PG Thesis

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/2

Browse

Subject: search.filters.subject.sweet potato

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Performance and allelopathic effect of sweet potato in double cropped lowlands
    (Department of Agronomy, College of Agriculture, Vellayani, 2022-12-20) Arun Thazhath; Jacob John
    A study titled “Performance and allelopathic effect of sweet potato in double cropped lowlands”was conducted at College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana during the period from April 2020 to November 2020 with the objectives of evaluating the performance of sweet potato varieties in summer rice fallow, assessing their allelopathic effects on weeds and examining the residual effect on succeeding virippu rice crop in double cropped lowland rice based cropping system. The study comprised three experiments. Experiment-I was a laboratory bioassay, to assess the allelopathic effect of leaf leachates different varieties of sweet potato on rice var.Uma, laid out in completely randomized design (factorial CRD), with three replications. The two factors involved in the experiment were leaf leachate of different varieties and various concentrations. There were a total of 24 (Leaf leachate of 8 varieties) x (3 concentrations viz. 1: 5, 1:10 and 1:15 w/v) treatment combinations and one control (tap water). The varieties selected were Sree Kanaka, Sree Varun, Sree Arun, Sree Nandini, Sree Bhadra, Bhu Sona, Bhu Krishna and Kanjanghad. The parameters recordedwere germination percentage, days required for 50 per cent germination, germination index, plumule length, radicle length, response index, pH of leachates and phenol and tannin content of leachates. Experiment-II was a field experiment conducted by raising sweet potato varieties in double cropped lowland during the summer. Randomized block design (RBD) was adopted for this experiment with three replications. The treatments were the eight sweet potato varieties and one fallow treatment as control. Experiment-III was a field experiment aimed at examining the residual effect of sweet potato crop by raising rice crop in the same plots where experiment-II was conducted. Thus, the treatments of this experiment were same as that of experiment-II. Germination percentage was not significantly affected by the leaf leachates of different sweet potato varieties or the leachate concentration. The highest germination index was recorded in Sree Arun (1.87) and lowest in Bhu Krishna (1.59). Plumule length was maximum in treatment Sree Bhadra (4.6 cm) and lowest for Bhu Sona (3.93 87 cm). Control showed significantly greater plumule length (5.08 cm) than treatments. Maximum radicle length was observed in Sree Bhadra (8.93 cm) which was on par with Sree Kanaka and Sree Nandini. With respect to concentration of the leachates, radicle length was the greatest in 1:15 (w/v) (8.73 cm) and least in 1:5 (W/V) (8.14 cm). pH of all the leaf leachates were lower when compared to the control. Phenol content was the highest in leaf leachates of Bhu Krishna (2.34, 2.19 and 1.96 mg 100g1 at 1:5, 1:10 and 1:15 concentration levels respectively) followed by Bhu Sona. The maximum tannin content was observed in leaf leachate of Bhu Sona (80.40, 71.70, 63.57 mg 100g-1 at 1:5, 1:10 and 1:15 concentration levels respectively). Grass weeds were the most prevalent in the field. Among grasses, population of Leptochloa chinensis and Echinochloa crus-galli significantly differed among the treatments. The population of different species of broad-leaved weeds and sedges did not differ significantly among treatments. In case of grasses, the highest weed count was seen in the control (210.67) which was on par with Sree Bhadra and Bhu Sona. The lowest weed dry weight was in Sree Arun (9.37 g m-2 ) which was on par with Kanjanghad, Bhu Krishna, Sree Nandini and Sree Varun. The highest weed control efficiency was observed in Sree Arun (45.97 %) which was on par with Bhu Krishna (45.19 %). At 20 DAP, the dry matter production (DMP) was comparable among the sweet potato varieties. At 40 DAP, the highest dry matter production was observed in Sree Varun (35.97 g/plant) which was on par with Bhu Krishna and Sree Arun. At 60 DAP, maximum DMP was seen in Bhu Krishna (46.85 g/plant) and was on par with Sree Varun and Kanjanghad. At harvest, Bhu Krishna had maximum DMP (52.09 g/plant) and was on par with Sree Varun (50.13 g/plant). Crop growth rate (CGR), during the period of 40 to 60 DAP alone, was significantly higher in Bhu Krishna (4.57 g m-2 day-1 ) and it was on par with Kanjanghad (4.49 g m-2 day-1 ) and Sree Varun (3.63 g m-2 day-1 ). Relative growth rate (RGR), during the period of 40 DAP to 60 DAP alone, was highest in Kanjanghad (14.06 x 10-3 g g-1 day-1 ) and it was on par with Bhu Krishna (13.28 14.06 x 10-3 g g-1 day-1 ) and Sree Nandini (11.21 14.06 x 10-3 g g-1 day-1 ). At 40 DAP, the SPAD value was the highest for Sree Varun (39.07) which was on par with all treatments, except Sree Bhadra and Sree Arun. At 60 DAP, SPAD value 88 was the highest in Sree Nandini (40.03) which was on par with Kanjanghad, Bhu Krishna and Sree Varun. Post-harvest soil analysis revealed the lowest soil pH in control (5.25), Bhu Krishna, Sree Varun and Sree Kanaka all of which were on par. The highest organic carbon content was noticed in Sree Arun (1.36 %) which was commensurate with Bhu Krishna, Sree Nandini and Sree Varun. The highest available nitrogen content was observed in Bhu Sona (215.12 kg ha-1 ) which was similar to Kanjanghad, Bhu Krishna, Sree Bhadra and Sree Nandini. The highest available potassium content was observed in Bhu Sona (85.17 kg ha-1 ) and it was on par with control plot, Sree Bhadra, Sree Nandini and Sree Kanaka. Highest gross income, net income and benefit:cost ratio were obtained from Kanjanghad which was on par with Bhu Krishna and Sree Varun. Highest rice grain yield was obtained in the crop that followed Kanjanghad (2103.17 kg ha-1 ) which was on par with that which followed Bhu Krishna and Sree Arun. There was no significant difference in straw yield between treatments. Hence, from the experiments it can be concluded that Bhu Sona and Bhu Krishna varieties exerted a greater inhibitory allelopathic effect on rice seedling growth compared to other varieties. Among the varieties, Sree Arun (upto 64 %) and Bhu Krishna (upto 61 %) suppressed weed growth more with higher weed control efficiency. Evaluation of sweet potato varieties in summer fallows of double cropped lowland revealed that Bhu Krishna, Kanjanghad and Sree Varun performed better with respect to yield attributes, yield and economics. In the virippu rice crop raised to assess residual effect, higher yield was obtained the crop which succeeded Bhu Krishna, while the lowest yield was observed in crop that followed Bhu Sona.
