Impacto de la variabilidad genotípica y ambiental sobre los carbohidratos solubles en el grano de soja

Optimizar la fecha de siembra del cultivo resulta crítico para maximizar el rendimiento (Di Mauro et al., 2018). Sin embargo, sus efectos sobre la calidad de los granos, más allá de la concentración de proteína y aceite, han sido raramente descriptos (Bosaz et al., 2019).A los efectos prácticos, el grano de soja está compuesto por: proteína, aceite y residual. El residual contiene cenizas, carbohidratos solubles (azúcares y oligosacáridos) e insolubles (celulosa y hemicelulosa) y lignina. Estos últimos son los componentes mayoritarios de la fibra dietaria (Westgate, 1999). La proteína y el aceite son los componentes de mayor valor económico y nutricional, representando en conjunto el 60% del peso del grano expresado en base seca, las cenizas corresponden a un 5% aproximadamente, mientras que un 35% pertenece a carbohidratos. Estos últimos se encuentran principalmente en la cubierta, pero también se pueden encontrar en las células del parénquima del embrión. Una porción de carbohidratos y lignina se elimina con las cascarillas, pero la harina de soja puede todavía contener hasta un 40% de carbohidratos totales (Medic et al., 2014). El residual es la fracción menos estudiada del grano de soja por ser el componente de menor retribución monetaria y calidad nutricional (Middelbos y Fahey, 2008). Sin embargo, su concentración y composición puede afectar el rendimiento y calidad de los ingredientes proteicos derivados. El residual, contiene rafinosa y estaquiosa, dos galactooligosacáridos de tres y cuatro monómeros respectivamente, con efectos antinutricionales. Estos oligosacáridos producen una disminución en la absorción intestinal de nutrientes, flatulencias y diarrea en cerdos, perros y humanos (Kumar et al., 2010). Genotipos con baja concentración de estaquiosa y elevada concentración de sacarosa han sido desarrollados para evitar dichas características. Su utilización en la elaboración de ingredientes proteicos ha conducido a una disminución en la concentración de estaquiosa en los mismos, aumentando la eficiencia del proceso y generando propiedades funcionales únicas (Deak y Johnson, 2006).El objetivo de este estudio consistió en describir cómo los genotipos (G) y el ambiente (A) afectan a la proteína, el aceite y los carbohidratos solubles (estaquiosa, rafinosa, glucosa y fructosa) dentro de la fracción residual en el grano de soja.Fil: Lopez, E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Alvarez Prado, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Corteva Agriscience; Estados UnidosFil: Gerde, Jose Arnaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentin

Morpho-physiological traits associated with drought responses in soybean

Drought is currently a major constraint to soybean [Glycine max (L.) Merr.] production worldwide and is becoming more widespread due to increased aridity and warmer temperatures in the context of global climate change. In this context, breeding for soybean varieties more tolerant to drought stress is critical and requires efficient screening techniques. To find traits associated with drought tolerance at the vegetative stage that are still present at the reproductive stage, we evaluated morphological, physiological, and biochemical traits in two soybean genotypes contrasting in their response to drought stress. Under drought stress at the vegetative stage, the tolerant A 5009 RG genotype showed higher proline and chlorophyll contents, and early activation of the enzymatic antioxidant system compared with well-watered plants. On the other hand, the sensitive ADM 50048 genotype increased malondialdehyde (oxidative damage marker) and nonenzymatic antioxidant response under stress. Manipulative field assays under contrasting levels of water availability at the reproductive stage mimicked the biochemical patterns observed in the greenhouse tests for the sensitive and tolerant genotypes. A principal component analysis of parameters from vegetative and reproductive stages revealed proline and chlorophyll contents as drought tolerance traits in soybean. We found those traits useful to classify 14 genotypes from the Instituto Nacional de Tecnologia Agropecuaria (INTA) germplasm bank, identifying two new drought-tolerant genotypes (PI 548510 and PI 200492). We propose proline and chlorophylls as useful tools to classify soybean genotypes according to their drought responses in early developmental stages, potentially reducing breeding times.Fil: Guzzo, Maria Carla. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Estudios Agropecuarios; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Costamagna, Carla Antonella. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Estudios Agropecuarios; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Salloum, Maria Soraya. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Estudios Agropecuarios; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Monteoliva, Mariela Inés. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Estudios Agropecuarios; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina. Oklahoma University; Estados UnidosFil: Luna, Celina Mercedes. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Estudios Agropecuarios; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentin

Reduced soybean photosynthetic nitrogen use efficiency associated with evolutionary genetic bottlenecks

