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2015 - 20193
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Author: Arya, S R × Start date: 2015 ×
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    ThesisItemOpen Access
    Effect of foliar application of selected micronutrients and growth regulators on tuber development , yield and fortification status of sweet potato (Ipomoea batatas L.).
    (Department of Plant Physiology , College of Agriculture,Vellayani, 2019) Arya, S R; KAU; Viji, M M
    A field experiment entitled “ Effect of foliar application of selected micro nutrients and growth regulators on tuber development, yield and fortification status of sweet potato (Ipomoea batatas L.)” was conducted at the Instructional farm, College of Agriculture, Vellayani during the period 2017-2019 with an objective to enhance the qualitative and quantitative attributes in sweet potato (Ipomoea batatas L.). Foliar application of selected micronutrients and growth regulators were carried out to study their effect on growth, development and changes in fortification status of sweet potato tubers and leaves. The sweet potato variety used for the experiment was Bhu Krishna. The technical programme consisted of 17 treatments and 3 replications with the design simple RBD. The treatments were C1 : NPK (as per POP) , C2 : NPK (as per POP) with water spray, T1 : C1+ FN (MN mixture( * ) 0.01% each , T2 : C1+ FN (MN mixture( * ) 0.05% each , T3 : C1+ FN (MN mixture( * ) 0.1% each , T4 : T1+ Ethrel 250 ppm , T5 : T1+ Ethrel 500 ppm , T6 : T1+ CCC 250 ppm , T7 : T1+ CCC 500 ppm , T8 : T2+ Ethrel 250 ppm , T9 : T2+ Ethrel 500 ppm , T10: T2+ CCC 250 ppm , T11: T2+ CCC 500 ppm, T12: T3+ Ethrel 250 ppm , T13: T3+ Ethrel 500 ppm , T14: T3+ CCC 250 ppm and T15: T3+ CCC 500 ppm [*MN mixture (Zn+Fe+B+Mn)]. Except C1, for all other treatments foliar sprays were given 3 times ie. at 30 days interval(30 DI). All the biometric and physiological parameters were taken at 25th,50th,75th and 100th days after planting and the quality parameters were taken at harvest. The results revealed that the micronutrients and growth regulators had significant influence on most of the biometric parameters, physiological parameters as well as quality parameters. Tuber characters such as tuber length, tuber diameter, tuber weight and tuber yield were found to be best in plants under the treatment T15 (T3+ CCC 500 ppm at 30DI) and it was on par with T13(T3+Ethrel 500ppm). Branch length (155.50cm), shoot weight (612 g) and specific leaf area (389.44 cm2 g-1) were found to be best in plants under the treatment T3(C1+ FN (MN mixture( * ) 0.1% each at 30DI). Number of leaves also were found to be higher in T3 (91.33) and it was on par with T2, T13 and T15. Cycocel and ethrel are growth retardants and they were found to have dwarfing effect on plants and hence shoot length and shoot weight did not increase in the treatments, T15(T3+ CCC 500at 30DI) and T13(T3+ Ethrel 500 ppm at 30DI) and on the other hand the number of leaves got positively influenced in both these treatments T15 and T13. Except transpiration rate all physiological parameters viz., total chlorophyll content (2.25 mg g-1), caroteinoid content (0.87mg g-1), stomatal conductance (131.33 mmole H2O m-2 s-1), photosynthetic rate (4.49 µmole CO2 m-2 s-1) and water use efficiency (5.35 mmol CO2 mol-1 H2O) were found to be best in plants under the treatment T15 (T3+ CCC 500 ppm) and T13 was on par with T15 in all these physiological parameters studied. Mineral constituents; N (0.614 %), P (0.056%), K (0.489%),Fe (16.30 mg kg-1), Zn (15.07 mg kg-1), Mn (7.37 mg kg-1) and B (1.27 mg kg-1) as well as other quality parameters like total phenol (13.33mg g-1), total sugar (34.48 mg g-1) and protein content (38.40mg g-1) were found to be higher in tubers under the treatment T15 (T3+ CCC 500 ppm) followed by treatment T13 which is considered as the second best treatment with respect to mineral content in tubers. Overall, the combined treatments of micronutrients along with growth regulators were found most effective in influencing quality parameters. Treatment T15 (ie.,NPK as per POP along with foliar nutrition of micronutreint mixture (Fe+Zn+Mn+B @ 0.1% each ) + cycocel (500ppm) at 30 days interval ) was found to be the best in terms of improving both the quantitative and qualitative attributes in sweet potato. Hence it is concluded that the treatment T15 improved the growth and development of plants, physiological parameters of leaves, tuber yield as well as fortification status of sweet potato tubers. Thus this study helped in identifying the best treatment combination of micronutrients and growth regulators for improving growth, development, yield and fortification status in sweet potato.
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    ThesisItemOpen Access
    Bioefficacy and soil health impact of flucetosulfuron in wet seeded rice (Oryza sativa L.)
