Marie-Paule Raveneau

Flowering is a critical stage of fennel seed production, which strongly depends on climate factors. In crops such as fennel, the complexity of the umbellate structure and the lack of knowledge about its flowering dynamics make the prediction of the duration of this phenological stage uneasy. In the context of climate change, a reliable predictive tool for the duration of fennel flowering is needed. Our aim was to increase knowledge on fennel flowering dynamics and to propose a model to be used by seed producers. In 2018 and 2019, we studied the development of secondary and tertiary umbels during flowering stage which was determined from the Bundesanstalt Bundessortenamt und Chemische Industrie scale, in plants of four genotypes grown in tunnels. Multiple linear regression (MLR) models were used to select the more accurate equations which consisted of one or more variables as predictors of flowering duration and its dynamics across secondary and tertiary umbels. In all model subsets, the criterion‐based procedure was used, followed by a criterion‐based hybrid procedure to take advantage of the Mallows' Cp, adjusted R2 and Bayesian information criterion, for equations and predictor selection. Two variables related to temperature, namely the temperature summation expressed in degree days and the number of days with temperature lower than 15°C, were identified as relevant parameters for predicting flowering duration expressed in days, in secondary as well as tertiary umbels. In addition, the equations and accurate predictors identified for modelling differences in time between flowering starts and ends of secondary and tertiary umbels also highlighted the importance of the number of days when the temperature amplitude is higher than 20°C, the number of days when the mean temperature is higher than 27°C, and the number of days when the relative humidity is higher than 80%.

A non-destructive indicator of seed water content could significantly help crop scientists with assessment of the effects of environmental conditions during drying on grain qualities or on seed physiological quality. This is particularly important for grain legumes which simultaneously bear pods of different ages. Visual assessment of pod colour has so far been used to date grain legume stages, but now colour can be easily and accurately measured with a portable spectrophotometer. Relationships between the spectrophotometer measurements and the pod and seed water contents were tested in various climatic contexts (3 years: 2000, 2001, 2002; field or greenhouse, two or three sowing dates) for two bean cultivars (Booster and Calypso) and also for one pea cultivar (Baccara) in 2003 near Angers, France. Among the different spectrophotometer measurements, hue angle (h) clearly shows the transition from green (h=180 °) to yellow (h=90 °) and then to red (h=0 °). In each context, h and seed water content (SWC) relationships showed the same pattern of three linear phases: first a steady state; then a sharp decrease from green (h=106–108 °) to yellow (h=85–93 °) just before the end of the seed filling stage for Booster or between the end of the seed filling phase and the beginning of seed drying for Calypso and pea; finally, a slow decrease from yellow to ochre (h=75–78 °) during seed drying. For each bean cultivar, the parameters of the linear relationships showed no differences between maturation conditions. Therefore, 6 h classes matching six SWC classes could be defined over a wide range of SWC between 0·56 and 0·2 g/g for Booster. However for Calypso and pea, only 3 h classes could be defined because of the tight relationships between h and SWC during the end of seed drying, which can be explained by pod walls drying faster than seeds. Hence, spectrophotometer measurements, if calibrated for a given cultivar of a species, could now be used to select pods with seeds of the same water content and therefore to study environmental effects on quality criteria either in controlled conditions or in the field.

Flowering is a critical stage of fennel seed production, which strongly depends on climate factors. In crops such as fennel, the complexity of the umbellate structure and the lack of knowledge about its flowering dynamics make the prediction of the duration of this phenological stage uneasy. In the context of climate change, a reliable predictive tool for the duration of fennel flowering is needed. Our aim was to increase knowledge on fennel flowering dynamics and to propose a model to be used by seed producers. In 2018 and 2019, we studied the development of secondary and tertiary umbels during flowering stage which was determined from the Bundesanstalt Bundessortenamt und Chemische Industrie scale, in plants of four genotypes grown in tunnels. Multiple linear regression (MLR) models were used to select the more accurate equations which consisted of one or more variables as predictors of flowering duration and its dynamics across secondary and tertiary umbels. In all model subsets,...

Des semis precoces permettent d'allonger les cycles de culture du pois proteagineux et d'eviter les stress hydriques et thermiques tardifs, ce qui contribue a la maitrise des variations de rendement. Les objectifs de ce travail sont 1) d'etudier le comportement de differents genotypes de pois au cours de la germination en reponse a la temperature ; 2) de determiner l'impact des vitesses de dessiccation a temperature elevee sur les caracteristiques des graines, leur germination et leur conservation ; 3) d'explorer la reprise du metabolisme energetique et la mobilisation des sucres solubles au cours de la germination et de determiner l'impact d'une vitesse de dessiccation rapide apres la phase de remplissage et des basses temperatures pendant la germination. Les pois de printemps Baccara et Terese et le pois d'hiver Champagne presentent une temperature de base identique et tres basse de -1,1°C. Le genotype Champagne a une vitesse de germination plus rap...

