Management of Rhizoctonia blight of groundnut using antagonistic effects of bioagents and organic amendments

Rhizoctonia blight disease caused by Rhizoctonia solani in groundnut crop is one of the most devastating diseases occurring worldwide. The disease affects the morphological and physiological parameters of the crop leading to reduction in pod yield as well as oil yield. The pathogen was isolated locally and identified as Rhizoctonia solani based on molecular characterization. The efficacy of different bioagents in reducing the radial growth of pathogen was tested in vitro and highest mycelia growth inhibition was recorded by Trichoderma asperellum (89.07 %). Among the fungicides tested, 100 % mycelial growth inhibition was observed by use of Carbendazim 50 WP, Tebuconazole 25.9 % EC, Hexaconazole 5 % suspension concentrate (SC) and Tebuconazole 50 % + Trifloxystrobin 25 % water-dispersible granule (WG). Among different organic substances tested in vitro, neem seed cake achieved maximum mycelial growth inhibition of 50.74 % and 54.08 % at 10 % and 20 % concentrations respectively. In the field experiment, treatment with application of neem seed cake to the soil at 500 kg/ha + application of mustard seed cake to the soil at 500 kg/ha + treatment of seeds with Tebuconazole at 1.5 g/kg of seed + treatment of seeds with T. asperellum at 10 g/kg of seed was found to be the best in enhancing plant health, growth promotion and oil yield. The combined treatment of bioagent, fungicide and organic amendment recorded maximum number of branches (14.00), number of leaves (668.33), plant dry weight (64.17 g), 100 pod weight (65.00 g) and oil yield (47.33 %) compared to the control and other treatments along with reduction of the disease (59.61 %). In the physiological parameters study, the same treatment also recorded maximum pigment contents viz. Chlorophyll a (1.843 mg/g), Chlorophyll b (0.555 mg/g), total chlorophyll (2.397 mg/g) and carotenoid content (0.084 mg/g) but with minimum phenol content (1.693 mg/g). Thus, it can be concluded that integration of selective inputs in the combined treatment of Neem seed cake, Mustard seed cake, Tebuconazole and T. asperellum could enhance the plant health, morphological growth and physiological parameters and increased the oil yield in groundnut along with reduction of the disease

Distributed Resource Allocation with Local Information

Making distributed decisions based on incomplete information is inevitable in dynamic wireless networks due to a multitude of constraints. We study the effects of incomplete information on system performance in two parts. We first analyze the effect of incomplete topology information on network capacity and then the effect of partial traffic information on the capacity of a two-flow interference network. In the first part of the thesis, we study the effect of local topology information based resource allocation on the number of conflicts (called defects) produced in the network. First we show its equivalence to sum rate maximization of the network. Then we prove the non-existence of an universal local coloring protocol that can produce defect-free coloring. Next we find the optimal protocol with no information and a local coloring protocol for path graphs that can achieve Nash equilibrium. We develop a general framework to analyze any local coloring protocol based on a randomized starting point that can be applied to any graph. Finally we develop a graph decomposition method to apply it to any graph with non-overlapping cliques and cycles. In the second part of the thesis, we study a two-user cognitive channel, where the primary flow is sporadic, cannot be re-designed and operating below its link capacity. To study the impact of primary traffic uncertainty, we propose a block activity model that captures the random on-off periods of primary's transmissions. Each block in the model can be split into parallel Gaussian-mixture channels, such that each channel resembles a multiple user channel from the point of view of the secondary user. The secondary senses the current state of the primary at the start of each block. We show that the optimal power transmitted depends on the sensed state and the optimal power profile is either growing or decaying in power as a function of time. We show that such a scheme achieves capacity when there is no noise in the sensing. The optimal transmission for the secondary performs rate splitting and follows a layered water-filling power allocation for each parallel channel to achieve capacity

Bounds and protocols for a two-way multiple node channel

Often in multiuser wireless systems like cellular networks, data is present in both directions (uplink and downlink). One way to formulate protocols for such networks, is to design the uplink and downlink independently. But such a design ignores the two-way nature of data. We show that by jointly designing the uplink and downlink, we get rate gains as long as there is data in both the directions. We make a distinction between data being two-way and the channel being two-way and show that for the case where only the channel is two-way, a disjoint design is optimal. The rate gains can be attributed to the inherent feedback in two-way schemes which enables cooperation in all topologies (including hidden node topologies). Furthermore, in near-far situations, the weak user gains appreciably from such cooperation. Finally we demonstrate that several well known inner bounds can be derived as special cases of our rate region