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Gustavo A. Slafer - One of the best experts on this subject based on the ideXlab platform.
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Floret development and spike fertility in wheat differences between cultivars of contrasting yield potential and their sensitivity to photoperiod and soil n
Field Crops Research, 2020Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Abstract In a previous paper (Field Crops Res. 203, 114–127), we showed that the difference in yield potential between a contemporary and a traditional cultivar was due to differences in fruiting efficiency, likely derived from differences in spike fertility (fertile Florets per spike) while having similar spike dry weights at anthesis. In this study, we determined the mechanistic bases of these genotypic differences in spike fertility analysing the initiation of all Floret primordia per spike (up to 8), the maximum number of Florets initiated per spikelet, and the associated Floret developmental rates and their fate to become fertile Florets under contrasting photoperiod (natural vs extended) and nitrogen availability (50 or 200 kg N ha−1) during the stem elongation phase. Under potential growing conditions (natural photoperiod, high nitrogen availability), the contemporary cultivar owed its higher spike fertility to the improved rate of Floret development, which mainly determined an improved level of Floret primordia survival to produce fertile Florets. The sensitivity of the Floret developmental patterns to faster development due to exposure to an extended photoperiod and, to a larger extent, a reduction in N availability was similar for both cultivars, providing a basis for the consistent differences in spike fertility across a range of environments. The response again determined a main effect through increasing Floret mortality reducing therefore the level of fertile Florets per spikelet in these conditions.
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earliness per se temperature interaction consequences on leaf spikelet and Floret development in wheat
Journal of Experimental Botany, 2020Co-Authors: Paula Prieto, Simon Griffiths, Helga Ochagavia, Gustavo A. SlaferAbstract:Wheat adaptation can be fine-tuned by earliness per se (Eps) genes. Although the effects of Eps genes are often assumed to act independently of the environment, previous studies have shown that they exhibit temperature sensitivity. The number of leaves and phyllochron are considered determinants of flowering time and the numerical components of yield include spikelets per spike and fertile Floret number within spikelets. We studied the dynamics of leaf, spikelet, and Floret development in near isogenic lines with either late or early alleles of Eps-D1 under seven temperature regimes. Leaf appearance dynamics were modulated by temperature, and Eps alleles had a greater effect on the period from flag leaf to heading than phyllochron. In addition, the effects of the Eps alleles on spikelets per spike were minor, and more related to spikelet plastochron than the duration of the early reproductive phase. However, fertile Floret number was affected by the interaction between Eps alleles and temperature. So, at 9 °C, Eps-early alleles had more fertile Florets than Eps-late alleles, at intermediate temperatures there was no significant difference, and at 18 °C (the highest temperature) the effect was reversed, with lines carrying the late allele producing more fertile Florets. These effects were mediated through changes in Floret survival; there were no clear effects on the maximum number of Floret primordia.
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physiological determinants of fertile Floret survival in wheat as affected by earliness per se genes under field conditions
European Journal of Agronomy, 2018Co-Authors: Paula Prieto, Simon Griffiths, Roxana Savin, Helga Ochagavia, Gustavo A. SlaferAbstract:Abstract Variations in wheat yield are largely explained by changes in grain number per m2 which is linked to the number of fertile Florets at anthesis. This, in turn is the outcome of developmental processes which control Floret initiation and mortality. Earliness ‘per se’ (Eps) genes are involved in fine-tuning time to anthesis in wheat (and other cereals) but their effect on development prior to anthesis is less well studied. We aimed to determine effects of Eps genes on spike fertility, quantifying aspects of Floret developmental which influence this trait. Field experiments were carried out to record Floret primordia generation/degeneration dynamics in near isogenic lines (NILs) with contrasting Eps alleles (late flowering vs early flowering alleles; Eps-late and Eps-early, respectively) derived from the Avalon x Cadenza (AxC) cross with the Eps gene on either chromosome 1D or 3 A and from the Spark x Rialto (SxR) cross with the Eps gene on chromosome 1D. Eps NILs varied in spike fertility: Eps-late alleles increased fertility. Although the effect was in general slight, the magnitude was affected by the particular alleles and the cross used to produce the NILs. Differences in the number of fertile Florets were explained by differences in the dynamics of Floret development. NILs with Eps-late alleles improved the development of a small number of labile Florets allowing them to complete their development to become fertile Florets instead of dying, as in lines carrying early alleles. Thus, these alleles improved Floret fertility mainly through reducing the rate of Floret mortality with no influence on the dynamics of Floret primordia initiation or in maximum number of Floret primordia. Therefore, Eps genes could be exploited in wheat breeding not only to fine-tune time to anthesis but also to improve spike fertility.
