Sreedharan, C
    An investigation was undertaken at the College of Agriculture, Vellayani to establish soil test crop response correlation for soil test based balanced fertilizer prescription for cassava var. M-4 in laterite soils of Kerala. The field investigation consisted of fertility gradient experiment, STCR experiment and technology verification trial. The fertility gradient experiment was conducted during April- May 1994 in the Instructional farm, Vellayani. The desired gradient in soil fertility was created in one and the same field by applying graded doses of N, P and K fertilizers and raising fodder maize var. African Tall. The STCR experiment was conducted in the same field during June '94-March '95 using the test crop, cassava var. M-4. The treatments consisted of factorial combinations of four levels of N (0, 50, 100 and 150 kg ha-1), three levels of P (0, 50 and 100 kg P2O5 ha-1) and five levels of K (0, 50, 100, 150 and 200 kg K20 ha-1) along with three levels of farmyard manure (0, 6.25 and 12.50 t ha-1) fitted in a response surface design. Using multiple regression model, the fertilizer adjustment equation for N at varying soil test values for available N for maximum tuber yield (t ha-1) of cassava in laterite soil was derived as FN = 136.6 - 0.2 SN where FN is fertilizer N (kg ha-1) and SN is soil available N (kg ha-1). The equation becomes FN = 136.6 - 0.2 SN - R for economic tuber production where R is the ratio of cost of one kg of fertilizer N to price of one kg of tuber. At varying soil test values for organic carbon% (OC) the above equations become FN = 226.13 - 378.13 OC for maximum tuber yield and FN = 226.13 - 378.13 OC - 1.25 R for economic tuber yield. The behaviour of fertilizer P and K was found to produce responses other than 'normal' and hence optimisation could not be done for fertilizer P and K for maximum and economic tuber yield at varying soil test values. The nutrient requirements of cassava var. M-4 were estimated to be 6.58, 2.37 and 6.28 kg N, P2O5 and K2O respectively to produce one ton of tuber. In the laterite soil, the efficiencies of contribution of nutrients from the soil for cassava were calculated as 40.17, 41. 3 3 and 48.60% N, P2O5 and K2O respectively. The fertilizer efficiencies were worked out as 54.38, 47 and 52.650% N, P2O5 and K2O respectively. The efficiencies of contribution of nutrients from farmyard manure were calculated as 78.24, 57.33 and 69.66%) N, P2O5 and K2O respectively. From the above basic data, fertilizer prescription equations for specific yield targets of cassava var. M-4 in the laterite soil were derived as given below. Without FYM FN = 12.10 T - 0.74 SN FP2O5 - 5.04 T - 2.02 SP FK2O = 11.93 T - 1.10 SK With FYM FN = 12.10 T - 0.74 SN - 1.44 ON F P2O5 - 5.04 T - 2.02 SP - 2.79 OP FK2O = 11.93 T - 1.10 SK - 1.58 OK where FN, F P2O5 and FK2O are fertilizer N, P2O5 and K2O respectively in kg ha-1, T is the target of tuber yield in t ha-1, SN, SP and SK are soil available N, P and K in kg ha-1 respectively and ON, OP and OK are quantities of N, P and K supplied through organic manure in kg ha-1 The technology verification trial was undertaken during June '96-March. '97 in the laterite soil in three farmers' fields in Thiruvananthapuram district and also in the Instructional Farm, Vellayani. The treatments consisted of Package of Practices recommendation for fertilizer, fertilizer recommendation by the Soil Testing Laboratory and fertilizer doses for the yield targets of 15, 20 and 25 t ha-1 along with a uniform dose of 6.25 t ha-1 of farmyard manure for all treatments. The fertilizer doses based on targeted yield equations recorded higher tuber yield and net income, benefit cost ratio and net returns per rupee invested over the fertilizer recommendation by the Soil Testing Laboratory and Package of Practices recommendation emphasising the need for site specific recommendation based on soil tests. The yield targets of 15 and 20 t ha-1 recorded more than cent per cent achievement and the yield target of 25 t ha-1 recorded about 90% achievement. Higher tuber yield, benefit cost ratio and net returns per rupee invested could be achieved for the yield target of 20 t ha-1. The fertilizer dose for the yield target of 15 t ha-1 recorded the highest returns per rupee invested on fertilizers. The study has revealed the superiority of fertilizer application based on targeted yield approach over the semi-quantitative approach employed in the soil testing laboratories and generalised state level Package of Practices recommendation for the crop. In this approach, the fertilizer dose can be adjusted in accordance with the specific objective and available resources of the farmer.