Soybean has a narrow genetic base thought to limit future yield genetic gains. However, there is no evidence whether this reduction in genetic diversity correlates with diversity loss for any yield trait. We tested how photosynthetic nitrogen use efficiency (leaf photosynthesis per unit nitrogen, NUEp) evolved from the wild relative Glycine soja Siebold & Zucc. to the current Glycine max (L.) Merr. Five populations resulting from different evolutionary bottlenecks were evaluated under field conditions. Populations were wild ancestors, domesticated Asian landraces, North American ancestors, and modern cultivars. Genotypic differences in photosynthesis and leaf nitrogen were evident, creating a significant 3-fold variation in phenotypic NUEp. There was a parallel reduction in molecular marker and phenotypic NUEp diversity after each evolutionary bottleneck. G. soja had three times more NUEp diversity and 25% more average NUEp compared with the elite modern cultivars. Two strategies for increasing NUEp were identified: (i) increases in light saturated photosynthesis (Pmax), and, alternatively, (ii) reductions in leaf nitrogen. A modelling approach showed that NUEp will increase yield only if based on increased Pmax. Our study quantified the genetic potential of exotic germplasm available for trait-directed breeding. Results antagonise the concept that elite germplasm is always superior for any relevant yield trait when compared with undomesticated germplasm.Fil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Borras, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin

Explorando manejos agronómicos en pisos y techos de producción de soja el Sur Santafesino

Importancia relativa del manejo agronómico en diferentes ambientes productivos, asociado a los techos y pisos de producción sojera.Fil: Di Mauro, Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentin

Biological limits on nitrogen use for plant photosynthesis: a quantitative revision comparing cultivated and wild species

- The relationship between leaf photosynthesis and nitrogen is a critical production function for ecosystem functioning. Cultivated species have been studied in terms of this relationship, focusing on improving nitrogen (N) use, while wild species have been studied to evaluate leaf evolutionary patterns. A comprehensive comparison of cultivated vs wild species for this relevant function is currently lacking. We hypothesize that cultivated species show increased carbon assimilation per unit leaf N area compared with wild species as associated with artificial selection for resource-acquisition traits. - We compiled published data on light-saturated photosynthesis (Amax) and leaf nitrogen (LNarea) for cultivated and wild species. The relationship between Amax and LNarea was evaluated using a frontier analysis (90th percentile) to benchmark the biological limit of nitrogen use for photosynthesis. - Carbon assimilation in relation to leaf N was not consistently higher in cultivated species; out of 14 cultivated species, only wheat, rice, maize and sorghum showed higher ability to use N for photosynthesis compared with wild species. - Results indicate that cultivated species have not surpassed the biological limit on nitrogen use observed for wild species. Future increases in photosynthesis based on natural variation need to be assisted by bioengineering of key enzymes to increase crop productivity.Fil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Cipriotti, Pablo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Nutritional and environmental effects on biological nitrogen fixation in soybean: a meta-analysis

Biological N2 fixation (BNF) and mineral soil absorption are complementary N sources for soybean growth. BNF is sensitive to nutrient and environmental conditions, though a comprehensive synthesis of the studies underlying these conclusions is currently lacking. Our objective was to conduct a meta-analysis of nutrient and environmental effects on BFN. Articles reporting manipulative treatments and BNF estimations were compiled, and data and metadata were extracted. N fertilization reduced BNF ∼70% relative to the unfertilized control in greenhouse experiments and ∼44% in field experiments. This effect was higher for vegetative than for reproductive stage applications. Fertilization with other nutrients stimulated BNF relative to the unfertilized treatments. Water stress reduced BNF 40% relative to the unstressed control. The negative impact of water stress was larger when stress was applied at vegetative (-70%) compared to reproductive (-30%) stages. Flooding reduced BNF by 40% relative to the non-flooded control with highest effect when applied during vegetative stage (-82%). Increased temperature reduced BNF nitrogenase activity. Carbon dioxide enrichment has a stimulatory effect on BNF. With the exception of N fertilization, soybean and Rhizobium fitness showed a high positive correlation across nutrients and environmental factors. This work summarizes for the first time the impact and relative response of BNF to different nutrient and environmental factors. Results showed an initial critical stage (i.e. vegetative stage) for BNF that is common to most environmental factors negatively affecting BNF. This suggests that common strategies might exist to increase BNF that are independent of the specific identity of the stressor. Also, the positive correlation between host and Rhizobium fitness suggest that strategies to increase BNF potential are the same that those required to increase crop performance. We observed publication bias for some variables, suggesting that effect sizes might be inflated compared to true effect sizes. The only way to solve this problem is to find venues for publication of no significant results when sound experimental approaches and reasonable statistical power can be proved.EEA OliverosFil: Santachiara, Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentina.Fil: Salvagiotti, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Oliveros; ArgentinaFil: Rotundo, José Luis. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentina

Physiological processes leading to similar yield in contrasting soybean maturity groups