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dynamics of Floret initiation death determining spike fertility in wheat as affected by ppd genes under field conditions
Journal of Experimental Botany, 2018Co-Authors: Paula Prieto, Simon Griffiths, Roxana Savin, Helga Ochagavia, Gustavo A. SlaferAbstract:As wheat yield is linearly related to grain number, understanding the physiological determinants of the number of fertile Florets based on Floret development dynamics due to the role of the particular genes is relevant. The effects of photoperiod genes on dynamics of Floret development are largely ignored. Field experiments were carried out to (i) characterize the dynamics of Floret primordia initiation and degeneration and (ii) to determine which are the most critical traits of such dynamics in establishing genotypic differences in the number of fertile Florets at anthesis in near isogenic lines (NILs) carrying photoperiod-insensitive alleles. Results varied in magnitude between the two growing seasons, but in general introgression of Ppd-1a alleles reduced the number of fertile Florets. The actual effect was affected not only by the genome and the doses but also by the source of the alleles. Differences in the number of fertile Florets were mainly explained by differences in the Floret generation/degeneration dynamics, and in most cases associated with Floret survival. Manipulating photoperiod insensitivity, unquestionably useful for changing flowering time, may reduce spike fertility but much less than proportionally to the change in duration of development, as the insensitivity alleles did increase the rate of Floret development.
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genotypic variation in spike fertility traits and ovary size as determinants of Floret and grain survival rate in wheat
Journal of Experimental Botany, 2016Co-Authors: Zifeng Guo, Gustavo A. Slafer, Thorsten SchnurbuschAbstract:Spike fertility traits are critical attributes for grain yield in wheat (Triticum aestivum L.). Here, we examine the genotypic variation in three important traits: maximum number of Floret primordia, number of fertile Florets, and number of grains. We determine their relationship in determining spike fertility in 30 genotypes grown under two contrasting conditions: field and greenhouse. The maximum number of Floret primordia per spikelet (MFS), fertile Florets per spikelet (FFS), and number of grains per spikelet (GS) not only exhibited large genotypic variation in both growth conditions and across all spikelet positions studied, but also displayed moderate levels of heritability. FFS was closely associated with Floret survival and only weakly related to MFS. We also found that the post-anthesis process of grain set/abortion was important in determining genotypic variation in GS; an increase in GS was mainly associated with improved grain survival. Ovary size at anthesis was associated with both Floret survival (pre-anthesis) and grain survival (post-anthesis), and was thus believed to 'connect' the two traits. In this work, proximal Florets (i.e. the first three Florets from the base of a spikelet: F1, F2, and F3) produced fertile Florets and set grains in most cases. The ovary size of more distal Florets (F4 and beyond) seemed to act as a decisive factor for grain setting and effectively reflected pre-anthesis Floret development. In both growth conditions, GS positively correlated with ovary size of Florets in the distal position (F4), suggesting that assimilates allocated to distal Florets may play a critical role in regulating grain set.
Daniel J. Miralles - One of the best experts on this subject based on the ideXlab platform.