Flowering is a critical stage of fennel seed production, which strongly depends on climate factors. In crops such as fennel, the complexity of the umbellate structure and the lack of knowledge about its flowering dynamics make the prediction of the duration of this phenological stage uneasy. In the context of climate change, a reliable predictive tool for the duration of fennel flowering is needed. Our aim was to increase knowledge on fennel flowering dynamics and to propose a model to be used by seed producers. In 2018 and 2019, we studied the development of secondary and tertiary umbels during flowering stage which was determined from the Bundesanstalt Bundessortenamt und Chemische Industrie scale, in plants of four genotypes grown in tunnels. Multiple linear regression (MLR) models were used to select the more accurate equations which consisted of one or more variables as predictors of flowering duration and its dynamics across secondary and tertiary umbels. In all model subsets, the criterion‐based procedure was used, followed by a criterion‐based hybrid procedure to take advantage of the Mallows' Cp, adjusted R2 and Bayesian information criterion, for equations and predictor selection. Two variables related to temperature, namely the temperature summation expressed in degree days and the number of days with temperature lower than 15°C, were identified as relevant parameters for predicting flowering duration expressed in days, in secondary as well as tertiary umbels. In addition, the equations and accurate predictors identified for modelling differences in time between flowering starts and ends of secondary and tertiary umbels also highlighted the importance of the number of days when the temperature amplitude is higher than 20°C, the number of days when the mean temperature is higher than 27°C, and the number of days when the relative humidity is higher than 80%.

A non-destructive indicator of seed water content could significantly help crop scientists with assessment of the effects of environmental conditions during drying on grain qualities or on seed physiological quality. This is particularly important for grain legumes which simultaneously bear pods of different ages. Visual assessment of pod colour has so far been used to date grain legume stages, but now colour can be easily and accurately measured with a portable spectrophotometer. Relationships between the spectrophotometer measurements and the pod and seed water contents were tested in various climatic contexts (3 years: 2000, 2001, 2002; field or greenhouse, two or three sowing dates) for two bean cultivars (Booster and Calypso) and also for one pea cultivar (Baccara) in 2003 near Angers, France. Among the different spectrophotometer measurements, hue angle (h) clearly shows the transition from green (h=180 °) to yellow (h=90 °) and then to red (h=0 °). In each context, h and seed water content (SWC) relationships showed the same pattern of three linear phases: first a steady state; then a sharp decrease from green (h=106–108 °) to yellow (h=85–93 °) just before the end of the seed filling stage for Booster or between the end of the seed filling phase and the beginning of seed drying for Calypso and pea; finally, a slow decrease from yellow to ochre (h=75–78 °) during seed drying. For each bean cultivar, the parameters of the linear relationships showed no differences between maturation conditions. Therefore, 6 h classes matching six SWC classes could be defined over a wide range of SWC between 0·56 and 0·2 g/g for Booster. However for Calypso and pea, only 3 h classes could be defined because of the tight relationships between h and SWC during the end of seed drying, which can be explained by pod walls drying faster than seeds. Hence, spectrophotometer measurements, if calibrated for a given cultivar of a species, could now be used to select pods with seeds of the same water content and therefore to study environmental effects on quality criteria either in controlled conditions or in the field.

Flowering is a critical stage of fennel seed production, which strongly depends on climate factors. In crops such as fennel, the complexity of the umbellate structure and the lack of knowledge about its flowering dynamics make the prediction of the duration of this phenological stage uneasy. In the context of climate change, a reliable predictive tool for the duration of fennel flowering is needed. Our aim was to increase knowledge on fennel flowering dynamics and to propose a model to be used by seed producers. In 2018 and 2019, we studied the development of secondary and tertiary umbels during flowering stage which was determined from the Bundesanstalt Bundessortenamt und Chemische Industrie scale, in plants of four genotypes grown in tunnels. Multiple linear regression (MLR) models were used to select the more accurate equations which consisted of one or more variables as predictors of flowering duration and its dynamics across secondary and tertiary umbels. In all model subsets,...

Des semis precoces permettent d'allonger les cycles de culture du pois proteagineux et d'eviter les stress hydriques et thermiques tardifs, ce qui contribue a la maitrise des variations de rendement. Les objectifs de ce travail sont 1) d'etudier le comportement de differents genotypes de pois au cours de la germination en reponse a la temperature ; 2) de determiner l'impact des vitesses de dessiccation a temperature elevee sur les caracteristiques des graines, leur germination et leur conservation ; 3) d'explorer la reprise du metabolisme energetique et la mobilisation des sucres solubles au cours de la germination et de determiner l'impact d'une vitesse de dessiccation rapide apres la phase de remplissage et des basses temperatures pendant la germination. Les pois de printemps Baccara et Terese et le pois d'hiver Champagne presentent une temperature de base identique et tres basse de -1,1°C. Le genotype Champagne a une vitesse de germination plus rap...