Ph.D

A study entitled “Magnetised water for enhancing herbicide and nutrient use efficiency in upland rice (Oryzasativa L.)” was conducted at Department of Agronomy, College of Agriculture, Vellayani during 2019-2024. The objectives of the study were to identify the strength of magnetised water for irrigation in upland rice, to study the effect of magnetised water on growth and yield of upland rice under different herbicide doses, to assess the nitrogen use efficiency, to find the suitable method of magnetised irrigation for rice and to work out the economics. The study comprised two experiments, Experiment I: Influence of magnetised water, humic acid and herbicide for growth and yield of upland rice, and Experiment II: Influence of magnetised water on growth and yield of upland rice under different herbicide doses and methods of irrigation, respectively. The experiments were carried out at Instructional Farm, Vellayani and the variety used was Prathyasa. Experiment I was conducted during January, 2021- April, 2021 and the design used was Randomised Block Design (RBD) with (2x3x2)+1 treatments replicated thrice. The treatments comprised combinations of magnetic strength of water (m1: 1000 G, and m2: 2000 G), application techniques of humic acid (a1: soil application, a2: foliar spray, and a3: soil + foliar application) and herbicide application (h1: bispyribac sodium @ 25g ha-1 at 15-20 DAS fb fenoxaprop ethyl @ 60g ha-1 at 35-40 DAS, h2: bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS), compared against a control (POP recommendations with two hand-weedings at 15 and 30 DAS). The growth parameters of the upland rice such as plant height, number of tillers m-2, leaf area index and dry matter production were significantly higher for the magnetic strength of 2000 G (m2) when compared to 1000 G. Among the different application techniques of humic acid treatments, the soil + foliar application of humic acid (a3) was observed to produce significantly taller plants, higher number of tillers m-2, leaf area index and dry matter production than the foliar spray of humic acid (a2) and soil application of humic acid (a1). The perusal of data showed that growth parameters weresuperior for the treatment, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2) over bispyribac sodium @ 25g ha-1 at 15-20 DAS fb fenoxaprop ethyl @ 60g ha-1 at 35-40 DAS (h1). The interactive effect of the treatments on the growth parameters revealed that the treatment combination of application of magnetic strength at 2000 G, soil + foliar application of humic acid and herbicide application of bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (m2a3h2) was statistically superior to other treatments. The control (c) treatment exhibited the lowest performance among all the treatments for the growth parameters. When compared to the other treatments, the treatment combination m2a3h2 recorded improved yield attributes and yield. The highest grain yield (3.40 t ha-1), straw yield (5.50 t ha-1) and harvest index (38.10%) were noted for m2. Among the application techniques of humic acid, a3 recorded the highest grain yield (3.26 t ha-1) and straw yield (5.51 t ha-1). The highest grain yield (3.08 t ha-1), straw yield (5.21 t ha-1) and harvest index (36.96%) were noted for the application of bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2). The treatment combination m2a3h2 recorded the highest grain yield (3.92 t ha-1), straw yield (5.98 t ha-1) and harvest index (38.72%) while the lowest grain yield (2.40 t ha-1) and straw yield (3.19 t ha-1) were recorded for the control. The treatments had significant influence on root parameters. The root depth, root volume and root weight were the highest for 2000 G (m2), soil + foliar application of humic acid (a3) and the herbicide treatment, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2) and the treatment combination, m2a3h2 . Significantly higher soil moisture content at 15 cm and 30 cm depth, crop water use efficiency (WUE), field WUE and water productivity were also recorded with 2000 G magnetic strength (m2), soil + foliar application of humic acid (a3) and the herbicide treatment, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2) and the treatment combination, m2a3h2. The available NPK and micronutrients after the harvest were found to be higherthan the initial content for the treatment combination, m2a3h2. The treatment combination, m2a3h2 also recorded the highest agronomic efficiency. The physiological efficiency was the highest for m2a3h2 which was statistically on par with m2a2h2. Weed flora observed in the field includes grasses such as Echinochloacolona, Eleusineindica, Digitariaciliaris, Setariabarbata, Brachiariamutica, Dactylocteniumaegyptium, broad leaf weeds such as Phyllanthusniruri, Eclipta alba, Alternantherasessilis, Hemidesmusindicus, Commelinabenghalensis, Portulacaolerace, Cleome gynandra, Mimosa pudica and sedge such as Cyperusrotundus. The application of 2000 G (m2), soil + foliar application of humic acid (a3) and the herbicide treatment, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2) and the treatment combination, m2a3h2 recorded the highest weed control efficiency and the lowest weed index values compared to the other treatments. The highest gross income, net income and BC ratio were recorded for 2000 G (m2), soil + foliar application of humic acid (a3) and the herbicide treatment, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS (h2). The treatment combination, m2a3h2 proved superior with the highest gross income, net income and BC ratio. Hence, irrigation with magnetised water of 2000 G (m2), soil + foliar application of humic acid (a3), and herbicide combination h2 (bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS) were selected for the conduct of Experiment II. Experiment II was conducted during January, 2022-April, 2022 and was laid out in split plot design with three main plot treatments and two subplot treatments in five replications. The treatments included i1: sprinkler irrigation i2: rain hose irrigation and i3: control (hose irrigation) as mainplot treatments and d1: 100% recommended dose of herbicide and d2: 75% recommended dose of herbicide as subplot treatments. The methods of irrigation and different doses of herbicides had significant effect on the growth and growth attributes, and yield attributes and yield of upland rice. Amongthe methods of irrigation, sprinkler irrigation (i1) resulted in superior growth parameters, grain yield, straw yield and harvest index, followed by control (i3). 100% recommended dose of herbicide (d1) proved superior with significantly higher growth and yield parameters. The treatment combination, i1d1 recorded the tallest plants, and the highest dry matter production, leaf area index, number of tillers m-2 and yield attributes such as number of panicles m-2, panicle weight, and percentage of filled grains panicle-1, compared to other treatments. The treatment combination i1d1 recorded the highest soil moisture content at 15 cm and 30 cm depth, field WUE, crop WUE and water productivity. Root parameters viz., root depth, root volume and root weight were observed to be superior for sprinkler irrigation (i1), 100% recommended dose of herbicide (d1) and the treatment combination, i1d1. Post-harvest soil analysis revealed that organic carbon, available NPK and micronutrients were higher for the treatment combination, i1d1 compared to the other treatments. The highest weed control efficiency and the lowest weed index were achieved with sprinkler irrigation (i1), application of 100% recommended dose of herbicide (d1) and the treatment combination, i1d1. Sprinkler irrigation (i1) recorded the highest gross income (₹ 147689 ha-1), net income (₹ 63432 ha-1) and BC ratio (1.75). 100% recommended dose of herbicide (d1) was observed to obtain significantly higher gross income (₹ 151546 ha-1), net income (₹ 68872 ha-1) and BC ratio (1.83) compared to d2. The treatment combination, i1d1 recorded the highest gross income (₹ 169730 ha-1), net income (₹ 85437 ha-1) and BC ratio (2.01) among all the treatments while the lowest was recorded for i2d2. The results revealed that the combination of sprinkler irrigation and 100% recommended dose of herbicide is a better combination for high yield and net returns in upland rice. From the results of the study, it could be concluded that a higher yield and BC ratio for upland rice could be obtained under combination of sprinkler irrigation with magnetised water of 2000 G, soil + foliar application of humic acid along with recommended dose of fertiliser (RDF), and 100% recommended dose of herbicide combination, bispyribac sodium @ 25g ha-1 at 15-20 DAS fb cyhalofop butyl @ 80g ha-1 at 35-40 DAS.