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more fertile Florets and grains per spike can be achieved at higher temperature in wheat lines with high spike biomass and sugar content at booting
Functional Plant Biology, 2014Co-Authors: Fernanda M Dreccer, Matthew P Reynolds, Kimberley Wockner, Jairo A Palta, Lynne C Mcintyre, Gabriela M Borgognone, Maryse Bourgault, Daniel J. MirallesAbstract:An understanding of processes regulating wheat Floret and grain number at higher temperatures is required to better exploit genetic variation. In this study we tested the hypothesis that at higher temperatures, a reduction in Floret fertility is associated with a decrease in soluble sugars and this response is exacerbated in genotypes low in water soluble carbohydrates (WSC). Four recombinant inbred lines contrasting for stem WSC were grown at 20/10 degrees C and 11 h photoperiod until terminal spikelet, and then continued in a factorial combination of 20/10 degrees C or 28/14 degrees C with 11 h or 16 h photoperiod until anthesis. Across environments, High WSC lines had more grains per spike associated with more Florets per spike. The number of fertile Florets was associated with spike biomass at booting and, by extension, with glucose amount, both higher in High WSC lines. At booting, High WSC lines had higher fixed C-13 and higher levels of expression of genes involved in photosynthesis and sucrose transport and lower in sucrose degradation compared with Low WSC lines. At higher temperature, the intrinsic rate of Floret development rate before booting was slower in High WSC lines. Grain set declined with the intrinsic rate of Floret development before booting, with an advantage for High WSC lines at 28/14 degrees C and 16 h. Genotypic and environmental action on Floret fertility and grain set was summarised in a model.
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Wheat Floret survival as related to pre-anthesis spike growth
Journal of Experimental Botany, 2011Co-Authors: Fernanda G. González, Daniel J. Miralles, Gustavo A. SlaferAbstract:Further improvements to wheat yield potential will be essential to meet future food demand. As yield is related to the number of fertile Florets and grains, an understanding of the basis of their generation is instrumental to raising yield. Based on (i) a strong positive association between the number of fertile Florets or grains and spike dry weight at anthesis; and (ii) the finding that Floret death occurs when spikes grow at maximum rate, it was always assumed that Floret survival depends on the growth of the spike. However, this assumption was recently questioned, suggesting that assimilates diverted to the spike do not determine the number of Florets and grains and that the onset of Floret death may instead be a developmental process that is not associated with spike growth. In this study, the relationships between the fate of Floret primordia and spike growth from six independent experiments that included different growing conditions (greenhouse/field experiments, growing seasons, photoperiod/shading treatments during the Floret primordia phase) and diverse cultivar types (winter/spring, semi-dwarf/standard-height, photoperiod sensitive/insensitive) were re-analysed together. Onset of Floret death was associated with the beginning of spike growth at the maximum rate in c. 80% of the cases analysed; and the rate of Floret death (the main determinant of Floret survival) showed a negative quantitative relationship with spike weight at anthesis. As Floret death and survival were shown to be linked to pre-anthesis spike growth, the strategy of focusing on traits associated with pre-anthesis spike growth when breeding to increase wheat yield potential further is valuable.
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nitrogen and radiation effects during the active spike growth phase on Floret development and biomass partitioning in 2 and 6 rowed barley isolines
Crop & Pasture Science, 2010Co-Authors: Sebastian Arisnabarreta, Daniel J. MirallesAbstract:The paramount importance of accumulated biomass in active-growing spikes over the number of grains per unit area has been well documented. However, it is not clear how different nitrogen (N) and radiation supplies during the active spike-growth phase alter the dynamics of Floret primordia initiation and survival to establish the number of fertile Florets and grains in 2- and 6-rowed barley. The objective of this paper was to evaluate how biomass and N partitioned between vegetative and reproductive organs alter the development of potential grains (i.e. Floret primordia), when 2- and 6-rowed barley is grown under different radiation and N levels during their active spike-growth phase. A field experiment was carried out using two near-isogenic lines differing in the spike type and grown under contrasting radiation and N levels around the active spike-growth phase. Floret primordia development and biomass and N partitioning towards vegetative and reproductive organs were analysed. The results showed significant genotype × radiation × N level interactions on the dynamics of generation and abortion of reproductive structures. Under non-limiting N conditions, reductions in radiation levels strongly reduced the number of differentiated Florets, although the effects were higher in 6- than in 2-rowed barley types. The higher the N supply, the higher the Floret development stage reached when the spikes started growing at their maximum growth rates, increasing Floret survival in that way. A threshold of floral development could not be found at any time in the crop cycle that guaranteed a fertile Floret stage at heading. As it was not possible to identify a direct effect of N on the establishment of fertile Florets, the efforts for further rising yield potential in barley should be focused on processes influencing partitioning of assimilates to reproductive growth during the critical period.
