Research Article: Evaluation of soybean [Glycine max (L.) Merr.] genotypes for yield, water use efficiency, and root traits

Date Published: February 22, 2019

Publisher: Public Library of Science

Author(s): Harrison Gregory Fried, Sruthi Narayanan, Benjamin Fallen, Ricardo Aroca.

http://doi.org/10.1371/journal.pone.0212700

Abstract

Drought stress has been identified as the major environmental factor limiting soybean [Glycine max (L.) Merr.] yield worldwide. Current breeding efforts in soybean largely focus on identifying genotypes with high seed yield and drought tolerance. Water use efficiency (WUE) that results in greater yield per unit rainfall is an important parameter in determining crop yields in many production systems, and is often related with crop drought tolerance. Even though roots are major plant organs that perceive and respond to drought stress, their utility in improving soybean yield and WUE under different environmental and management conditions are largely unclear. The objectives of this research was to evaluate soybean cultivars and breeding and germplasm lines for yield, WUE, root penetrability of hardpan, and root morphology. Field experiments were conducted at two locations in South Carolina (southeastern United States) during the 2017 cropping season to test the genotypes for yield and root morphology under irrigated and non-irrigated conditions. Two independent controlled-environmental experiments were conducted to test the genotypes for WUE and root penetrability of synthetic hardpans. The slow wilting lines NTCPR94-5157 and N09-13890 had equal or greater yield than the checks- cultivar NC-Raleigh and the elite South Carolina breeding line SC07-1518RR, under irrigated and non-irrigated conditions. The high yielding genotypes NTCPR94-5157, N09-13890, and SC07-1518RR exhibited root parsimony (reduced root development). This supported the recent hypothesis in literature that root parsimony would have adaptational advantage to improve yield under high input field conditions. The high yielding genotypes NTCPR94-5157, N09-13890, NC-Raleigh, and SC07-1518RR and a cultivar Boggs (intermediate in yield) possessed high WUE and had increased root penetrability of hardpans. These genotypes offer useful genetic materials for soybean breeding programs for improving yield, drought tolerance, and/or hardpan penetrability.

Partial Text

Soybean [Glycine max (L.) Merr.] is the most widely grown legume in the world and the fourth most important crop after wheat (Triticum aestivum L.), maize (Zea mays L.), and rice (Oryza sativa L.) in terms of area harvested and production [1]. It is the most important oil seed in the world with a contribution of > 60% to the total oil seed production and > 70% to the total protein meal consumption [2]. Currently, three countries—United States, Brazil, and Argentina- account for > 80% of the global soybean production [2]. Sustainability of soybean production in all soybean producing regions worldwide is threatened by climate change and associated environmental stresses [3, 4]. Drought stress has been identified as the major environmental factor limiting soybean yield in the United States and other regions of the world [4, 5, 6, 7, 8, 9, 10, 11].

Current breeding strategies for soybean largely emphasize on drought tolerance as well as high seed yield. Since root morphological and anatomical traits are closely associated with whole-plant water acquisition, relevance and usefulness of these root traits in soybean breeding are gaining more importance in light of climate change and associated drought stress. However, high-throughput field-based root phenotyping techniques that allow simultaneous measurements of yield, WUE, and root traits are currently unavailable for field crops such as soybean [16, 58]. Therefore, this research that evaluated soybean cultivars and breeding and germplasm lines for yield, WUE, and root morphology provide valuable information to soybean breeding programs for yield improvement and drought tolerance.

The present study supports the recent hypothesis in literature that root parsimony (reduced root development) would have adaptational advantage to improve crop yield under high input field conditions. We found that the slow wilting lines NTCPR94-5157 and N09-13890 had equal or greater yield than the checks- cultivar NC-Raleigh and the elite South Carolina breeding line SC07-1518RR, under irrigated and non-irrigated conditions. Interestingly, the high yielding genotypes NTCPR94-5157, N09-13890, and SC07-1518RR exhibited root parsimony (reduced root surface area and volume). In addition, the above four high yielding genotypes and a cultivar Boggs (intermediate in yield) also possessed high WUE and had increased ability to penetrate hardpans. These five genotypes offer useful genetic materials for soybean breeding programs for improving yield, drought tolerance, and/or hardpan penetrability.

 

Source:

http://doi.org/10.1371/journal.pone.0212700

 

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