Physiological and Agronomic Responses of Four Rice Varieties to Drought in the Rainforest

The present investigation tested the hypothesis that there would be variation in physiological responses to water deficit among rice varieties from different production ecologies, with contrasting tolerance to water deficit under repeated cycle of soil moisture deficit, at reproductive growth stage. A screen house and a field trial were conducted at International Institute of Tropical Agriculture, Ibadan and Ikenne (Latitude 6° 52' N, Longitude 3° 43' E) respectively. Both experiments had rice varieties (‘IR 64’, ‘WAB 56-104’, ‘IR 77298-1-2-B-10’ and ‘NERICA 4’) and stress status (stress and control) as treatment factor’s, arranged in a randomised complete block design with three replicates. In both trials, the physiological mechanism that underpins varietal differences with repeated cycles of water deficit at the reproductive growth stage was more balanced water status, improved foliar characters, efficient photosynthetic capacity and higher grain yield in comparatively drought tolerant upland rice varieties (‘NERICA 4’ and ‘WAB 56-104’), as opposed with the results for the drought susceptible cultivar ‘IR 64’. A converse pattern was observed on water stressed rice, despite fewer cycles of water deficit on the field. The results could have suggested that the initiation of water deficit is the rate limiting step rather than its intensity at the reproductive growth stage

Availability and dynamics of organic carbon and nitrogen indices in some soils amended with animal manures and ashes

Abstract Purpose The study evaluated dried manures and manure ashes as alternative products from animal manures, and determined the dynamics of soil nitrogen availability indices and organic carbon release in some soils amended with dried manures and ashes under laboratory incubation, screen-house and field experiments. Methods Cattle, goat and poultry manures were collected and air dried to produce dried manures after which part of the dried manures were burnt in open space at a temperature range of 320–450 °C to produce manure ashes. Treatments which were no amendment (control), dried manures of cattle, goat and poultry manure ashes of cattle, goat and poultry and NPK 15-15-15 at 120 kg N ha−1 were applied to soil. Samples were taken fortnightly after amendment incorporation in the incubation experiment; in screen-house experiment and field experiments, plant seeds were established after amendment incorporation; thereafter, soil samples were taken fortnightly. Soil samples were analyzed for soil organic carbon (SOC), NH4 +–N and NO3 −–N using a spectrophotometer. Results Incineration of manures increased pH, exchangeable cations and carbon, while nitrogen in manures ashes was comparable to nitrogen in dried manures. The application of manure ash increased SOC, NH4 +–N and NO3 −–N by 182, 102, 128% in incubation experiment while 64 and 628% increase in SOC and NH4 +–N was recorded in screen-house experiment, respectively, relative to the control. In the field experiment, a significant increase in NO3 −–N was recorded at the onset of incorporation; nitrification was more pronounced than ammonification under incubation and field conditions. Conclusion Dried manures are not superior to manure ashes and incorporation of manures ashes increased the SOC, NH4 +–N and NO3 −–N though changes with increasing weeks were erratic

Brain Gross Anatomy and Cerebellar Histology of the Cattle Egret (Bubulcus ibis)

The structural parts of brain are similar in all vertebrates, but they differ in their complexity and organization. The avian brain for instance, is organised differently compared to mammals, with variations existing in the relative size and location of their structures. The cattle egret (Bubulcus ibis) is a cosmopolitan avian species native to Africa. Despite their economic importance as excellent sentinels in assessing environmental pollutants, there is a dearth of information on their neuroanatomy. Hence, we here investigated their gross morphological features and morphometric parameters, and the cerebellar histology. Twelve transcardi-ally perfused juvenile cattle egrets were studied, with the body and brain weights and brain linear measurements considered. The brain weight constituted 0.46 % of the total body mass, with a strong positive correlation recorded between the body and brain weights (r = 0.9204). Morphologically, the brain was lissencephalic, with the corpus callosum absent and the olfactory bulbs rudimentary with no discernible division into the olfactory bulb, olfactory tract and olfactory lobe. We observed prominent sagittal eminence and vallecula telencephali, as well as an obvious fovea limbica on the dorsal and lateral surfaces of the cerebral hemispheres, respectively. The diencephalic structures were completely covered by telencephalon, with the pineal gland occupying the polygonal space between cerebrum, optic lobe and cerebellum. The mesencephalic tectum appeared as a large oval bilaterally bulging structure with prominent optic tracts and constituted the bulk of the midbrain. There was a dorsal extension of the fourth ventricle into the cerebellum known as the ventriculus cerebelli and the cerebellar histology presented a persistent external granular layering suggestive of a potential for adult neurogenesis. Our data has added relevant literature on the cattle egret brain and could prove useful in comparative, developmental and evolutionary avian neuroanatomy