    (Department of Agronomy, College of Agriculture, Vellayani, 2018) Arya, S R; KAU; Elizabeth, K Syriac
    The investigation entitled "Bioefficacy and soil health impact of flucetosulfuron in wet seeded rice (Oryza sativa L.) was carried out at College of Agriculture, Vellayani, Thiruvananthapuram during the period of 2015-2018. The objectives were to evaluate the bioefficacy of flucetosulfuron in wet seeded rice; to assess its impact on soil health by determining the microbial count, earthworm population, enzyme status and herbicide residue in soil through bioassay using indicator plant as well as to assess the weed seed bank. It was also envisaged to study the in vitro sensitivity of biofertilizer organisms and biocontrol agents to flucetosulfuron. Field experiment was conducted during the I and II crop seasons of 2016- ’17, in a farmer’s field in Kalliyoor Panchayat, Nemom block, Thiruvananthapuram district, Kerala, with 12 treatments replicated thrice in Randomized Block Design. The treatments were: T1 : Flucetosulfuron @ 20 g ha-1 at 2-3 DAS, T2 : Flucetosulfuron @ 25 g ha-1 at 2-3 DAS, T3 : Flucetosulfuron @ 30 g ha-1 at 2-3 DAS, T4 : Flucetosulfuron @ 20 g ha-1 at 10-12 DAS, T5 : Flucetosulfuron @ 25 g ha-1 at 10-12 DAS, T6 : Flucetosulfuron @ 30 g ha-1 at 10-12 DAS, T7 : Flucetosulfuron @ 20 g ha-1 at 18-20 DAS , T8 : Flucetosulfuron @ 25 g ha-1 at 18- 20 DAS , T9 : Flucetosulfuron @ 30 g ha-1 at18-20 DAS, T10: Bispyribac sodium @ 25 g ha-1 at 15 DAS, T11: Hand weeding at 20 and 40 DAS and T12 : Weedy check. The short duration variety Kanchana was used for the trial. The weed flora in the experimental field comprised of four species of grasses, six species of broad leaved weeds and three species of sedges. Based on density and dry weight, sedges were the predominant group in the experimental field followed by broad leaved weeds and grasses. Application of flucetosulfuron @ 20, 25 and 30g ha-1 at 10-12 and 18-20 DAS (T4, T5, T6, T7, T8 and T9) recorded lower total weed density, total weed dry weight and nutrient removal by weeds and higher total weed control efficiency and were on par with the hand weeding treatment (T11). Yield reduction due to weeds was found to be 52.33 and 55.61 per cent during the I and II crop seasons respectively. The highest grain yield was recorded by the application of flucetosulfuron @ 25 g ha-1 at 10-12 DAS (T5) and flucetosulfuron @ 20 g ha-1 at 10-12 DAS (T4) during the first and second crop seasons respectively. The same trend was observed in the case of dry matter production also. Pooled analysis of the grain yield for the two seasons indicated the superiority of T5 which recorded the highest grain yield of 8.33 t ha-1. This treatment was on par with the other levels of flucetosulfuron viz., 20 and 30 g ha-1 at 10-12 DAS (T4 and T6) and hand weeding treatment (T11). Higher yield attributes, harvest index and nutrient uptake were also recorded for these treatments. However, net income and B:C ratio were significantly lower for hand weeding treatment. Herbicide application did not cause any significant inhibitory effect on the earthworm population and spider count. Application of herbicides increased the microbial population in herbicide treated plots. Flucetosulfuron, at the tested doses (20, 25 and 30 g ha-1) and time of application (2-3, 10-12 and 18-20 DAS), did not show any adverse impact on the activity of soil enzymes (dehydrogenase, acid phosphatase and urease) and soil organic carbon status. To identify the most suitable indicator plant for assessing flucetosulfuron residue in soil, four separate pot culture experiments were conducted using barnyard millet, cucumber, sunflower and maize. Sunflower was identified as the most sensitive indicator plant and shoot length of sunflower was adjudged as the best parameter to assess the flucetosulfuron residue in soil. Bioassay after each field experiment using sunflower revealed that there was no residual toxicity of flucetosulfuron in the post experiment soil. Pot culture experiments were carried out before and after each field experiment, to study the weed seed bank dynamics. Results revealed that non- herbicidal plots recorded higher weed count compared to herbicide applied plots. In all the herbicide treated plots, effective reduction in weed seed bank could be obtained irrespective of the dose of the herbicide. Regarding the time of application, application of flucetosulfuron at 10-12 and 18-20 DAS caused significant depletion of weed seed bank during both the seasons compared to its application at 2-3 DAS. In vitro sensitivity of biofertilizer organisms viz., Azospirillum lipoferum, Azotobacter chroococcum, Bacillus megaterium and Frateuria aurantia to flucetosulfuron indicated that growth of none of the organisms were significantly inhibited by the tested doses of flucetosulfuron. Similarly, in vitro sensitivity to biocontrol agent Trichoderma viride revealed that, at all the tested concentrations of flucetosulfuron, it showed a colony diameter of 9 mm uniformly with zero per cent inhibition indicating the compatibility of the herbicide. The compatibility studies with Pseudomonas fluorescens also revealed the safety of the herbicide. The present study revealed that application of flucetosulfuron @ 20, 25 and 30 g ha-1 at 10-12 DAS was very effective in controlling the weeds and recorded significantly higher grain yield and monetary benefits in wet seeded rice. Application of flucetosulfuron @ 20, 25 and 30 g ha-1 at 2-3/10-12/18-20 DAS had no adverse impact on soil health and was found compatible with the tested biofertilizer organisms (Azospirillum lipoferum, Azotobacter chroococcum, Bacillus megaterium and Frateuria aurantia) and biocontrol agents (Trichoderma viride and Pseudomonas fluorescens).
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    ThesisItemOpen Access
    Herbicide based weed management for semi dry rice (Oryza sativa L.)
    (College of Agriculture, Vellayani, 2015) Arya, S R; KAU; Ameena, M
    An investigation entitled “Herbicide based weed management for semi dry rice (Oryza sativa L.)” was conducted during the period May to September 2014 at farmer’s field in Nemom block, Thiruvanthapuram. The main objectives of the study were to evaluate the weed control efficiency of new generation herbicides in semi dry rice, to assess their selectivity and influence on growth and yield, to work out the economics and to develop a weed management strategy for semi dry rice. The field experiment comprised of eleven treatments replicated thrice (Variety: Uma) was laid out in randomised block design. The treatments were T1: bensulfuronmethyl + pretilachlor @ 60 + 600 g a.i. ha-1 (pre - emergence), T2: T1 + hand weeding at 40 DAS, T3: T1 + azimsulfuron @ 30 g a.i. ha-1 (post emergence), T4: pyrazosulfuron ethyl @ 25 g a.i. ha-1 (pre - emergence), T5: T4 + hand weeding at 40 DAS, T6 : T4 + azimsulfuron @ 30 g a.i. ha-1 (post emergence), T7 : oxyfluorfen @ 0.15 kg a.i. ha-1 (pre - emergence), T8 : T7 + hand weeding at 40 DAS, T9 : T7 + azimsulfuron @ 30 g a.i. ha-1 (post emergence) and two controls: T10: hand weeding at 20 and 40 DAS and T11: weedy check. Result of the study revealed substantial reduction in weed population and biomass in all the herbicide treated plots compared to weedy check. Weed composition of the experimental field indicated the dominance of broad leaved weeds followed by sedges and grasses with considerable variation in weed flora during dry and flooded condition. Hand weeding at 20 and 40 DAS (T10) recorded lowest weed density, weed dry weight and highest weed control efficiency. Absolute frequency (Af) for all weed species throughout the crop growth stages was also lower under hand weeding while higher values of importance value (IV) and summed dominance ratio (SDR) for sedges and broad leaved weeds were recorded in weedy check (T11). Pre-emergent herbicide application followed by either hand weeding at 40 DAS (T2 and T5) or application of post emergent herbicides (T3 and T6) recorded higher weed control efficiency and lower nutrient removal in comparison with hand weeding twice (20 and 40 DAS). None of the herbicides produced any phytotoxic symptoms on rice plant. However, crop density and growth was lower at the initial stages in oxyfluorfen treated plots. This indicated that bensulfuron methyl + pretilachlor and pyrazosulfuron can be treated as safe pre-emergent herbicides for dry sown (semi dry) system of rice cultivation. Result of the study also indicated the safety of the herbicides on microbial activity as evidenced by the increase in soil dehydrogenase activity in herbicides applied plots. The yield attributes of rice viz., number of productive tillers m-2 and filled grains panicle-1 were significantly influenced by the weed management practices T2, T3, T5, T6 and T10. Grain yield (4817.67 kg ha-1) and straw yield (7969.33 kg ha-1) were significantly higher in T2 (bensulfuronmethyl + pretilachlor @ 60 + 600 g a.i. ha-1 + hand weeding at 40 DAS) and remained on par with T3, T5, T6 and T10. Yield loss due to weeds was found to be 52.22 per cent. The most economically viable weed management practice was T6 (bensulfuronmethyl + pretilachlor fb azimsulfuron) with a B: C ratio of 1.76 which was on par with T3 (1.75). Grain yield, net income and B: C ratio were significantly lower in weedy check. It can be concluded that the most effective weed management practice for semi dry rice is pre-emergence application of either bensulfuron methyl + pretilachlor @ 60 + 600 g a.i. ha-1 or pyrazosulfuron ethyl @ 25 g a.i. ha-1 on the next day of sowing followed by post emergence application of azimsulfuron @ 30 g a.i. ha-1 at 25 DAS.