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autophagy regulated by day length determines the number of fertile Florets in wheat
Plant Journal, 2008Co-Authors: Hernan Ghiglione, Roman Augusto Serrago, Sara Maldonado, Charles Chilcott, Jose A Cura, Tong Zhu, Fernanda G. González, Daniel J. Miralles, Jorge J CasalAbstract:The wheat spikelet meristem differentiates into up to 12 Floret primordia, but many of them fail to reach the fertile Floret stage at anthesis. We combined microarray, biochemical and anatomical studies to investigate Floret development in wheat plants grown in the field under short or long days (short days extended with low-fluence light) after all the spikelets had already differentiated. Long days accelerated spike and Floret development and greening, and the expression of genes involved in photosynthesis, photoprotection and carbohydrate metabolism. These changes started while the spike was in the light-depleted environment created by the surrounding leaf sheaths. Cell division ceased in the tissues of distal Florets, which interrupted their normal developmental progression and initiated autophagy, thus decreasing the number of fertile Florets at anthesis. A massive decrease in the expression of genes involved in cell proliferation, a decrease in soluble carbohydrate levels, and an increase in the expression of genes involved in programmed cell death accompanied anatomical signs of cell death, and these effects were stronger under long days. We propose a model in which developmentally generated sugar starvation triggers Floret autophagy, and long days intensify these processes due to the increased carbohydrate consumption caused by the accelerated plant development. © 2008 The Authors.
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radiation effects on potential number of grains per spike and biomass partitioning in two and six rowed near isogenic barley lines
Field Crops Research, 2008Co-Authors: Sebastian Arisnabarreta, Daniel J. MirallesAbstract:Abstract The critical period for yield determination in barley ( Hordeum vulgare L.) is situated in the pre-heading phases. During the latest part of the critical period one of the most important yield components (i.e. the number of grains per spike) is set in two- and six-rowed barley. In wheat, much is known about the role of the spike in assimilate acquisition for the establishment of grains per spike, but not in barley. This paper evaluates how biomass partitioning between vegetative and reproductive organs impacts Floret development and primordia survival in response to radiation during different periods in the crop cycle, in barley lines. Field experiments were carried out using two- and six-rowed near isogenic barley lines differing only in spike type. Shading treatments were applied at different periods during the crop cycle (from 60 to 15 days before and after heading) reducing the intercepted radiation (ca. 70%). Dynamics of Floret primordia initiation and mortality and of Floret development for different spikelet positions along the spike were measured, and biomass partitioning between vegetative and reproductive structures was calculated. Pre-heading shading reduced fertile Florets per spike ( P The amount of assimilates partitioned to the spike at heading affected the number of fertile Florets per spike in both barley types. However, when spike biomass at heading was corrected by nitrogen concentration, the fitness of the relationship did not improve in relation to the first one. In relative terms, radiation restrictions during the immediate pre-heading phase increased the amount of biomass partitioned to the growing spike.
Roxana Savin - One of the best experts on this subject based on the ideXlab platform.
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Floret development and spike fertility in wheat differences between cultivars of contrasting yield potential and their sensitivity to photoperiod and soil n
Field Crops Research, 2020Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Abstract In a previous paper (Field Crops Res. 203, 114–127), we showed that the difference in yield potential between a contemporary and a traditional cultivar was due to differences in fruiting efficiency, likely derived from differences in spike fertility (fertile Florets per spike) while having similar spike dry weights at anthesis. In this study, we determined the mechanistic bases of these genotypic differences in spike fertility analysing the initiation of all Floret primordia per spike (up to 8), the maximum number of Florets initiated per spikelet, and the associated Floret developmental rates and their fate to become fertile Florets under contrasting photoperiod (natural vs extended) and nitrogen availability (50 or 200 kg N ha−1) during the stem elongation phase. Under potential growing conditions (natural photoperiod, high nitrogen availability), the contemporary cultivar owed its higher spike fertility to the improved rate of Floret development, which mainly determined an improved level of Floret primordia survival to produce fertile Florets. The sensitivity of the Floret developmental patterns to faster development due to exposure to an extended photoperiod and, to a larger extent, a reduction in N availability was similar for both cultivars, providing a basis for the consistent differences in spike fertility across a range of environments. The response again determined a main effect through increasing Floret mortality reducing therefore the level of fertile Florets per spikelet in these conditions.
