Michael Dingkuhn

Cirad - La recherche agronomique pour le développement | CIRAD · Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD)

Acevedo-Siaca et al. (2021) reported that A max (at saturating CO 2) is more heritable than A sat (at ambient CO 2) in rice and suggested the former to be selected to improve photosynthesis under rising ambient [CO 2 ] levels. This commentary hypothesizes sink limitation to be a factor contributing to low genotypic A max via feedback inhibition (ac...

Breeding for improved leaf photosynthesis is considered as a viable approach to increase crop yield. Whether it should be improved in combination with other traits has not been assessed critically. Based on the quantitative crop model GECROS that inter-connects various traits to crop productivity, we review natural variation in relevant traits, fro...

The ability of crop models to decompose complex traits and integrate the underlying processes enables them to capture genotype-environment interactions in diverse environments. Integrating genomics with biophysical crop models represents a potential breakthrough technology for improving our understanding of genotype-environment interactions across...

This study presents a comprehensive study of the genetic bases controlling variation in the rice ionome employing genome-wide association studies (GWAS) with a diverse panel of indica accessions, each genotyped with 5.2 million markers. GWAS was performed for twelve elements including B, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, and Zn and four agronom...

This study presents a comprehensive study of the genetic bases controlling variation in the rice ionome employing genome-wide association studies (GWAS) with a diverse panel of indica accessions, each genotyped with 5.2 million markers. GWAS was performed for twelve elements including B, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, and Zn and four agronom...

Atmospheric CO2 concentration [CO2] has increased from 260 to 280 μmol mol⁻¹ (level during crop domestication up to the industrial revolution) to currently 400 and will reach 550 μmol mol⁻¹ by 2050. C3 crops are expected to benefit from elevated [CO2] (e-CO2) thanks to photosynthesis responsiveness to [CO2] but this may require greater sink capacit...

This study aimed to understand the response of photosynthesis and growth to e‐CO2 conditions (800 vs. 400 μmol mol−1) of rice genotypes differing in source–sink relationships. A proxy trait called local C source–sink ratio was defined as the ratio of flag leaf area to the number of spikelets on the corresponding panicle, and five genotypes differin...

Lodging is a major yield-reducing factor in rice systems, particularly under intensified cultivation using high-yielding cultivars. It is usually triggered by rainstorms during grain filling. The study of natural lodging is difficult due to unpredictable weather. Proxy traits for lodging resistance such as stem morphology and breaking moment have l...

This study aimed to understand the response of photosynthesis and growth to e-CO 2 conditions (800 vs. 400 μmol mol ⁻¹ ) of rice genotypes differing in source-sink relationships. A proxy trait called local C source-sink ratio was defined as the ratio of flag leaf area over the number of spikelets on the corresponding panicle, and five genotypes dif...

This study aimed to understand the physiological bases of rice photosynthesis response to C source-sink imbalances, with focus on dynamics of the photosynthetic parameter TPU (Triose Phosphate Utilization). A dedicated experiment was replicated twice on IR64 indica rice cultivar in controlled environments. Plants were grown under the current ambien...

This study aimed to understand the physiological bases of rice photosynthesis response to C source-sink imbalances, with focus on dynamics of the photosynthetic parameter TPU (Triose Phosphate Utilization). A dedicated experiment was replicated twice on IR64 indica rice cultivar in controlled environments. Plants were grown under the current ambien...

Mali is a Sahelian country with a large climatic contrast from North to South. The current climatic and production evolutionary study is focused on the six major agro-climatic cereal production zones ranging from Kayes (400 mm) to Sikasso (>1000 mm) of rainfalls. Climatic data are rainfall records, daily maximum and minimum temperatures from 60 yea...

Les chercheurs de l'Initiative "4 pour 1000" réunis à Sète les 7 et 8 novembre 2018 lors de l’atelier "La recherche française autour du programme international de recherche de l’initiative 4 pour 1000 : les sols pour la sécurité alimentaire et le climat" ont lancé un appel pour un "programme scientifique ambitieux" pour la mise en œuvre du volet re...