Lead and lead isotopes as tracers of soil contamination in southwestern Nigeria

The association of soil Pb levels has received considerable attention in recent times in developing countries like Nigeria due to its human health and environmental effect. Unfortunately, the sources of the pollutant has not been resolved for environmental health interest. Therefore, the aim of this study is to trace the sources of Pb contamination using the isotopic composition of Pb in the soil. Thirty (30) soil samples were collected at 0-20 cm depth in 3 different land-use zones, industrial area (IDA, n=10), municipal solid waste facility (MSW, n=10), and traffic section (TRS, n=10). In addition, 3 rock (gneisses) and 3 blacksmith dust samples were collected in the study area for comparison. Properties of the soil such as physico-chemical parameters (pH, organic content, and soil texture) and mineralogical composition were determined to understand the distribution of Pb in the soil of the study area. Similarly, the samples were analyzed for their Pb concentrations and Pb isotopic compositions using inductively coupled plasma mass spectrometry. The soil pH, organic matter, and texture were slightly acidic (4.9-6.9), average organic content (7.9-19.1%), and sandy clay loam in nature, respectively. Therefore, the Pb distribution was enhanced by the physico-chemical parameters. However, the mineral constituent of the soil in order of their abundance include quartz, feldspars, illite-muscovite, kaolinite, Biotite, goethite, and hematite. Consequently, there is no Pb-rich primary mineral in the soil. The environmental assessment of Pb in the study area showed that all the zones were contaminated on the basis of the average contamination factor and geoaccumulation index values. Similarly, the ecological risk factor estimation of Pb showed that the three zones had moderate potential ecological risk factors (41-54). The isotopic compositions of 208Pb/207Pb, and 206Pb/207Pb of the contaminated soil were lower than the corresponding component in gneisses, while the composition of 208Pb/206Pb was higher than the gneisses. Furthermore, the standard plot of (208Pb/207Pb) vs (206Pb/207Pb) showed clearly that the source of Pb in the contaminated soil was mainly from anthropogenic sources.Therefore, from the Pb concentration and isotopic composition acquired, the Pb contamination was mainly sourced from anthropogenic activities from the study area. These sources mainly include scrap metal recycling industry, vehicle emission and domestic and industrial waste. So, more effective remediation strategies need to be developed to reduce the contamination

Yield response and economic implications of soybean (Glycine max (L.). Merrill) – upland-lowland rice sequential cropping in the rainforest/savanna transitory ecosystem

A sequential cropping system of soybean-lowland (NERICA L-42)-upland (NERICA 2) rice was established at Abeokuta and Ibadan (Nigeria) to evaluate the performance of the cropping system. Field trials were in split-split plot arrangement fitted into randomised complete block design and replicated three times. The first sequence had in the main plot tillage [minimum (MT) and conventional (CT)]. Soybean varieties TGx 1448-2E (V1) and TGx 1740-2F (V2) in sub-plot and spacing in sub-sub plot were 60 cm × 5 cm (R1), 60 cm × 10 (R2) and 60 cm × 15 cm (R3). Individual rice plots were established by dry dibble (DD) seeding and transplanting and sub-sub plot spacing were 15 cm × 15 cm (S1), 20 cm × 20 and 25 cm (S2) × 25 cm (S3). The sequence soybean (V1 CT R3); lowland and upland rice (S3 CT DD) was the most economically efficient (N 1,754 ha-1 day-1) in Abeokuta, while soybean (V1 MT R1) and lowland and upland rice (S1 DD MT) was the most economically efficient (N 1,858 ha-1 day-1) in Ibadan.</p