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physiological determinants of fertile Floret survival in wheat as affected by earliness per se genes under field conditions
European Journal of Agronomy, 2018Co-Authors: Paula Prieto, Simon Griffiths, Roxana Savin, Helga Ochagavia, Gustavo A. SlaferAbstract:Abstract Variations in wheat yield are largely explained by changes in grain number per m2 which is linked to the number of fertile Florets at anthesis. This, in turn is the outcome of developmental processes which control Floret initiation and mortality. Earliness ‘per se’ (Eps) genes are involved in fine-tuning time to anthesis in wheat (and other cereals) but their effect on development prior to anthesis is less well studied. We aimed to determine effects of Eps genes on spike fertility, quantifying aspects of Floret developmental which influence this trait. Field experiments were carried out to record Floret primordia generation/degeneration dynamics in near isogenic lines (NILs) with contrasting Eps alleles (late flowering vs early flowering alleles; Eps-late and Eps-early, respectively) derived from the Avalon x Cadenza (AxC) cross with the Eps gene on either chromosome 1D or 3 A and from the Spark x Rialto (SxR) cross with the Eps gene on chromosome 1D. Eps NILs varied in spike fertility: Eps-late alleles increased fertility. Although the effect was in general slight, the magnitude was affected by the particular alleles and the cross used to produce the NILs. Differences in the number of fertile Florets were explained by differences in the dynamics of Floret development. NILs with Eps-late alleles improved the development of a small number of labile Florets allowing them to complete their development to become fertile Florets instead of dying, as in lines carrying early alleles. Thus, these alleles improved Floret fertility mainly through reducing the rate of Floret mortality with no influence on the dynamics of Floret primordia initiation or in maximum number of Floret primordia. Therefore, Eps genes could be exploited in wheat breeding not only to fine-tune time to anthesis but also to improve spike fertility.
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dynamics of Floret initiation death determining spike fertility in wheat as affected by ppd genes under field conditions
Journal of Experimental Botany, 2018Co-Authors: Paula Prieto, Simon Griffiths, Roxana Savin, Helga Ochagavia, Gustavo A. SlaferAbstract:As wheat yield is linearly related to grain number, understanding the physiological determinants of the number of fertile Florets based on Floret development dynamics due to the role of the particular genes is relevant. The effects of photoperiod genes on dynamics of Floret development are largely ignored. Field experiments were carried out to (i) characterize the dynamics of Floret primordia initiation and degeneration and (ii) to determine which are the most critical traits of such dynamics in establishing genotypic differences in the number of fertile Florets at anthesis in near isogenic lines (NILs) carrying photoperiod-insensitive alleles. Results varied in magnitude between the two growing seasons, but in general introgression of Ppd-1a alleles reduced the number of fertile Florets. The actual effect was affected not only by the genome and the doses but also by the source of the alleles. Differences in the number of fertile Florets were mainly explained by differences in the Floret generation/degeneration dynamics, and in most cases associated with Floret survival. Manipulating photoperiod insensitivity, unquestionably useful for changing flowering time, may reduce spike fertility but much less than proportionally to the change in duration of development, as the insensitivity alleles did increase the rate of Floret development.
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is Floret primordia death triggered by Floret development in durum wheat
Journal of Experimental Botany, 2013Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Survival of Floret primordia initiated seems critical for the determination of grain number and yield in wheat, and understanding what determines Floret mortality would help in the development of more robust physiological models of yield determination. The growth of the juvenile spikes has been frequently considered the determinant of grain number, implying that Floret development would depend on resource availability and that the onset of Floret death would be related to spike growth. However, this model has been recently challenged from a study concluding that Floret death started when the most advanced Floret primordia reached a particular developmental stage. As the few previous studies on this relationship involved photoperiod treatments which affect both Floret development and the onset of spike growth, conclusions cannot be considered mechanistic. This comprehensive study analysed in detail Floret development in wheat as affected by resource availability (mainly soil nitrogen levels) and found that the onset of Floret death may occur when development of the most advanced Florets ranged from stages 5 to 9 and that the average and standard deviation of Floret developmental stage coinciding with the onset of Floret death was not related to the level of availability of resources. These results provide further support to the model relating the onset of Floret death with the initiation of active growth of the juvenile spike in which Florets are developing.
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Floret development and grain setting differences between modern durum wheats under contrasting nitrogen availability
Journal of Experimental Botany, 2013Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Wheat yield depends on the number of grains per square metre, which in turn is related to the number of fertile Florets at anthesis. The dynamics of Floret generation/degeneration were studied in contrasting conditions of nitrogen (N) and water availability of modern, well-adapted, durum wheats in order to understand further the bases for grain number determination. Experiments were carried out during the 2008–2009 and 2009–2010 growing seasons at Lleida (NE Spain). The first experiment involved four cultivars (Claudio, Donduro, Simeto, and Vitron) and two contrasting N availabilities (50 kgN ha–1 and 250 kgN ha–1; N50 and N250) while experiment 2 included the two cultivars most contrasting in grain setting responsiveness to N in experiment 1, and two levels of N (N50 and N250), under irrigated (IR) and rainfed (RF) conditions. In addition, a detillering treatment was imposed on both cultivars under the IR+N250 condition. The number of fertile Florets at anthesis was increased by ~30% in response to N fertilization (averaging across treatments and spikelet positions). The effect of N and water availability was evident on Floret developmental rates from the third Floret primordium onwards, as these Florets in the central spikelets of all genotypes reached the stage of a fertile Floret in N250 while in N50 they did not. In this study, clear differences were found between the cultivars in their responsiveness to N by producing more fertile Florets at anthesis (through accelerating developmental rates of Floret primordia), by increasing the likelihood of particular grains to be set, or by both traits.
Ariel Ferrante - One of the best experts on this subject based on the ideXlab platform.
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Floret development and spike fertility in wheat differences between cultivars of contrasting yield potential and their sensitivity to photoperiod and soil n
Field Crops Research, 2020Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Abstract In a previous paper (Field Crops Res. 203, 114–127), we showed that the difference in yield potential between a contemporary and a traditional cultivar was due to differences in fruiting efficiency, likely derived from differences in spike fertility (fertile Florets per spike) while having similar spike dry weights at anthesis. In this study, we determined the mechanistic bases of these genotypic differences in spike fertility analysing the initiation of all Floret primordia per spike (up to 8), the maximum number of Florets initiated per spikelet, and the associated Floret developmental rates and their fate to become fertile Florets under contrasting photoperiod (natural vs extended) and nitrogen availability (50 or 200 kg N ha−1) during the stem elongation phase. Under potential growing conditions (natural photoperiod, high nitrogen availability), the contemporary cultivar owed its higher spike fertility to the improved rate of Floret development, which mainly determined an improved level of Floret primordia survival to produce fertile Florets. The sensitivity of the Floret developmental patterns to faster development due to exposure to an extended photoperiod and, to a larger extent, a reduction in N availability was similar for both cultivars, providing a basis for the consistent differences in spike fertility across a range of environments. The response again determined a main effect through increasing Floret mortality reducing therefore the level of fertile Florets per spikelet in these conditions.
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is Floret primordia death triggered by Floret development in durum wheat
Journal of Experimental Botany, 2013Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Survival of Floret primordia initiated seems critical for the determination of grain number and yield in wheat, and understanding what determines Floret mortality would help in the development of more robust physiological models of yield determination. The growth of the juvenile spikes has been frequently considered the determinant of grain number, implying that Floret development would depend on resource availability and that the onset of Floret death would be related to spike growth. However, this model has been recently challenged from a study concluding that Floret death started when the most advanced Floret primordia reached a particular developmental stage. As the few previous studies on this relationship involved photoperiod treatments which affect both Floret development and the onset of spike growth, conclusions cannot be considered mechanistic. This comprehensive study analysed in detail Floret development in wheat as affected by resource availability (mainly soil nitrogen levels) and found that the onset of Floret death may occur when development of the most advanced Florets ranged from stages 5 to 9 and that the average and standard deviation of Floret developmental stage coinciding with the onset of Floret death was not related to the level of availability of resources. These results provide further support to the model relating the onset of Floret death with the initiation of active growth of the juvenile spike in which Florets are developing.
