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Title:Agronomic management and biostimulants to increase corn and soybean productivity
Author(s):Ehnle, Keith Edward
Advisor(s):Below, Frederick E
Contributor(s):Brown, Howard; Lee, DoKyoung
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agronomic Management
Abstract:Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] have been in production in the Corn Belt together since the 1920s. Improved cultivars and crop management has allowed for ever-increasing corn and soybean grain yields. Management factors that have played a big role in the yield increases are nitrogen (N) fertility, plant population, foliar protection, hybrid/variety, and additional nutrient fertility. Recently another management factor, biostimulants, is being evaluated as an option to further increase grain yield. Biostimulant products vary in their function, but all interact with at least one other management factor. The dependence of a biostimulant product’s efficacy on these interactive effects can make it hard to predict the grain yield response of the crop. In an attempt to further understand the newest and fastest growing sector of the crop production agriculture industry, the objective of this research was to evaluate two different biostimulant products for their ability to increase growth and yield of soybean, and N use and productivity of corn. This research involved the following two studies. Exploring the Interaction of Agronomic Management and a Plant Growth Regulator to Increase Productivity of Soybean Biostimulants are becoming the newest products of interest in the agriculture industry, due to the wide array of influences on row crops and multiple modes of action. Consequently, there is a large array of products on the market with minimal government regulation because it is hard to discern how the biostimulant’s effect would change with different interactions in the environment and when combined with management factors that impact soybean productivity. Therefore, understanding the interaction of a wide range of plant populations with a foliar-applied auxin inhibiting plant growth regulator (AIPGR) applied with or without foliar protection would aid farmers in increasing soybean grain yield productivity. The objective of this research was to quantify differential growth and yield responses of soybean grown at varying plant populations to an AIPGR biostimulant applied during vegetative or reproductive growth as well as with and without foliar protection. Soybean was sown at three locations in Illinois (northern, central, and southern) to achieve low (80,000 plants acre-1), standard (140,000 plants acre-1), and high (200,000 plants acre-1) plant populations. In 2019, at each plant population, plants either received the AIPGR (GRAP GRAD; Agrocete, Cara-Cara, Paraná, BR) at the V5, R3, or V5 + R3 growth stage(s). Additionally, foliar protection (fungicide and insecticide) was applied to half of the plots that received the AIPGR at either the R3 growth stage or both V5 + R3 growth stages. The control plots at each plant population in 2019 included plants that received no foliar applications and plants that solely received foliar protection (fungicide and insecticide) application. In 2020, the same plant populations were used with foliar treatments implemented of an untreated control, AIPGR applications at the V5, R3, or V5 + R3 growth stage(s), with foliar protection on half of the AIPGR-treated plots. In both years, on average, the plant population producing the highest grain yield was 200,000 plants acre-1, while the highest grain-yielding treatment was AIPGR applied at V5 + R3 with a foliar protection application. Increases in grain yield were typically driven by greater seed weight, in response to either greater plant population and/or foliar applications. Additionally, increasing the plant population tended to decrease the number of branches per plant. Overall, the results showed that the greatest yield was generated by planting 200,000 plants acre-1, applying AIPGR at both the V5 + R3 growth stages, and applying foliar protection. Enhancing Nitrogen Uptake and Corn Productivity with Azospirillum brasilense Of the many new biostimulant products, nitrogen-fixing bacteria (NFB) are possibly the most popular, because of the interest in reducing the need for the most-abundantly applied nutrient to a corn crop, nitrogen (N). Many NFB exist, but few studies have examined their effect on growth, nutrient uptake, and yield of corn. The objective of this research was to investigate the effects of a NFB, Azospirillum brasilense, in combination with varying N supplies at multiple environments on growth, N accumulation, and yield of corn. In 2019 and 2020, corn was grown in a five-rate N titration of 0, 50, 100, 150, and 200 lbs N acre-1 both with and without A. brasilense (GRAP NODa; Agrocete). Nitrogen treatments were broadcast and incorporated preplant as urea with A. brasilense applied in-furrow at the time of planting. In both years, the studies were conducted at three sites including northern, central, and southern locations, which have varying weather and native soil properties. Despite the varying environments, there were similar responses between locations and years. At the northern location in 2020, central location in 2019, and southern location in 2019 A. brasilense application tended to increase grain yield from 2 to 12 bushel acre 1 at the low N rates (0 and 50 lbs N acre-1). However, there were also grain yield decreases in response to A. brasilense application, ranging from 3 to 22 bushel acre-1 in combination with the moderate N rates (100 and 150 lbs N acre-1). The grain yield increases due to the application of A. brasilense, tended to be a result of greater kernel number at the lower N rates. Increases in plant N uptake at V8 and R6 in response to A. brasilense tended to be associated with the incidences of grain yield increase. Overall, the response of corn to the in-furrow applications of A. brasilense was highly dependent on the environment, with more positive responses at the higher-yielding environments.
Issue Date:2021-04-29
Rights Information:Copyright 2021 Keith Ehnle
Date Available in IDEALS:2021-09-17
Date Deposited:2021-05

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