Variation in shoot architecture traits and their relationship to canopy coverage and light interception in soybean (Glycine max).

BACKGROUND: In soybeans, faster canopy coverage (CC) is a highly desirable trait but a fully covered canopy is unfavorable to light interception at lower levels in the canopy with most of the incident radiation intercepted at the top of the canopy. Shoot architecture that influences CC is well studied in crops such as maize and wheat, and altering architectural traits has resulted in enhanced yield. However, in soybeans the study of shoot architecture has not been as extensive. RESULTS: This study revealed significant differences in CC among the selected soybean accessions. The rate of CC was found to decrease at the beginning of the reproductive stage (R1) followed by an increase during the R2-R3 stages. Most of the accessions in the study achieved maximum rate of CC between R2-R3 stages. We measured Light interception (LI), defined here as the ratio of Photosynthetically Active Radiation (PAR) transmitted through the canopy to the incoming PAR or the radiation above the canopy. LI was found to be significantly correlated with CC parameters, highlighting the relationship between canopy structure and light interception. The study also explored the impact of plant shape on LI and CO2 assimilation. Plant shape was characterized into distinct quantifiable parameters and by modeling the impact of plant shape on LI and CO2 assimilation, we found that plants with broad and flat shapes at the top maybe more photosynthetically efficient at low light levels, while conical shapes were likely more advantageous when light was abundant. Shoot architecture of plants in this study was described in terms of whole plant, branching and leaf-related traits. There was significant variation for the shoot architecture traits between different accessions, displaying high reliability. We found that that several shoot architecture traits such as plant height, and leaf and internode-related traits strongly influenced CC and LI. CONCLUSION: In conclusion, this study provides insight into the relationship between soybean shoot architecture, canopy coverage, and light interception. It demonstrates that novel shoot architecture traits we have defined here are genetically variable, impact CC and LI and contribute to our understanding of soybean morphology. Correlations between different architecture traits, CC and LI suggest that it is possible to optimize soybean growth without compromising on light transmission within the soybean canopy. In addition, the study underscores the utility of integrating low-cost 2D phenotyping as a practical and cost-effective alternative to more time-intensive 3D or high-tech low-throughput methods. This approach offers a feasible means of studying basic shoot architecture traits at the field level, facilitating a broader and efficient assessment of plant morphology.

Examining Between-Group Differences in Social Network Density and High-Sensitivity C-Reactive Protein in Older Adults: Implications for the Hispanic Mortality Paradox.

OBJECTIVE: Hispanic/Latino(x) and African American/Black older adults experience disproportionate cardiometabolic disease burdens when compared with their non-Hispanic White counterparts. Sources of resilience such as social networks have been found to mitigate the risk of this disease and its end points like high-sensitivity C-reactive protein (hs-CRP). However, little is known about the social network infrastructure among these groups. Moreover, existing work has largely ignored the degree to which members of one's network are connected to one another (network density), which may be important for navigating structural barriers within interdependent groups. The objective of this study was to understand the association between network density and 5-year hs-CRP (blood spot) and whether this association was moderated by race-ethnicity. METHODS: A subsample of Hispanic/Latino(x), African American/Black, and non-Hispanic White older adults ( N = 1431) from the National Social Life Health and Aging Project was used. Multivariable regression was used to estimate the association between network density and its interaction with race-ethnicity, with hs-CRP 5 years later. RESULTS: Although no main effect of network density on 5-year hs-CRP was found, results revealed a significant network density by race-ethnicity interaction (Wald χ2 (2, 1242) = 3.31, p = .037). Simple slopes analyses revealed that Hispanic/Latino(x) older adults with high network density had significantly lower hs-CRP levels when compared with their same-ethnic counterparts with low network density ( b = -0.73, standard error = 0.31, 95% confidence interval = -1.33 to -0.13, p = .018). CONCLUSIONS: Results demonstrate population-level differences in social network structure and differential associations of this infrastructure with health. Implications for the Hispanic Mortality Paradox are discussed.

An Examination of Sleep as a Mediator of the Relationship between Childhood Adversity and Depression in Hispanic and Non-Hispanic Young Adults.

The current study integrates previous research on adverse childhood experiences (ACEs) and long-term health outcomes to examine associations between ACEs, sleep duration, and depression in a diverse, mostly healthy, sample of young adults. We examine whether sleep duration mediates the association between ACEs and depression among young adults, and whether ethnicity may moderate observed relationships between ACEs, sleep duration and depression. Data were collected from 518 young adults (66.8% female, Mage=19.79 years, SDage=3.43 years) enrolled in undergraduate Psychology courses at a large Southwestern university. Participants primarily reported their racial/ethnic background as Non-Hispanic White (60.6%) and Hispanic/Latino (25.1%). Participants self-reported their ACEs exposure, sleep characteristics, and depressive symptoms. In addition to calculating overall exposure to ACEs, scores for the specific dimensions of adversity were also calculated (Abuse, Neglect, Exposure to Violence). Results supported a mediation model whereby higher reports of ACEs were associated with depressive symptoms both directly and through sleep duration. Results were not moderated by ethnicity. Findings provide support for sleep duration as one potential pathway through which ACEs may be associated with depressive symptoms in young adulthood, and suggest that this pathway is similar in Hispanic and non-Hispanic young adults.