Soybean [Glycine max (L.) Merr.] maturity groups (MGs) exhibit large variation in time to maturity, and are adapted to different latitudes. There is a range of MGs that have similar yield potential at most production regions, especially at temperate and tropical environments. We tested whether similar yields in contrasting MGs are achieved through different physiological processes. Our objectives were: (i) to characterize biomass accumulation, reproductive partitioning and seed set efficiency, and (ii) to analyze the role of N and radiation in biomass accumulation during the seed set period in contrasting MGs. Three MG III and V cultivars were tested in two growing environments. No significant yield or seed number differences were detected despite MG V had 20 d longer growth cycle. MG III had a longer seed set period (R1–R5), received more incident radiation during that period, and captured more N compared to the MG V. However, these cultivars had lower nitrogen use efficiency (NUE) (g biomass per g N uptake) and less radiation interception efficiency compared to MG V. These contrasting physiological processes determined similar biomass accumulation during R1 to R5. No differences between MGs were observed in biomass partitioning to reproductive structures and seed set efficiency during this period. Results showed contrasting MGs have different strategies for reaching similar yield, evidencing physiological processes that could be specifically tailored by breeders for either MG III (radiation interception efficiency, NUE) or MG V (duration of R1–R5 period, N uptake rate) cultivars for further yield increases.Fil: Santachiara, Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Borras, Lucas. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rotundo, José Luis. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Source of resistance aff ect soybean yield, yield components, and biomass accumulation in Heterodera glycines-infested fields

The soybean cyst nematode (Heterodera glycines Ichinohe) is the main yield limiting pathogen of soybean [Glycine max (L.) Merr.] in the USA. Resistant cultivars are the most efficient management tool today. Our research studied the physiological basis of yield differences between H. glycines-susceptible and H. glycines- resistant cultivars developed from the Hartwig, PI 88788, and Peking sources of resistance at two locations in Iowa during 2005 and 2006. Supplementing resistance with chemical control may improve soybean yield and/or nematode control, so nematicide application {aldicarb[2-methyl-2 (methylthio) propionaldehyde O-(methylcarbamoyl) oxime]} was included as an experimental factor. Aldicarb increased total plant biomass by 9% during R1-R5 soybean growth stages, but there was no increase in seed yield. Yields of the resistant cultivars were greater than those of the susceptible cultivars, except for the Peking source. Compared with the susceptible cultivars, cultivars with H. glycines resistance from PI 88788 had a 13% increase in yield associated with a 15% increase in growth during R1-R5. In cultivars with resistance from Hartwig, a 6% increase in yield was associated with a 4% increase in R1-R5 duration and increased seed-set efficiency. This work demonstrates that yield increases due to resistance to H. glycines can be attained by different physiological mechanisms associated with the different resistance sources and probably are controlled by different genes. This opens the possibility of pyramiding genes conferring resistance by different mechanisms. © Crop Science Society of America.Fil: Rotundo, José Luis. University of Iowa; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Tylka, G.L.. Syngenta Crop Protection; Estados UnidosFil: Pedersen, P.. University of Iowa; Estados Unido

Understanding erratic germination in perennial grasses using physiological models and field experimentation.

Year-to-year variability in field seedling emergence in arid rangelands poses questions about the viability of perennial grasses threatened by overgrazing. There are practical difficulties in estimating long-term seedling emergence for perennial species with erratic behavior (high temporal variability). We present a novel approach combining seed germination studies, modeling, and field experiments to estimate long-term germination probability using Poa ligularis as a perennial grass model. Additional objectives were to evaluate: (i) germination requirements of different P. ligularis populations, (ii) field emergence behavior at two extreme locations within the distributional range in the southern region, and (iii) the influence of microsite or local soil on field emergence. Germination parameters were obtained from 8 populations collected across a 12° latitude transect. Germination parameters were combined with a soil water model to estimate long-term germination (used as a proxy of field emergence) in the southernmost location. Germination requirements differed across populations and correlated with environmental conditions of collection sites, demonstrating ecological significance. Field experiments showed very low emergence. Simulations for the southern location indicated erratic emergence. Fifty percent of the years had nil simulated field emergence and the magnitude of the events, when occurred, was small. The magnitude of these events depended on the population, demonstrating an additional genetic constraint. Erratic field emergence arises from the mismatch between environmental conditions and germination requirements. Knowing favorable climatic conditions triggering seed germination (and thus emergence) events are key for opportunistic management of species with this erratic behavior.Fil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Aguiar, Martin Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Benech-arnold, Roberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Variation in seed protein concentration and seed size affects soybean crop growth and development

Developing high protein (HP) cultivars is often precluded by the inverse relationship between protein and yield. We hypothesized that attaining HP concentration based on contrasting seed size impacts crop growth and development differently. We screened 97 soybean genotypes and found lines with HP concentration (~450 g kg−1) associated with (i) increased protein content (mg seed−1) in large seed genotypes, and (ii) reduced oil and carbohydrate contents in small seed ones. Then, we evaluated different growth traits in a subset of three HP large and three HP small seed genotypes, as well as in three high-yielding genotypes with average seed size and protein concentration. High-yielding genotypes showed higher leaf area duration and harvest index when compared with HP genotypes, regardless of seed size. High protein large seed was associated with more assimilate availability per seed during seed filling, while HP small seed showed higher leaf area at the beginning of seed fill, more canopy biomass production, and very low levels of assimilate per seed. Results show that selecting for seed protein concentration can impact crop growth and development differently, depending on the strategy used for selection in terms of seed size. These findings, if utilized for parental selection, might contribute to eliminating negative correlations between seed protein and yield, since these strategies may be under different genetic control and/or determine different biophysical constraints.Fil: Poeta, Florencia Belen. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; ArgentinaFil: Borras, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; ArgentinaFil: Rotundo, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentin