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F H Andrade - One of the best experts on this subject based on the ideXlab platform.
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maize grain yield components and Source Sink Relationship as affected by the delay in sowing date
Field Crops Research, 2016Co-Authors: Lucas E Bonelli, J P Monzon, Anibal Cerrudo, Roberto H Rizzalli, F H AndradeAbstract:Abstract Delaying maize ( Zea mays L.) sowing date can diminish grain yields through reductions in the number, size and activity of growing grains (Sink strength) and/or reductions in the assimilate supply (Source capacity) to grains during the grain filling period. Whether the Source capacity or the Sink strength is the limiting factor for grain yield in late sown maize still remains unclear. Understanding Source-Sink Relationships is relevant to optimize crop management practices, to identify critical processes for crop modelling and to develop breeding strategies. The objective of this work was to assess the effect of delays in maize sowing date on grain yield components and on the Source-Sink Relationship during the grain filling period. Three well irrigated and fertilized maize field experiments were conducted at Balcarce, Argentina (37° 45′ S, 58° 18′ W; 130 m a.s.l.) during 2009–10; 2010–11 and 2011–12 cropping seasons. Sowing dates ranged from October to January covering a broad range of the seasonal photo-thermal variation. Grain yield was affected by sowing date and varied from 1680 g m −2 (early sowings) to 203 g m −2 (late sowings). Grain number per unit area was reduced proportionally less than weight per grain as sowing date was delayed. Variations in grain yield were related to the harvest index, and were closely associated with dry matter accumulation during the post-silking period. The variation of Source capacity was higher than that of Sink strength during the grain filling period and the Source/Sink ratio decreased from early to late sowing dates. Results indicate that crop growth during the grain filling period was limited by the Sink strength in early sowing dates and by the photosynthetic Source capacity in the late ones.
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maize kernel moisture at physiological maturity as affected by the Source Sink Relationship during grain filling
Crop Science, 2007Co-Authors: Rodrigo G Sala, F H Andrade, Mark E WestgateAbstract:A wide range of values reported in the literature has precluded the use of grain moisture (GM) as an estimate of physiological maturity (PM) in maize (Zea mays L.). The reason for this variability in GM values remains unclear. Previous evidence suggests that the Source-Sink ratio could affect the dynamics of kernel water relations during grain filling and thus, GM at PM. To test this possibility, treatments were applied to manipulate the reproductive Sink capacity or the assimilate availability during grain filling. Kernel dry weight, water content, and the dry weight to water content (D-W) ratio, were monitored throughout grain filling. A bilinear model relating dry weight and GM was used to estimate GM at PM for each treatment. Severely restricting Source capacity during grain filling increased GM at PM. When the Source capacity per kernel during grain filling was increased, however, GM at PM was not affected. A single model (r 2 = 0.99, p < 0.001) described the Relationship between relative dry weight and GM for all hybrids and treatments without Source reduction during grain filling. The estimated value of GM at PM for this model was 34.9%. These results suggest that calculating GM late in grain filling can provide a reliable estimate of PM when the Source capacity has not been severely restricted. A value of 35% moisture would be adequate in these situations. The D-W ratio of developing kernels was similar across all Source-Sink treatments until PM. Premature cessation of grain filling caused by defoliation increased the D-W ratio as the kernels continued to desiccate.
Guanfu Fu - One of the best experts on this subject based on the ideXlab platform.
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abscisic acid synergizes with sucrose to enhance grain yield and quality of rice by improving the Source Sink Relationship
BMC Plant Biology, 2019Co-Authors: Tingting Chen, Guangyan Li, Mohammad Rezaul Islam, Weimeng Fu, Baohua Feng, Guanfu FuAbstract:BACKGROUND: Abscisic acid (ABA) and sucrose act as molecular signals in response to abiotic stress. However, how their synergy regulates the Source-Sink Relationship has rarely been studied. This study aimed to reveal the mechanism underlying the synergy between ABA and sucrose on assimilates allocation to improve grain yield and quality of rice. The early indica rice cultivar Zhefu802 was selected and planted in an artificial climate chamber at 32/24 °C (day/night) under natural sunlight conditions. Sucrose and ABA were exogenously sprayed (either alone or in combination) onto rice plants at flowering and 10 days after flowering. RESULTS: ABA plus sucrose significantly improved both the grain yield and quality of rice, which was mainly a result of the higher proportion of dry matter accumulation and non-structural carbohydrates in panicles. These results were mainly ascribed to the large improvement in sucrose transport in the sheath-stems in response to the ABA plus sucrose treatment. In this process, ABA plus sucrose significantly enhanced the contents of starch, gibberellic acids, and zeatin ribosides as well as the activities and gene expression of enzymes involved in starch synthesis in grains. Additionally, remarkable increases in trehalose content and expression levels of trehalose-6-phosphate synthase1, trehalose-6-phosphate phosphatase7, and sucrose non-fermenting related protein kinase 1A were also found in grains treated with ABA plus sucrose. CONCLUSION: The synergy between ABA and sucrose increased grain yield and quality by improving the Source-Sink Relationship through sucrose and trehalose metabolism in grains.
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heat stress reduced kernel weight in rice at anthesis is associated with impaired Source Sink Relationship and sugars allocation
Environmental and Experimental Botany, 2018Co-Authors: Caixia Zhang, Tingting Chen, Guangyan Li, Weimeng Fu, Baohua Feng, Hubo Li, Guanfu FuAbstract:Abstract Heat stress is one of the most limiting factors in rice plant growth and development. However, the impairment in the whole-plant carbohydrate partitioning at anthesis caused by heat stress is seldom documented. Two rice genotypes with different heat tolerance, namely Nipponbare (NIPP) and its high-temperature susceptible (HTS) mutant were subjected to heat stress of 40 °C for 12 d at anthesis. Heat stress significantly decreased the spikelet fertility and kernel weight, and a larger decline was found in HTS than in NIPP plants compared with their respective controls. However, there was no significant difference in photosynthesis in flag leaf and starch branching enzyme activity in grain between the control and heat-stress groups. Thus, heat stress-induced decline in kernel weight was most likely due to the inhibition of the assimilate distribution rather than the limitation of the Source and Sink. This assumption was confirmed by the distribution of dry mater weight, nonstructural carbohydrates (NSC) and starch in grain, leaf and sheath-stem observed under heat stress. Indeed, the sucrose transporter (SUT) genes, sucrose synthase (SUS) genes and phytohormones in grain and the callose deposition in plasmodesmata of leaf and sheath were involved in the process. However, the patterns of change in phytohormones in leaf and sheath-stem were different from those of carbohydrates, but exogenous sucrose alleviated the heat-stress effect on the spikelet fertility, kernel weight, dry matter weight accumulation and allocation. Thus, sugars rather than phytohormones might act as a signal molecule to mediate the Source-Sink Relationship in rice under heat stress.
Francisco Sotocarreno - One of the best experts on this subject based on the ideXlab platform.
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infuencia de tres fechas de siembra sobre el crecimiento y la relacion fuente demanda del cultivo del maiz zea mays l influence of three sowing dates on growth and Source Sink Relationship of maize zea mays l sowing
2012Co-Authors: Naivy Hernandezcordova, Francisco SotocarrenoAbstract:Con el objetivo de evaluar la influencia de tres fechas de siembra sobre el crecimiento y la relacion fuente demanda en el cultivo del maiz (Zea mays), se desarrollo el presente trabajo en el Instituto Nacional de Ciencias Agricolas; se estudiaron tres fechas de siembra: noviembre de 2008, junio de 2009 y julio de 2009, utilizandose una densidad de 50000 plantas.ha-1. Se realizaron muestreos destructivos cada 15 dias de emergidas las plantas hasta la cosecha, determinandoseles la masa seca total de la parte aerea y el Indice de Area Foliar (IAF), ajustandose los datos a una funcion exponencial polinomica de segundo grado, «x» fue los dias despues de la emergencia y «y» la variable en cuestion, a partir de las ecuaciones de regresion se calcularon la tasa de asimilacion neta (TAN) y la relacion de area foliar (RAF), tambien se calculo la relacion entre la potencia de la fuente y la potencia de la demanda, encontrandose que una mayor eficiencia en el uso de la radiacion conlleva a valores maximos mas elevados en la tasa de asimilacion neta (TAN) y en los potenciales entre los organos fuente y demanda y por tanto a una mayor acumulacion de biomasa en momentos proximos a la madurez fisiologica, destacandose en este caso en estudio la fecha de junio de 2009 la cual mostro una mayor eficiencia respecto a los indices evaluados alcanzandose en esta los mayores rendimientos Abstracts: The present work was performed at the National Institute of Agricultural Sciences in order to evaluate the influence of three sowing dates on maize growth and Source-Sink Relationship. Three sowing dates were studied: November 2008, June 2009 and July 2009 and a density of 5 000 plants.ha-1 was used. Plant samplings were made every 15 days, from 15 days after plant emergence until harvest; total shoot dry mass and foliar area index were determined. Data were adjusted to a second degree polynomial exponential function where «x» means days after emergence and «y» the variable in question. From the regression equations, the net assimilation rate (NAR) and leaf area ratio (LAR) were calculated. Source and Sink powers were also calculated. Results showed that a greater efficiency in the radiation use leads to higher peaks of net assimilation rate (NAR) and of the Source and Sink powers; therefore a greater biomass accumulation at the time closed to the physiological maturity of plants. In this case, June 2009 was the best sowing date because a highest efficiency of evaluated indexes and yields were obtained.
Francisco Soto Carreno - One of the best experts on this subject based on the ideXlab platform.
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influencia de tres fechas de siembra sobre el crecimiento y la relacion fuente demanda del cultivo del maiz zea mays l influence of three sowing dates on growth and Source Sink Relationship of maize zea mays l sowing
2012Co-Authors: Naivy Hernandez Cordova, Francisco Soto CarrenoAbstract:The present work was performed at the National Institute of Agricultural Sciences in order to evaluate the influence of three sowing dates on maize growth and Source-Sink Relationship. Three sowing dates were studied: November 2008, June 2009 and July 2009 and a density of 5 000 plants.ha -1 was used. Plant samplings were made every 15 days, from 15 days after plant emergence until harvest; total shoot dry mass and foliar area index were determined. Data were adjusted to a second degree polynomial exponential function where «x» means days after emergence and «y» the variable in question. From the regression equations, the net assimilation rate (NAR) and leaf area ratio (LAR) were calculated. Source and Sink powers were also calculated. Results showed that a greater efficiency in the radiation use leads to higher peaks of net assimilation rate (NAR) and of the Source and Sink powers; therefore a greater biomass accumulation at the time closed to the physiological maturity of plants. In this case, June 2009 was the best sowing date because a highest efficiency of evaluated indexes and yields were obtained. RESUMEN. Con el objetivo de evaluar la influencia de tres fechas de siembra sobre el crecimiento y la relacion fuente demanda en el cultivo del maiz (Zea mays), se desarrollo el presente trabajo en el Instituto Nacional de Ciencias Agricolas; se estudiaron tres fechas de siembra: noviembre de 2008, junio de 2009 y julio de 2009, utilizandose una densidad de 50000 plantas.ha -1 . Se realizaron muestreos destructivos cada 15 dias de emergidas las plantas hasta la cosecha, determinandoseles la masa seca total de la parte aerea y el Indice de Area Foliar (IAF), ajustandose los datos a una funcion exponencial polinomica de segundo grado, «x» fue los dias despues de la emergencia y «y» la variable en cuestion, a partir de las ecuaciones de regresion se calcularon la tasa de asimilacion neta (TAN) y la relacion de area foliar (RAF), tambien se calculo la relacion entre la potencia de la fuente y la potencia de la demanda, encontrandose que una mayor eficiencia en el uso de la radiacion conlleva a valores maximos mas elevados en la tasa de asimilacion neta (TAN) y en los potenciales entre los organos fuente y demanda y por tanto a una mayor acumulacion de biomasa en momentos proximos a la madurez fisiologica, destacandose en este caso en estudio la fecha de junio de 2009 la cual mostro una mayor eficiencia respecto a los indices evaluados alcanzandose en esta los mayores rendimientos.
J M Ferrero - One of the best experts on this subject based on the ideXlab platform.