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Floret development and grain setting differences between modern durum wheats under contrasting nitrogen availability
Journal of Experimental Botany, 2013Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:Wheat yield depends on the number of grains per square metre, which in turn is related to the number of fertile Florets at anthesis. The dynamics of Floret generation/degeneration were studied in contrasting conditions of nitrogen (N) and water availability of modern, well-adapted, durum wheats in order to understand further the bases for grain number determination. Experiments were carried out during the 2008–2009 and 2009–2010 growing seasons at Lleida (NE Spain). The first experiment involved four cultivars (Claudio, Donduro, Simeto, and Vitron) and two contrasting N availabilities (50 kgN ha–1 and 250 kgN ha–1; N50 and N250) while experiment 2 included the two cultivars most contrasting in grain setting responsiveness to N in experiment 1, and two levels of N (N50 and N250), under irrigated (IR) and rainfed (RF) conditions. In addition, a detillering treatment was imposed on both cultivars under the IR+N250 condition. The number of fertile Florets at anthesis was increased by ~30% in response to N fertilization (averaging across treatments and spikelet positions). The effect of N and water availability was evident on Floret developmental rates from the third Floret primordium onwards, as these Florets in the central spikelets of all genotypes reached the stage of a fertile Floret in N250 while in N50 they did not. In this study, clear differences were found between the cultivars in their responsiveness to N by producing more fertile Florets at anthesis (through accelerating developmental rates of Floret primordia), by increasing the likelihood of particular grains to be set, or by both traits.
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Floret development of durum wheat in response to nitrogen availability
Journal of Experimental Botany, 2010Co-Authors: Ariel Ferrante, Roxana Savin, Gustavo A. SlaferAbstract:In Mediterranean durum wheat production, nitrogen (N) fertilization may be important to stabilize and increase yields. Wheat yield responses to N fertilization are usually related to grains per m(2), which in turn is the consequence of processes related to Floret development (Floret initiation followed by Floret death/survival) during stem elongation. The literature is rather scarce in terms of the relevance of Floret developmental dynamics, determining the final number of grains in general terms and in particular regarding responsiveness to N. The aim of this study was to determine whether durum wheat responses to N under different water regimes are related to the dynamics of development of Floret primordia to produce fertile Florets. During the 2006-2007 and 2007-2008 growing seasons, experiments with a factorial combination of two N levels (0 and 100 or 250 kg N ha(-1)) and two levels of water availability (rainfed and irrigated) were carried out (although the water regime was only effective in the second season). The response of yield was largely a consequence of that in grain number per spike. Floret initiation was similar for both N levels in each experiment and water regime, for which the survival of a higher proportion of initiated Florets was critical in the response of the crop. The diminished rate of Floret abortion during the late part of stem elongation in response to N was associated with a slightly accelerated rate of Floret development which allowed a higher proportion of the primordia initiated to reach the stage of fertile Floret by flowering.
Sebastian Arisnabarreta - One of the best experts on this subject based on the ideXlab platform.
