Yields (seed number) increased over time with modern soybean genotypes. Seed protein concentration decreased over time. Nitrogen fertilization impacted yield via changes on the seed weight. Nitrogen limited yields for high‐yielding modern soybean genotypes. The United States (USA) and Argentina (ARG) account for over 50% of the global soybean [Glycine max (L.) Merr.] production. Soybean N demand is partially met (50–60%) by the biological nitrogen fixation (BNF) process; however, an unanswered scientific knowledge gap exists on the ability of the BNF process to fulfill soybean N demand at varying yield levels. The overall objective of this study is to explore the potential N limitation using different N strategies for historical and modern soybean genotypes. Four field experiments were conducted during 2016 and 2017 growing seasons in Kansas (USA) and Santa Fe (ARG). Twenty‐one historical and modern soybean genotypes released from the 1980s to 2010s were tested under three N treatments: (i) control, without N application (Zero‐N); (ii) 56 kg N ha−1 applied at R3‐R4 growth stages (Late‐N); and (iii) 670 kg ha−1 equally split at planting, R1, and R3–R4 growth stages (Full‐N). Historical soybean yield gains, from the 1980s to 2010s, were 29% in the USA and 21% in ARG. Following the yield trend, seed N content increased for modern genotypes in parallel to the reduction on seed protein concentration. Regarding N treatments, Full‐N produced 12% yield increase in the USA and 4% in ARG. Yield improvement was mainly related to increases in aboveground biomass, seed number (genotype effect), and to a lesser extent, to seed weight (N effect). This study suggests a potential N limitation for soybean, although there are still questions about the way in which N must be provided to the plant.
Soybean [Glycine max (L.) Merr.] seed N demand not met by biological N fixation is fulfilled by N remobilization from vegetative plant organs and N uptake from soil sources during the seed-filling period (SFP), herein termed N gain. The objectives of this study were to: (i) quantify the contribution of plant organs to N remobilization during the SFP, (ii) determine the association between N gain and N remobilization, and (iii) study the effect of seed yield in both N gain and N remobilization processes. Three field experiments were conducted in 2015 and 2016 in Kansas. Three soybean genotypes: (i) non-Roundup Ready (RR), released in 1997; (ii) RR-1, released in 2009; and (iii) RR-2, released in 2014 were tested under three N rates: (i) control without N application (zero-N); (ii) 56 kg N ha-1 applied at R3 stage (late N); and (iii) 670 kg N ha-1 (full N; three applications of 223 kg N ha-1) applied at planting, R1, and R3 stages. The late-N and full-N rates increased yields by 9% (256 kg ha-1) relative to the zero N. Neither genotypes nor N rates affected N gain nor N remobilization. Nitrogen remobilization accounted for 59% of seed N demand at maturity, mainly driven by biomass at R5.5, with the leaf organ as the main contributor (52%) of the total remobilized N. Nitrogen remobilization was negatively related to N gain, and increases in N gain were linked to increases in biomass and yield. core Ideas • Remobilization of N from vegetative organs fulfilled 59% of seed N, driven by plant biomass at R5.5. • There was a trade-off between N remobilization and N gain, connected to plant biomass and yield. • Greater yields relied on both N remobilization and N gain during seed filling.
Soybean [Glycine max (L.) Merr.] is the most important oilseed crop for animal industry due to its high protein concentration and high relative abundance of essential and non-essential amino acids (AAs). However, the selection for high-yielding genotypes has reduced seed protein concentration over time, and little is known about its impact on AAs. The aim of this research was to determine the genetic shifts of seed composition for 18 AAs in 13 soybean genotypes released between 1980 and 2014. Additionally, we tested the effect of nitrogen (N) fertilization on protein and AAs trends. Soybean genotypes were grown in field conditions during two seasons under a control (0 N) and a N-fertilized treatment receiving 670 kg N ha−1. Seed yield increased 50% and protein decreased 1.2% comparing the oldest and newest genotypes. The application of N fertilizer did not significantly affect protein and AAs concentrations. Leucine, proline, cysteine, and tryptophan concentrations were not influenced by genotype. The other AAs concentrations showed linear rates of decrease over time ranging from − 0.021 to − 0.001 g kg−1 year−1. The shifts of 11 AAs (some essentials such as lysine, tryptophan, and threonine) displayed a relative-to-protein increasing concentration. These results provide a quantitative assessment of the trade-off between yield improvement and seed AAs concentrations and will enable future genetic yield gain without overlooking seed nutritional value.
In July of 2016, abnormal ear development in corn (Zea mays L.) (barbell-ears, multiple ears per node herein termed as multi-ears, and short-husks) was reported in several cornfields that extended from the Texas Panhandle to eastern Colorado and East through Kansas, Nebraska, Iowa, and Illinois. Field surveys were conducted to study these ear abnormalities. Affected and unaffected plants were sampled from 15 farmer fields located in central and eastern Nebraska. Each plant was evaluated for ear type, ear placement, internode length, and grain yield. Along with plant evaluations, management practices and weather information were collected from the surveyed fields. Of the 15 surveyed fields, nine were grouped as affected (more than 10% abnormalities), and six were grouped as checks (<10% abnormalities). Affected fields averaged 26% of abnormalities, whereas check fields averaged only 4%. Ear abnormalities occurred on ears that seemed to be placed lower on plants relative to normal ears. Plants with abnormal ears had yield reductions between 35 and 91%, compared to plants with normal ears. Findings suggested that ear abnormalities may be a cumulative result from the classic genetic (hybrid-specific), environmental (stress factors), and management interactions. The study of underlying causes for abnormal ear development in corn is imperative for understanding the likelihood of future events occurring and providing critical information to potentially manage and mitigate these issues.
Intensive study for more than 100 yr has resulted in a good understanding of corn's (Zea mays L.) growth and development. However, abnormal development of ears in corn was reported in several U.S. states, including Texas, Colorado, Kansas, Nebraska, Iowa, and Illinois, during 2016, stretching our understanding. A comprehensive review of the literature was conducted to identify abnormal ears' symptoms, causes, and timing of development. This study aimed to (a) describe and summarize previously reported ear symptoms, (b) document recent widespread symptoms of major concern, and (c) describe our current understanding of the potential cause(s) and expected development timing for abnormal ears. In total, 10 previously reported symptoms of corn ears were found, including tassel, fasciated, arrested, pinched, blunt, silk-balled, incomplete kernel set, banana-shaped, zipper, and tipped-back. Three additional recent widespread symptoms of major concern associated with significant yield reduction across a wide area in 2016 were described: multi-ears, barbell-ears, and short-husk ears. The information available on several of the symptoms was limited, and the specific causes were unknown, highlighting the need for more research in this area. Despite this and based on existing knowledge, possible causal factors and postulated development timing (i.e., when the stress may have occurred) are presented for all symptoms. Abnormal ear development can be seen as the response to complex interactions among genetics, environment, and management practices. Ear abnormalities are detrimental to grain yield and quality, and their mitigation is imperative to efficient corn systems, crop resiliency, and sustainability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.