Grain-filling duration (GFD) is a crucial determinant of grain yield in rice. Genotypes with longer GFD would benefit from more accumulation of assimilates by current photosynthesis, thereby optimizing yields. The current method of sampling panicles at regular intervals, separating the grains, and drying to determine GFD is tedious, laborious, time...

Background Ferrous iron (Fe) and zinc (Zn) at high concentration in the soil cause heavy metal toxicity and greatly affect rice yield and quality. To improve rice production, understanding the genetic and molecular resistance mechanisms to excess Fe and Zn in rice is essential. Genome-wide association study (GWAS) is an effective way to identify lo...

Phenology and time of flowering are crucial determinants of rice adaptation to climate variation. A previous study characterized flowering responses of 203 diverse indica rices (the ORYTAGE panel) to ten environments in Senegal (six sowing dates) and Madagascar (two years and two altitudes) under irrigation in the field. This study used the physiol...

Low night and high day temperatures during sensitive reproductive stages cause spikelet sterility in rice. Phenotyping of tolerance traits in the field is difficult because of temporal interactions with phenology and organ temperature differing from ambient. Physiological models can be used to separate these effects. A 203-accession indica rice div...

Elucidating the genetic control of rooting behaviour under water-deficit stress is essential to breed climate-robust rice cultivars. Using a diverse panel of 274 indica genotypes grown under control and water-deficit conditions during vegetative growth, we phenotyped 35 traits, mostly related to root morphology and anatomy, involving ~45,000 root s...

Genome-wide association studies revealed three candidate alleles (qER1-3) that were associated with relative response of panicle weight to low density under field conditions in the Philippine. Two of these alleles were tested in 13 genotypes to clarify their biomass responses to elevated atmospheric CO2 concentration during vegetative growth in su...

Numerous studies have addressed effects of rising atmospheric CO2 concentration on rice biomass production and yield but effects on crop water use are less well understood. Irrigated rice evapotranspiration (ET) is composed of floodwater evaporation and canopy transpiration. Crop coefficient Kc (ET over potential ET, or ETo) is crop specific accord...

Modeling of Kc. A: Dynamics of mean [Kc-1] across CO2 treatments described by 3rd-order power regression, assuming Kc = 1 in the absence of crop. B: Response of mean [Kc-1] across developmental stages described by 2nd-order power regression. C: Three-dimensional surface of response of calculated Kc (Kc = 1 + Eq 1 * Eq 2) vs. the predictor variables...

Daily weather conditions in field and CO2 chambers. (XLSX)

Naturally lit, CO2 controlled growth chambers used in the study. (TIF)

Feeding the future world population requires increased crop production. Here, we investigate the intensification option of increasing production by increasing cropping intensity and choice of varieties with different crop duration. We developed a model to generate, compare and visualise opportunities for single/double/triple cropping systems consis...

Number of spikelets per panicle (NSP) is a key trait to increase yield potential in rice (O. sativa). The architecture of the rice inflorescence which is mainly determined by the length and number of primary (PBL and PBN) and secondary (SBL and SBN) branches can influence NSP. Although several genes controlling panicle architecture and NSP in rice...

Background: Panicle architectural traits in rice (branching, rachis length, spikelet number) are established between panicle initiation and heading stages. They vary among genotypes and are prone to Genotype x Environment interactions. Together with panicle number, panicle architecture determines sink-based yield potential. Numerous studies analyz...

High-yielding rice varieties (HYV) show strong compensation among sequentially developed yield components (YC). This phenotypic plasticity has adaptive value but for crop improvement, more information is needed on its effects on yield. SAMARA, a deterministic crop model predicting trait-trait and trait-environment interactions by simulating morphog...