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nitrogen and radiation effects during the active spike growth phase on Floret development and biomass partitioning in 2 and 6 rowed barley isolines
Crop & Pasture Science, 2010Co-Authors: Sebastian Arisnabarreta, Daniel J. MirallesAbstract:The paramount importance of accumulated biomass in active-growing spikes over the number of grains per unit area has been well documented. However, it is not clear how different nitrogen (N) and radiation supplies during the active spike-growth phase alter the dynamics of Floret primordia initiation and survival to establish the number of fertile Florets and grains in 2- and 6-rowed barley. The objective of this paper was to evaluate how biomass and N partitioned between vegetative and reproductive organs alter the development of potential grains (i.e. Floret primordia), when 2- and 6-rowed barley is grown under different radiation and N levels during their active spike-growth phase. A field experiment was carried out using two near-isogenic lines differing in the spike type and grown under contrasting radiation and N levels around the active spike-growth phase. Floret primordia development and biomass and N partitioning towards vegetative and reproductive organs were analysed. The results showed significant genotype × radiation × N level interactions on the dynamics of generation and abortion of reproductive structures. Under non-limiting N conditions, reductions in radiation levels strongly reduced the number of differentiated Florets, although the effects were higher in 6- than in 2-rowed barley types. The higher the N supply, the higher the Floret development stage reached when the spikes started growing at their maximum growth rates, increasing Floret survival in that way. A threshold of floral development could not be found at any time in the crop cycle that guaranteed a fertile Floret stage at heading. As it was not possible to identify a direct effect of N on the establishment of fertile Florets, the efforts for further rising yield potential in barley should be focused on processes influencing partitioning of assimilates to reproductive growth during the critical period.
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radiation effects on potential number of grains per spike and biomass partitioning in two and six rowed near isogenic barley lines
Field Crops Research, 2008Co-Authors: Sebastian Arisnabarreta, Daniel J. MirallesAbstract:Abstract The critical period for yield determination in barley ( Hordeum vulgare L.) is situated in the pre-heading phases. During the latest part of the critical period one of the most important yield components (i.e. the number of grains per spike) is set in two- and six-rowed barley. In wheat, much is known about the role of the spike in assimilate acquisition for the establishment of grains per spike, but not in barley. This paper evaluates how biomass partitioning between vegetative and reproductive organs impacts Floret development and primordia survival in response to radiation during different periods in the crop cycle, in barley lines. Field experiments were carried out using two- and six-rowed near isogenic barley lines differing only in spike type. Shading treatments were applied at different periods during the crop cycle (from 60 to 15 days before and after heading) reducing the intercepted radiation (ca. 70%). Dynamics of Floret primordia initiation and mortality and of Floret development for different spikelet positions along the spike were measured, and biomass partitioning between vegetative and reproductive structures was calculated. Pre-heading shading reduced fertile Florets per spike ( P The amount of assimilates partitioned to the spike at heading affected the number of fertile Florets per spike in both barley types. However, when spike biomass at heading was corrected by nitrogen concentration, the fitness of the relationship did not improve in relation to the first one. In relative terms, radiation restrictions during the immediate pre-heading phase increased the amount of biomass partitioned to the growing spike.
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Floret development and grain setting in near isogenic two and six rowed barley lines hordeum vulgare l
Field Crops Research, 2006Co-Authors: Sebastian Arisnabarreta, Daniel J. MirallesAbstract:Abstract Although Floret abortion is related to a shortage in assimilates acquisition by the spikes, differences in Floret abortion and grain setting has been reported between two- and six-rowed barley types. However, the origin of those differences has not been studied until now. This study was designed to explore the dynamics of Floret development and to analyze the coordination between Floret primordia development and growth of vegetative and reproductive organs in near isogenic barley lines differing only in the lateral spikelet fertility gene (Vrs1). Two field experiments using four near isogenic lines differing only in the spike type were carried out. Floret primordia development together with stem and spike growth were studied. In both barley types Floret primordia mortality starts at the beginning of the spike active growth phase and continued when stem and spike growth were at their maximum rate. A reduced contribution of fertile Florets in apical and basal spikelet positions explained the lower Floret survival in six-rowed barleys. The chance to reach the fertile Floret stage at heading was highly dependent on the floral development stage attained at the start of Floret primordia mortality. Floret development stage at the beginning of active Floret primordia mortality was higher for all spikelet positions in two- than six-rowed barleys. Grain setting was lower in six- than two-rowed genotypes associated to a lower grain setting in distal spikelet positions. Smaller carpels in six- than two-rowed genotypes in those positions could be associated with a reduce chance of those Florets to set grains. The lower grain survival within the spike in six-rowed genotypes was caused by (i) a lower Floret survival due to a lower degree of Floret development in distal and lateral spikelet positions at the beginning of the Floret primordia mortality stage and (ii) a reduced establishment of the fertile Florets initially formed.