Biodiversity And Arthropod Abundance In Organic Semi Rice In Swamp Lowland in Palangka Raya City

Palangka Raya has the potential for swamp lowland to be used for rice farming. For this purpose, knowledge of arthropod biodiversity is required. The study aims to determine the biodiversity and abundance of arthropods and arthropods dominant in semi-organic rice plantations in swamp lowlands. The study was conducted from September to November 2019 in Palangka Raya City. The study was carried out on 1.148m2 farmer's paddy fields. The land is divided into three trial plots, each measuring 28x13 m2. Observations were made at the age of 8-15 WAP. Samples were taken using a net trap (Sweep net). Arthropod biodiversity was analyzed using the Shannon-Weaver diversity index (H'). The results showed that in the semi-organic rice ecosystem were obtained 10 orders, 58 families with a total of 8973 individuals, consisting of pests 92.61%, predators 6.59%, parasitoids 0.28%, pollinators 0.06%, Detrivore 0.35%, and 0.07% neutral insects. Diversity index (H') is low to moderate (0.10-2.19), dominance index (C) is in the low to high (0.18-0.97); Evenness index shows that the community is depressed until unstable (0.04-0.67); and The abundance index on the criteria of less to very much (8.96-25.03). The dominant arthropods are dominated by the Rice bug (Leptocorisa acuta).

In Vitro Evaluation of Herbicides on Beneficial and Pathogenic Microorganisms

An experiment was conducted in the laboratory to evaluate the effect of herbicides on beneficial and pathogenic microorganisms. Eighteen treatments included six herbicides at three different doses viz., cyhalofop-butyl (80, 160 and 240 ppm), cyhalofop-butyl + penoxsulam (150, 300 and 450 ppm), bispyribac-sodium (25, 50 and 75 ppm), fenoxaprop-p-ethyl (60, 12 and 180 ppm), carfentrazone-ethyl (20, 40 and 60 ppm) and chlorimuron-ethyl + metsulfuron-methyl (4, 8 and 12 ppm) evaluated on beneficial microbial bioagents (Trichoderma viride and Pseudomonas fluorescens) and pathogenic microorganisms (Rhizoctonia solani, Pyricularia oryzae and Xanthomonas oryzae pv. oryzae). Results revealed that bispyribac-sodium and cyhalofop-butyl + penoxsulam had greatest inhibitory effect on pathogenic microorganisms Rhizoctonia solani (47.76 and 54.40%) and Pyricularia oryzae (49.07 and 61.12%), but showed no effect on Xanthomonasoryzaepv. oryzae, and were less harmful to biocontrol agents Trichoderma viride and Pseudomonas fluorescens at recommended doses, which were effective in control of broad spectrum of weed flora in rice ecosystem.

Impact of Organic and Inorganic Sources of Nutrients on Root Architecture, Soil Microbial Biomass and Yield on Low Land Rice Ecosystem

To study the impact of vermicompost, arbuscular mycorrhizae and FYM application on the rice ecosystem at low land, a field experiment was conducted with rice CO(R) 51 at the Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University in Coimbatore during the winter of 2020. The experiment was framed in Randomized Block Design comprising of 8 treatments viz., Recommended Dose of Fertilizer Soil Test Crop Response approach (T1), RDF 75 % + Farm Yard Manure @ 12.5 t ha-1 (T2), T2 + Seed treatment with Azospirillum and Phosphobacteria + Soil application of AM fungi (T3), RDF 75 % + Vermicompost @ 5 t ha-1 (T4), T4 + Seed treatment with Azospirillum and Phosphobacteria + Soil application of AM fungi (T5), FYM @ 12.5 t ha-1 + Seed treatment with Azospirillum and Phosphobacteria + Soil application of AM fungi (T6), Vermicompost @ 5 t ha-1+ Seed treatment with Azospirillum and Phosphobacteria + Soil application of AM fungi (T7) and Absolute control (T8) and replicated thrice. The maximum microbial population were registered in the plots that received integrated nutrient application of RDF 75 % STCR approach + Vermicompost 5 t ha-1 + seed treatment with Azospirillum and Phosphobacteria + Soil application of AM fungi. Rice root architecture has changed significantly as a result of mycorrhizal inoculation. Mycorrhizal rice plants have more root volume, length, and spread than plants without mycorrhizae. Nutrient retention and availability influenced the presence of microbial-mediated metabolic activities and nutrient transformations during crop growth. Bacteria, fungus, and actinomycetes became less abundant as the crop reached harvest. The population density of mycorrhizospheres that utilize both organic and inorganic fertilizers is higher. The treatments that received Vermicompost or FYM with Vesicular Arbuscular Mycorrhizae and Nitrogen, Phosphorous & Potassium fertilizers obtained the highest yields of rice grain and straw (6740 and 7840 kg ha-1) respectively, and it was clear that the combination of Vermicompost or FYM, VAM and along with NPK fertilizers produced significantly higher yields than their individual applications and absolute control.