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    ThesisItemOpen Access
    Sturcture analysis and system dynamics of agroforestry home gardens of southern Kerala
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Jacob, John; KAU; Achuthan, Nair M
    A study entitled "Structure analysis and system dynamics of agroforestry home gardens of southern Kerala" was undertaken during the period from 1994 - 1997 in Thiruvananthapuram district of Kerala State. The study comprised of a detailed agroforestry systems inventory description survey of the home gardens in the district, investigations on the system dynamics of two home gardens of the district, laboratory experiments to assess the allelopathic tendencies of some commonly grown multipurpose tree species and linear programming to develop integrated homestead models. The results of the survey revealed that the size of an overwhelming number of holdings was small. The species diversity and average number of plants per home garden was considerably high. Tuber crops ranked first among the crops, followed by fruits, oilseeds, rubber, spices, vegetables, timber and fuel trees and fodder crops. The tree intensity was found to increase as the size of the holding decreased. The frequency of occurrence was highest for coconut, followed by jack, mango, moringa, guava, wild jack and tamarind and lowest for the nitrogen fixing trees. Differences between the agroecological zones of the district with respect to the predominance of crop categories and tree species were also observed. The home gardens presented a multi-tier canopy configuration. There was no specific planting pattern or arrangement. The system, as a whole, was found to be profitable. The two year long field investigation on the dynamics of home gardens revealed that the tree components contributed considerable amounts of nutrients by way of litterfall, stemflow and throughfall. Nutrient addition took place mainly through organic manures at both locations. Harvested biomass accounted for removal of large quantities of nutrients from the systems. Coconut accounted for maximum biomass production and nutrient removal at both sites. The physical, chemical and microbiological properties of the homestead soil were better than that of the control. The soil in the homestead had a lower bulk density, high water holding. capacity, porosity and moisture "Content. An enhanced soil organic carbon content, available N, P and K status were also observed in the home garden. The soil microbial population (bacteria, fungi, actinomycetes and phosphorus solubilizing bacteria) was comparatively higher in the home garden. Nutrient cycling, recycling of crop residues and addition of organic manures helped in improving and maintaining the soil physico-chemical and biological properties of the system in a sustainable manner. The presence of trees lowered the soil temperature in the homestead, whereas relative humidity was maintained at an optimum level when compared to open condition. The light intensities at the floor of all the trees studied were invariably less than that in the open. Both the home gardens were found to be profitable. The tree-crop-livestock integration was a special feature which increased income considerably. Allelopathic inhibition of germination and growth of rice was caused by leaf extracts of all the tree species. Germination of cowpea was inhibited by the leaf extracts of acacia, eucalyptus, casuarina, ailanthus, tamarind, portia and cashew. Growth of cowpea was suppressed by leaf extracts of all the tree species except jack. The powdered leaf litter of all the trees inhibited rice germination and growth. However, jack did not suppress radicle growth. Cowpea germination was inhibited by the powdered litter of all the trees except jack and mange. Cashew, casuarina and jack did not suppress plumule growth of cowpea. Radicle growth of cowpea was inhibited all tree species. The integrated model for the 0.50 ha home garden with 23 enterprises was found to generate a profit of Rs. 10354.21 with an investment of Rs. 3262.30. The coconut-based mixed fanning model developed for the 0.40 ha home garden with 35 enterprises provided a net profit of Rs. 32464.32 on investing Rs. 45000/-.
