Omololu J. Idowu

Genetic variation and comparative analysis of thrips resistance in glandless and glanded cotton under field conditions

AbstractGlandless cotton can be grown for cottonseed free of toxic gossypol to be used as food and feed for non-ruminant animals. However, one of the most important limiting factors preventing its commercial production is its higher insect damage than conventional glanded cotton. Thrips is the one of the most important insect pests in the early growing season that may cause yield losses. In this study, 28, 29, 26, and 2 glandless cotton lines were compared with glanded control Acala 1517-08 and other glanded lines for resistance to the Western flower thrips, Frankliniella occidentalis (Pergande) in four replicated field tests each containing 32 genotypes. In the same field, 28 glanded commercial cultivars and 78 glanded breeding lines were compared with Acala 1517-08 and Acala 1517-99 in three other tests with 32 genotypes each. The experimental layouts allowed a comprehensive comparative analysis of thrips resistance within and between glandless and glanded cotton. Overall, glandless cotton had similar or lower thrips damages than glanded cotton, indicating that the glandless trait may serve as a genetic factor for suppressing thrips damage. As compared with Acala 1517-08 which represented one of the most thrips resistant genotypes among glanded cotton tested, glandless Acala GLS and many selections from glandless germplasm were more resistant, while some were similar to Acala 1517-08, indicating that genetic factors other than the glandless trait also affect thrips resistance in cotton. The estimates for broad-sense heritability for thrips resistance were moderate, indicating that thrips resistance is selectable. This is corroborated by the identification of many thrips resistant lines from a cross between Acala 1517-08 and Acala GLS. This study has laid a foundation for a more detailed study using most resistant lines with desirable agronomic traits in multiple environments.

Soil quality of semi-arid conservation reserve program lands in Eastern New Mexico

ABSTRACT A study was conducted to evaluate selected soil quality indicators in lands that have been in Conservation Reserve Program (CRP), which is a federal program in the United States offering annual rental payments and cost-share assistance to farmers who establish long-term vegetation covers on their erosion prone lands. The study site has semi-arid climate, and soils with grass vegetation covers for 15 years were compared with adjacent cultivated croplands that have never been in the CRP. Field measurements were performed and surface soil samples (0–0.15 m) were collected from multiple sites having either coarse textured or fine textured soils. Soil measurements assessed included bulk density (BD), penetration resistance (PR), wet aggregate stability (WAS), dry aggregate size distribution (DASD), soil organic matter (SOM), permanganate oxidizable carbon, nitrate nitrogen, extractable potassium and phosphorus, electrical conductivity, pH, sodium adsorption ratio, and soil micronutrients (copper, iron, manganese, and zinc). Results showed a significant effect of CRP management compared to the cropped fields for BD, WAS, and PR only, with the CRP fields being less compacted and having higher WAS than the cropped lands. CRP land did not significantly differ from cropped lands in SOM and for many other measurements. The effect of soil texture was significant for DASD, SOM, copper, and manganese, with the fine textured soils having more favorable measurements than the coarse textured soils. CRP management did not produce significant increase in topsoil SOM compared to cropped lands of the study area.

Current status, opportunities, and challenges of cover cropping for sustainable dryland farming in the Southern Great Plains

ABSTRACT Cropping systems that integrate cover crops into crop rotations, reduce tillage intensity and frequency, and maintain residue cover have the potential to improve agricultural sustainability in drylands. However, there is much yet to learn about the benefits of cover crops in sustainable dryland farming in the southern Great Plains (SGP). We reviewed the literature on the effects of cover crops on soil organic carbon (SOC), nitrogen, soil water conservation, and crop yields in dryland cropping systems of the US Great Plains (GP), and analyzed the opportunities and challenges for integrating cover crops into dryland crop-fallow systems of the SGP. Majority of the studies in the central Great Plains (CGP) and the northern Great Plains (NGP) of the United States suggest that cover cropping improves sustainability of cropping systems through their positive effects on SOC accumulation, nutrient cycling, soil erosion control, weed suppression, and soil health improvement. However, integrating cover crops into dryland cropping systems of the SGP faces challenges because of low quantity of soil-water availability. More research on the tradeoff between water use and other agroecosystem benefits of cover cropping is required to successfully integrate cover crops into dryland cropping systems in the SGP.

Short-Term Impacts of Pecan Waste By-Products on Soil Quality in Texturally Different Arid Soils

ABSTRACT Three arid soils (clay loam (CL), sandy clay (SC), and sandy loam (SL)) were amended with pecan waste products (ground pecan shells (PSHs), ground pecan husks (PHUs), and ground pecan shell biochar (PSB)), at a rate of 45 Mg/ha, packed inside cylindrical rings and kept in a humid chamber for 4 weeks. Measurements taken included volumetric moisture content as the soil dried out for 7 days, wet aggregate stability (WAS), permanganate oxidizable carbon (POXC), nitrate-nitrogen, extractable phosphorus (Olsen-P), and water-extractable potassium (K). Significant effects of soil texture, soil amendment, and their interaction were observed for all measurements. Generally, the amendments led to significant improvement in Olsen-P, K, POXC, and WAS, while amendments’ impacts on soils of different textures varied. Short-term moisture retention was dependent on soil texture, with PHU and PSB treatments having higher soil moisture retention in SL and CL soils but not in SC soil.