High-yielding rice varieties (HYV) show strong phenotypic plasticity, notably in compensatory tiller production and panicle size. In a precursor study on the high-tillering cv. IR72 we showed that the plasticity is adaptive by enabling yield stability across different stand densities, and we presented and validated the functional-structural crop mo...

Increasing rice yield potential is essential to secure world food supply. The quantitative trait locus qTSN4 was reported to achieve yield increases by enhancing both source and sink capacity. Three greenhouse experiments and one field experiment in the Philippines were conducted to study near-isogenic lines (NIL) in two genetic backgrounds, subjec...

The qTSN4 was identified as rice QTL (Quantitative Traits Locus) increasing total spikelet number per panicle and flag leaf area but potentially reducing panicle number depending on the environment. So far, this trade-off was mainly observed at grain maturity and not specifically studied in details, limiting the apprehension of the agronomic intere...

The relative (NIL1-P) of IR64 background in field-IRRI under low density. Leaf number on the main tiller (A) Tiller number per plant (B) Stem length of the main tiller (C) Individual leaf area at flowering and spikelet number per panicle at maturity (D) Peduncle and internode length at maturity (E) Peduncle and internode thickness at maturity (F).

The relative (NIL-P) of IRRI146 background in GH-CNRS under control. Leaf number on the main tiller (A) Tiller number per plant (B) Stem length of the main tiller (C) Individual leaf area at flowering and spikelet number per panicle at maturity (D) Peduncle and internode length at maturity (E) Peduncle and internode thickness at maturity (F).

Relationship between plant shoot growth rate from panicle initiation (PI) to flowering (FLO) and plant grain dry weight at maturity of the parent (black symbol) and the NIL (gray symbol), in IR64 background in GH-CNRS and field trials (A) in IRRI146 background in GH-CNRS and field trials (B) in GH-CNRS in IR64 and IRRI146 backgrounds (C) in field-I...

Carbon assimilation (A) and internode starch concentration during panicle development (B) of parent (black), NIL (gray) under isolated and crowded population in GH-IRRI. The values are mean ± SE. Results of Duncan test for multiple comparisons of each genotype per treatment at 5% level are shown in the letters above the bars. n = 3.

Crop modeling in support of breeders’ decisions on selection criteria can benefit from the new global focus on phenomics because it provides new information on existing genetic diversity for useful traits. This study attempted an in silico prediction of margins for genetic improvements of early vigor (biomass produced during vegetative growth) and...

The adaptation of flowering processes to heat is crucial for maintaining yields in rice growing systems. In the Senegal River valley, high temperatures cause sterility, a situation that has prompted the development of crop management sequences and predictive models that account for the ability of plants to escape (early anthesis time), avoid (panic...

Early vigour of rice, defined as seedling capacity to accumulate shoot dry weight (SDW) rapidly, is a complex trait. It depends on a genotype propensity to assimilate, store, and/or use non-structural carbohydrates (NSC) for producing large and/or numerous leaves, involving physiological trade-offs in the expression of component traits and, possibl...

Non-structural carbohydrates (NSC) are mobile substrates for gra in filling. NSC content among genotypes affects grain yield. For this reason, it is important to have accurate estimation of NSC content in functional organs of rice. In most of the studies, samples are stored in ice and directly oven dried prior to extraction. NSC content is reduced...

Global warming causes night temperature (NT) to increase faster than day temperature in the tropics. According to crop growth models, respiration incurs a loss of 40-60% of photosynthate. The thermal sensitivity of night respiration (R n) will thus reduce biomass. Instantaneous and acclimated effects of NT on R n of leaves and seedlings of two rice...

Global warming causes night temperature (NT) to increase faster than day temperature in the tropics. According to crop growth models, respiration incurs a loss of 40–60% of photosynthate. The thermal sensitivity of night respiration (R n) will thus reduce biomass. Instantaneous and acclimated effects of NT on R n of leaves and seedlings of two rice...