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    ThesisItemOpen Access
    Nutrient - moisture- light interactions in a coconut based homestead cropping system
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Ravindran, C S; KAU; Sreedharan, C
    Two field experiments were conducted at the Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, to study the performance of intercrops in a mature coconut garden. The study was conducted for two years from June 1992 to May 1994. In the first experiment, the effect of nutrients, moisture and light on the productivity of intercrops, uptake of nutrients, quality of produce, soil properties and economics were studied. The effect of five cropping systems with two doses of fertilizers along with a control were tried in Randomised Block Design with three replications. In the second experiment, the interspecific root competition was studied using the radiotracer technique. The absorption of 32P by component crops in mono and mixed crop situation were investigated. Plant characters such as height and leaf area of intercrops were not influenced by cropping systems and different doses of fertilizers applied to intercrops. The results show that cassava can be raised along with banana, elephant foot yam and vegetable cowpea successfully under the partial shade of coconut. Half the recommended dose of N and P and full dose of K was found sufficient to the intercrops grown in coconut garden. The total dry matter production of economic produce of intercrops was not varying much by cropping systems and fertilizer doses probably because of the substitution effect. The highest uptake of NPK by intercrops was recorded in cropping system, coconut+ cassava+ banana (C4) followed by coconut+ cassava+ banana+ elephant foot yam+ vegetable cowpea (C5). The soil moisture status was not altered by raising different intercrops in coconut garden. Cassava received only 75% of PAR in the cropping system compared to open and there was a corresponding decrease in tuber yield also. Highest net income was obtained from coconut+ cassava+ banana+ elephant foot yam+ vegetable cowpea cropping system. Radiotracer studies using 32P showed that, cassava can be raised as intercrop in coconut, without much competition for nutrients. Banana can be grown in association with coconut without any adverse effect on banana nutrition. Cassava+ banana, elephant foot yam+ banana and cassava+ elephant foot yam are ideal combinations of intercrops which can be raised in coconut garden without any competition for nutrients. From the results, it can be concluded that cassava, banana, elephant foot yam and vegetable cowpea can be raised successfully and economically as intercrops in mature coconut garden applying half the recommended dose of N and P and full dose of K without much competition for nutrients, moisture and light.
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    ThesisItemOpen Access
    Effect of weather on cocoa and improvement of bean size through seasonal crop orientation
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1997) Prameela, K P; KAU; Vikraman Nair, R
    With an objective of understanding the probable reasons for seasonal fluctuations in flowering and fruiting and also to orient the cocoa crop to a season favourable for bean size, a four year investigation was carried out at the College of Horticulture, Vellanikkara during 1993-96. The influence of weather variables on flowering was studied by correlating weekly flower production with weather parameters of previous one to twelve weeks. This was done using plants with and without fruit load. Flower production was also correlated with increase in fruit load of previous one to twelve weeks. The possible effects of soil moisture deficit and surplus on flowering was also studied. The influence of weather on fruiting was studied by correlating monthly pod yield with weather variables of previous one to seven months. The influence of fruit load on fruiting was also studied by correlating monthly pod yield with increase in fruit load of previous one to seven months. For crop orientation study two sets of plants were used, one as control and the other as treatment. The plants used as control were retained as such without disturbing pods. In the other set, defloration was done excepting during the period from April to July. The results revealed that maximum temperature and bright sunshine hours were positively correlated with flower production while rainfall, relative humidity and number of rainy days were negatively' correlated. However, summer rains had positive effect. Fruit load had negative influence on flowering. For pod production the seasonal difference was much pronounced. During monsoon season a comparatively dry condition with high temperature and low relative humidity caused high pod production after five to six months, while in a non-monsoon period production was favoured by high humidity and high rainfall. Pod load affected flower and fruit production adversely. Models were developed to predict flower and fruit production from weather variables and pod load. The crop orientation study showed that the crop could be oriented to the favourable season of October-November without affecting the total annual yield. However, during years of heavy incessant rains the practice may fail.