  • No Thumbnail Available
    Item
    Partial substitution of potassium with sodium in sweet potato
    (Department of Agronomy, College of Agriculture, Vellayani, 1995) Joggy Mariam George; Chandrasekharan, P
    An investigation was carried out at Instructional Farm, College of Agriculture, Vellayani to study the effect of substituting potassium with sodium in varying levels in sweet potato. The levels of substitution consists of 0, 12.5, 25, 50 and 75 per cent, as potassium and sodium on equivalent basis. The trial was laid out in RBD with four replications. Partial substitution of potassium with sodium to the extent of 50 per cent increased the growth attributes like length of vine, number of branches plant -1 and LAI at all growth stages. Physiological parameters like TBR and CGR were increased due to the combined application of potassium and sodium on 50:50 ratio. Marketable tuber yield and yield attributes like number of tubers plant-1, length of tuber and girth of tuber were increased by the combined application of both the cations. Combined application of potassium and sodium increased the quality attributes of tubers like starch, protein and total sugar. Cooking qualities was also found to be better when potassium and sodium were applied together. Pest incidence was also reduced when both the cations were applied in 50:50 ratio. Combined application of K and Na produced maximum N, P and Na content in tubers whereas K content was maximum at zero per cent substitution. Uptake of nutrients (N, P, K and Na) were maximum at 50 per cent substitution. Soil properties like pH, Ec, water holding capacity, available potassium and sodium were not affected by treatments. Physiological efficiency of N, P and Na were found to be maximum at 0 per cent substitution whereas that of K was maximum at 75 per cent substitution. Agronomic efficiency and recovery fraction of N, P and Na was found to be increased in the presence of both cations. Fifty per cent substitution of potassium by sodium was more economic than the existing package of Practices Recommendation.
  • No Thumbnail Available
    Item
    Standardisation of agro-techniques for sweet potato variety sree nandini
    (Department of Agronomy, College of Agriculture, Vellayani, 1990) Sudhadevi, K C; Achuthan Nair, M
    With a view to standardise the agro-techniques for sweet potato var. Sree Nandini, a field experiment was conducted in the wetlands of the instructional Farm of College of Agriculture, Vellayani. The main objectives of this experiment was to work out the optimum dose and time of application of potassium and depth of planting for the sweet potato var. Sree Nandini. The experiment was laid out in split plot design with four replications. The main plot treatments included 3 levels of potassium (50 kg, 75 kg and 100 kg K2O/ha) and 2 depths of planting 95 cm and 10 cm) while the subplot treatments consisted of the different time of application of potassium (full basal, half basal + half topdressing, 1/3 basal + 2/3 top – dressing and 2/3 basal + 1/3 topdressing). An abstract of the results is given below : Among the vegetative growth characters, the length of vines was found to be maximum at the highest level of potassium while the number of branches and leaf area of index were not influenced by the levels of potassium. The drymatter production and tuber bulking rate were maximum when potassium was applied at 100 kg K2o/ha. The tuber number, length of tuber, girth of tuber and tuber yield were also maximum at the highest level of potassium. Among the quality attributes, starch content was maximum at the highest level of potassium and sugar content was maximum at the lowest level while the crude protein content was not affected by the different levels of potassium. The uptake of potassium and phosphorus were maximum at 100 kg K2o/ha. The highest available nitrogen and potassium content of the soil was also obtained at this level while available phosphorus content of the soil was not affected. As regards the time of application of potassium, application of potassium in two equal splits produced the longest vines while the number of branches and LAI were not affected. The parameters like drymatter production, tuber bulking rate, length and girth of tubers, tuber yield, starch content of tubers and uptake of potassium by plants were also maximum in this treatment while the vine yield, crude protein content of tubers and uptake of nitrogen and phosphorus by plants were not influenced by the time of application of potassium. The depth of planting had no significant influence on most of the parameters investigated like number of branches, LAI, drymatter production, tuber number, tuber yield, vine yield, quality attributes of tubers and uptake of nutrients by plants. However, deeper planting increased the length of vines while the size of tubers and tuber bulking rate decreased with deeper planting. Thus, it is revealed from the present study that the application of 100 kg K2o/ha in two equal split doses – half as basal and half as topdressing in combination with a planting depth of 5 cm is more profitable for the particular variety under the agro-climatic conditions prevailing in Thiruvananthapuram district.