L'adaptation des processus de la floraison à la chaleur dans le but de maintenir les rendements devient un enjeu majeur en riziculture. Dans la vallée du fleuve Sénégal, les augmentations de température sont source de stérilité motivent la mise au point d'itinéraires techniques et de modèles prédictifs prenant en compte la capacité de la plante à é...

Night temperature (NT) increases faster than day temperature with global warming and this may have strong implications for crop yield. One of the assumptions is the increase in night respiration and thus the increase in carbon losses over time. Some rice cultivars (indica, aus and japonica types) were grown in the field in the Philippines and in he...

Rice crop is vulnerable to abiotic stresses such as those caused by climate change. Reactive oxygen species (ROS), which are produced during normal metabolic processes or under extreme and adverse climatic conditions, cause oxidative damage in rice crops. High amounts of ROS can have deleterious effects to the cell. Rice crops have evolved mechanis...

This document describes RIDEV, a crop model simulating rice phenology and thermal-stress related spikelet sterility, based on the end-of-project report to AfricaRice (2012) which funded development of this model. The scientific basis and data are described in Julia and Dingkuhn (2012, 2013), and in more detail in the Ph. D. thesis of Cecile Julia,...

Sugar accumulation in sorghum (Sorghum bicolor (L.) Moench) stems is a complex trait that is particularly plastic in response to photoperiod. This study investigated sucrose accumulation in a sterile (no grain filling) and fertile near-isogenic line of the photoperiod-sensitive cultivar IS2848 in two greenhouse experiments. Variable phenology was i...

For oil palm, yield variation is in large part due to variation in the number of harvested bunches. Each successively-produced phytomer carries a female (productive), male or aborted inflorescence. Since phytomer development takes 3-4 years and nearly two phytomers are produced per month, many inflorescences develop in parallel but have different p...

Source/sink ratios are known to be one of the main determinants of oil palm growth and development. A long-term experiment (9 years) was conducted in Indonesia on mature oil palms subjected to continuous bunch ablation and partial defoliation treatments to artificially modify source/sink ratios. During the experiment, all harvested bunches were dis...

Sub-Saharan West Africa is a vulnerable region where a better quantification and understanding of the impact of climate change on crop yields is urgently needed. Here, we have applied the process-based crop model SARRA-H calibrated and validated over multi-year field trials and surveys at eight contrasting sites in terms of climate and agricultural...

Sub-Saharan West Africa is a vulnerable region where a better quantification and understanding of the impact of climate change on crop yields is urgently needed. Here, we have applied the process-based crop model SARRA-H calibrated and validated over multi-year field trials and surveys at eight contrasting sites in terms of climate and agricultural...

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitières

Early vigour is an important objective in rice breeding. A previous study reported strong positive effects of development rate (DR, 1/phyllochron) on early growth vigour in two rice panels. This study provided a model‐based analysis of DR effects on rice early vigour and underlying source–sink processes during exponential growth, using Ecomeristem...

Achieving early vigour, that is, rapid dry matter accumulation, is a priority in rice crop improvement, but this trait is complex and not well understood genetically and physiologically. This study tested the hypothesis that the development rate (DR) contributes to early vigour. Two diversity panels were phenotyped during vegetative stage for trait...

Background Early vigour (biomass accumulation) is a useful but complex trait in rainfed rice (Oryza sativa L). Little is known on trade-offs with drought tolerance. This study explored the relevance of (sugar) metabolic and morphogenetic traits to describe the genetic diversity of rice early vigour and its phenotypic plasticity under drought condit...

The expression of AlSAP, in rice cv. Nipponbare, enhances plant tolerance to cold, drought and salt stresses. AlSAP lines showed 100% survival rate and set seeds while control plants did not recover from the cold treatment. Under a severe drought stress treatment (fraction of transpirable soil water down to 0.1), AlSAP lines exhibited enhanced Tran...