SEASONAL VARIATIONS IN THE CHEMICAL COMPOSITION OF GRASSES HARVESTED FROM THE NATURAL PASTURE IN OGUN STATE SOUTH-WESTERN NIGERIA

The research was carried was carried out to evaluate the chemical composition of the dominant grasses harvested from the natural pasture in selected villages in Ogun State, South-western Nigeria at different seasons. The study was carried out using a 4 × 6 factorial arrangement comprising four seasons (early rain, late rain, early dry and late dry) at six locations (Afami, Atokun, Ibooro, Ileniku, Ipaaya, and Okerori). Results showed that the crude protein (CP) content significantly (p<0.05) varied from 5.56 % for Okerori to 7.34 % for Ibooro and the grasses harvested at Afami had the highest (72.75 %) neutral detergent fibre (NDF) values with the least (68.75 %) value recorded for Okerori, while the acid detergent fibre (ADF) values ranged from 41.00 % for Atokun to 48.25 % for Okerori. Also, CP value as affected by the season ranged from 4.23 % for late rainy to 9.44 % for the early rainy season and NDF values from 67.33% for late dry to 72.33 % for late rainy season while the early dry season had the highest value (48.00 %) for ADF with the least value (40.33 %) was recorded for the early rainy season. The phosphorus (P) value was highest at Ipaaya (2.99 g/kg) with the least value observed at Okerori (1.62 g/kg). The value for calcium ranged from 2.55 g/kg at Afami to 6.59 g/kg at Okerori. The P value of grasses as affected by seasons ranged from 1.46 g/kg for early dry to 2.66 g/kg for early rainy seasons.

Effects of mowing dominant grasses on root exudation and soil nitrogen cycling in a natural sod culture apple orchard

We evaluated the effects of mowing dominant grasses on root exudation and soil nitrogen (N) cycling by assessing metabolomics analysis of root exudates, microbial metabolism, the abundance of N-cycling-related prokaryotes, and different forms of N concentrations in soil. The treatments included Polygonum aviculare L. mowing (T1), Digitaria sanguinalis (L.) Scop. mowing (T2), and no mowing as the controls (CK1 and CK2). The results showed that compared with the no mowing control (CK1 and CK2), T1 and T2 root exudates contained 223 (178 up-regulated, 45 down-regulated) and 183 (40 up-regulated, 143 down-regulated) differential metabolites, respectively. The average well colour development (AWCD) could reflect the microbial metabolic activity. The AWCD values of T1 were increased while that of T2 decreased on the 2^nd day after mowing. The variation in root exudates was the main reason for the change in soil AWCD values and carbon utilisation of T1 and T2 on the 2^nd day after mowing. Mowing increased soil microbial biomass N content significantly in the T1 and T2 topsoil. The NO₃^–-N and NH₄⁺-N contents in the 0–10 cm soil increased on the 2^nd day after T1 mowing with an increase in the nitrogenase iron protein gene (nifH), glutamate dehydrogenase gene (gdh), ammonia monooxygenase gene (amoA) of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) abundance. However, NO₃^–-N content decreased on the 2^nd day after T2 mowing following a decrease in AOA-amoA and AOB-amoA gene abundance. The results of this study will facilitate the optimisation of sod culture orchard N management, reduction of N fertiliser input, and improvement of N utilisation efficiency.

Grazing exclosures reveal divergent patterns of change in bunchgrass grasslands of Western Canada

Thirty-six long-term (14–83 years) cattle grazing exclosures and adjacent grazed pastures spanning a climatic gradient from cooler–wetter to warmer–drier growing seasons in south-central British Columbia were compared for temporal vegetation change. Trajectories of temporal vegetation change from non-metric multidimensional scaling were mostly scattered for the grazed areas, but more directed toward the dominant grasses, primarily rough fescue (Festuca campestris) or Kentucky bluegrass (Poa pratensis), for the exclosures. Plant community differences, detected only after 10 years of grazing exclusion, were primarily due to structural shifts in overall species cover related to growth increases of the dominant grasses inside exclosures. Species richness remained unchanged between the first and last sampling dates in both grazed areas and exclosures, with both treatments showing moderate degrees (15%–30%) of turnover in species composition. Shannon diversity declined in both treatments as a result of the structural changes in species cover. The results highlight the value of repeated monitoring of long-term exclosures for assessment of grassland resiliency to grazing. Further studies of the interaction of grazing and climate are needed for a more complete understanding of the ongoing vegetation change.

Arbuscular Mycorrhizal and endophytic (DSE) association in the dominant grasses of Melghat forest (Phase -I), India

Investigations on arbuscular mycorrhizal Fungi (AMF) and dark septate endophytic (DSE) association in some of the dominant grasses from Melghat forest (phase I) of Satpura terrain India, was carried out to examine their existence and symbiotic relationships with the host plants. This forest area was not surveyed earlier by anybody to evaluate the AMF status diversity hence it was decided to survey the buffer and core area. Rhizosphere soil of each sampled grass was analyzed for the AM fungal structures in the roots to study percent root colonization by AMF and AMF spore density in rhizospheric soils of respective samples. The composite soil sample was prepared for each site and used for physicochemical analysis by standard methods. In the first phase of project, forty-eight dominant grass species from twenty-one different sites were collected along with roots and rhizospheric soil to find out AMF and DSE status of grasses. Both type of fungal associations was found in almost all the grass species collected during studies. All of them were found colonized by AMF hyphae along with moderate to poor development of mycorrhizal structures in roots. DSE colonization was also found in maximum forty-three grasses. Physico- chemical characterization of all the soil samples were performed to find out its correlation with AM percent colonization and spore count. Mean AMF percent colonization were in between 1.33 to 52.85 and DSE in with 0.00 to 18.97. Viable AM spore count were in between 0 to 98 per 100g of soil. Altogether four AMF genera with its thirty-nine-different species were isolated and identified. A data base of indigenous AM species richness for Melghat forest has been generated to plan and design the future management practices for grasses establishment and development especially in burnt and over grazed areas.