Cadmium Speciation Distribution Responses to Soil Properties and Soil Microbes of Plow Layer and Plow Pan Soils in Cadmium-Contaminated Paddy Fields

Cadmium (Cd) speciation ratio in arable land determines the Cd exposure risk and Cd uptake in crops. However, the driving mechanisms of Cd speciation change on the vertical scale of paddy fields remain poorly understood. In this study, the effects of plow layer and plow pan on Cd speciation distribution were investigated in a long-term Cd-contaminated rice ecosystem. The Cd accumulative effect within rice grain was enhanced with high levels of activated Cd speciation ratios in soils. Activated Cd speciation ratios were higher in plow layer soils, while stabilized Cd speciation ratios were elevated in plow pan soils. Soil physicochemical properties and soil microbes synergistically affected the Cd speciation changes in different ways between the two soil layers. Soil pH and organic elements in plow layer environment directly hindered the transformation of stabilized Cd speciation, while in plow pan environment, soil pH and organic elements indirectly decreased activated Cd speciation ratios and resulted in the accumulation of stabilized Cd speciation via regulating the predominant bacterial taxa. This study will improve our understanding of how soil environments regulate Cd speciation distributions in rice ecosystems and help to seek effective remediation methods of Cd-contaminated paddy fields to reduce the Cd accumulation in rice.

Retrospection of Outbreaks of Spodoptera mauritia Boisduval in NER India: The Solution Lies in Ecological Engineering, Not in Insecticides

Rice cultivation in North East India is organic by tradition; however, the recent outbreaks of the rice-swarming caterpillar, Spodoptera mauritia Boisduval, have compelled rice-farmers to use synthetic insecticides. The outbreak in 2016 affected more than 56,768 ha of winter rice in 28 districts of Assam. About 25,545–42,576 L insecticide was applied in the state to combat the outbreak. This is one of the highest insecticide loads ever to be added to the rice ecosystem of Assam. Such a load, if added repeatedly with the reoccurrence of outbreaks, may affect the innate resilience of the rice ecosystem in the long run. In this paper, the outbreak of RSC has been analysed from an ecological perspective in order to replace the existing policy of exclusive dependence on insecticide. The review will help the researchers, extension workers and policy makers of the rice producing countries, more specifically in Asian countries, which together account for more than 91% of the world’s rice production.

Comparative efficacies of insecticides and botanicals against rice gall midge, Orseolia oryzae (Wood-Mason) and their effect on the parasitoid Platygaster oryzae in rice ecosystem of Odisha, India

A field experiment was carried out to determine the comparative efficacy of newer insecticides with botanical insecticides, viz., Chlorantraniliprole 0.4G @ 10 kg ha-1, Fipronil 5 SC @ 1500 ml ha-1, Acephate 95 SG @ 750 g ha-1, Lambda cyhalothrin 4.9 CS @ 550 ml ha-1, Thiamethoxam 25 WG @ 150 g ha-1 @ Carbofuran 3 CG @ 30 kg ha-1, Carbosulfan 25 EC @ 875 ml ha-1, Cedarwood oil @ 1000 ml ha-1, Azadirachtin 0.03 EC @ 2500 ml ha-1, applied at 20 and 35 DAT, against rice gall midge, Orseolia oryzae (Wood-Mason) in rice during kharif, 2019 and 2020. All the treatments were effective for gall midge. Lambda cyhalothrin 4.9 CS @ 550 ml ha-1 was significantly superior (>80% reduction over control) for gall midge management and grain yield was 4.75 t ha-1. Both botanical and untreated plots had more number of parasitized gall midge (40- 53.3%) than other chemical treated plots.

Degradation of Pyrazosulfuron Ethyl in Rice Ecosystem by Aspergillus terreus

Investigation on the degradation of pyrazosulfuron ethyl by Aspergillus terreus in the rice ecosystem was conducted at the Department of Biochemistry, UBKV, Pundibari Coochbehar, West Bengal, India. The soil was collected from the paddy field to isolate fungal inoculums. Results revealed that Aspergillus terreus can survive in minimal broth containing pyrazosulfuron ethyl at 1000 ppm and degrades through two major pathways, first involves the cleaves of sulfonylurea bridge resulting in the formation of two major metabolites viz., 2-amino-4, 6 –dimethoxyprimidine, 5-aminosulfonyl-1-methyl-pyrazole-4-carboxylic ethyl ester and, second was the cleavage of sulfonyl amide linkage which forms the metabolite viz; 1 methyl pyrazole-4-carboxylic acid ethyl ester,1 methyl pyrazole -4-carboxylic acid, 5-carbamoyl -1-methyl pyrazole -4-carboxylic acid ethyl-ester. The enzyme involved in these transformations can be utilized to decontaminate soil and water from Pyrazosulfuron ethyl residue. Even, the gene responsible for the production of these useful enzymes can be exploited for future research.

Management of Rice Blast (Magnaporthe Oryzae B. Couch) Using Bioagents and Fungicides Under Hill Rice Ecosystem of Uttarakhand State in India

A field study was conducted during Kharif-2015 and 2016 on management of leaf and neck blast disease of rice caused by Magnaporthe oryzae under hill rice ecosystem. Different treatments including biological control agents like Trichoderma sp. and Pseudomonas sp. and chemical fungicides like tricyclozole, azoxystrobin and carbendazim were used at different growth stages of rice. Among the treatments, tricyclozole @ 0.06% was highly effective followed by azoxystrobin @ 0.1% with application immediately after appearance of disease. Trichoderma and Pseudomonas were not effective in reducing the disease pressure. Bangladesh J. Bot. 50(3): 713-716, 2021 (September)