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non uniform dispersion of the Source Sink Relationship alters wavefront curvature
PLOS ONE, 2013Co-Authors: Lucia Romero, Beatriz Trenor, J M Ferrero, Frank C StarmerAbstract:The distribution of cellular Source-Sink Relationships plays an important role in cardiac propagation. It can lead to conduction slowing and block as well as wave fractionation. It is of great interest to unravel the mechanisms underlying evolution in wavefront geometry. Our goal is to investigate the role of the Source-Sink Relationship on wavefront geometry using computer simulations. We analyzed the role of variability in the microscopic Source-Sink Relationship in driving changes in wavefront geometry. The electrophysiological activity of a homogeneous isotropic tissue was simulated using the ten Tusscher and Panfilov 2006 action potential model and the Source-Sink Relationship was characterized using an improved version of the Romero et al. safety factor formulation (SFm2). Our simulations reveal that non-uniform dispersion of the cellular Source-Sink Relationship (dispersion along the wavefront) leads to alterations in curvature. To better understand the role of the Source-Sink Relationship in the process of wave formation, the electrophysiological activity at the initiation of excitation waves in a 1D strand was examined and the Source-Sink Relationship was characterized using the two recently updated safety factor formulations: the SFm2 and the Boyle-Vigmond (SFVB) definitions. The electrophysiological activity at the initiation of excitation waves was intimately related to the SFm2 profiles, while the SFVB led to several counterintuitive observations. Importantly, with the SFm2 characterization, a critical Source-Sink Relationship for initiation of excitation waves was identified, which was independent of the size of the electrode of excitation, membrane excitability, or tissue conductivity. In conclusion, our work suggests that non-uniform dispersion of the Source-Sink Relationship alters wavefront curvature and a critical Source-Sink Relationship profile separates wave expansion from collapse. Our study reinforces the idea that the safety factor represents a powerful tool to study the mechanisms of cardiac propagation in silico, providing a better understanding of cardiac arrhythmias and their therapy.
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the relative role of refractoriness and Source Sink Relationship in reentry generation during simulated acute ischemia
Annals of Biomedical Engineering, 2009Co-Authors: Lucia Romero, Beatriz Trenor, Jose M Alonso, Catalina Tobon, Javier Saiz, J M FerreroAbstract:During acute myocardial ischemia, reentrant episodes may lead to ventricular fibrillation (VF), giving rise to potentially mortal arrhythmias. VF has been traditionally related to dispersion of refractoriness and more recently to the Source–Sink Relationship. Our goal is to theoretically investigate the relative role of dispersion of refractoriness and Source–Sink mismatch in vulnerability to reentry in the specific situation of regional myocardial acute ischemia. The electrical activity of a regionally ischemic tissue was simulated using a modified version of the Luo-Rudy dynamic model. Ischemic conditions were varied to simulate the time-course of acute ischemia. Our results showed that dispersion of refractoriness increased with the severity of ischemia. However, no correlation between dispersion of refractoriness and the width of the vulnerable window was found. Additionally, in approximately 50% of the reentries, unidirectional block (UDB) took place in cells completely recovered from refractoriness. We examined patterns of activation after premature stimulation and they were intimately related to the Source–Sink Relationship, quantified by the safety factor (SF). Moreover, the isoline where the SF dropped below unity matched the area where propagation failed. It was concluded that the mismatch of the Source–Sink Relationship, rather than solely refractoriness, was the ultimate cause of the UDB leading to reentry. The SF represents a very powerful tool to study the mechanisms responsible for reentry.
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The safety factor approach in the analysis of reentrant patterns of activation in the ischemic virtual heart
2007 Computers in Cardiology, 2007Co-Authors: L. Romero, J M Ferrero, B. Trenor, J. Saiz, G. Molto, J.m. AlonsoAbstract:Traditionally, VF has been directly related to dispersion of refractoriness. However, further theoretical studies relating refractoriness and reentry generation would be helpful to understand their implication. Recently, the safety factor for conduction (SF) has been proposed as a useful parameter to analyze propagation of action potential (AP) and conduction block. In this work, the relative role of refractoriness and the Source-Sink Relationship in conduction block leading to reentry during regional ischemia has been analyzed. Our results show that a) premature stimuli applied at CIs comprised between 170 ms and 204 ms lead to reentry, b) the distribution of SF during reentry is very similar for all the conducted simulations and c) in one third of the re-entries the premature stimulus was blocked at sites where the excitability of the cells was completely recovered.