Biology subjects

Sadras, V.

Publications and source records attributed to Sadras, V..

9 recordsLinked to original sources

bioRxiv2026

Additive Effects Dominate Legume Responses to Combined Heat and Drought Stress: A Quantitative Review

Concurrent exposure to heat and drought stress compromises legume productivity, yet their combined effects are rarely quantified systematically. We compiled a database of 18 studies covering seven legume species. From these, we extracted 929 physiological, biochemical, and yield-related traits and calculated actual-to-additive ratios to classify heat-drought interactions as antagonistic (ratio < 1), additive (ratio = 1), or synergistic (ratio > 1). Additive heat-drought relationships accounted for 59 % of all classifiable observations, 37% relationships were antagonistic, and 4% synergistic. The relationship varied with species, genotype, trait, and experimental conditions highlighting the complexity of combined abiotic stress effects. The results challenge the common assumption that concurrent stresses invariably exacerbate damage and underscore the need for more realistic, quantitatively defined stress treatments as well as frameworks that integrate trait-level responses into predictive models of crop growth and development. Our synthesis provides a quantitative foundation to understand legume phenotypes under the increasingly frequent co-occurrence of heat and drought stress and identifies research areas where further work is needed to improve insight into combined stress responses. HighlightsO_LICombined heat and drought responses were mainly additive or antagonistic. C_LIO_LIEvidence is biased toward few legumes and controlled environments. C_LIO_LIField-based, multi-species studies are needed to identify adaptive traits. C_LI

plant biology↗

bioRxiv2026

Rethinking yield stability through phenotypic plasticity and its link to modern statistical methods

In the context of advocacy for yield stability, trade-offs between yield and yield stability, the frequent lack of definitions, and the variation in methods when they are explicit, we connect two perspectives: phenotypic plasticity and factor analytics. Phenotypic plasticity brings over a century of research in developmental biology, ecology and evolution, and is gaining traction in crop science. Factor analytics is an advanced linear mixed model of multi-environment data with factor analytic variance structures for the variety-by-environment interaction effect. We (1) review phenotypic plasticity, define agronomically adaptive plasticity where varieties (or practices) consistently return superior yield (or other traits) across environments with no trade-off, and describe percentile-plasticity plots to assess the agronomic value of plasticity; (2) outline factor analytic models, and (3) link plasticity and factor analytic models mathematically and empirically. We show that phenotypic plasticity of cereal yield correlates positively with overall performance obtained from factor analytic models when plasticity is adaptive and negatively when it is maladaptive. We conclude that phenotypic plasticity contributes biological meaning to opaque analytical approaches, and that biologically grounded statistics are needed to challenge weak agronomic narratives, such as advocacy for stability that might reflect decision biases rather than critical consideration of its benefits. HighlightUncritical advocacy for crop yield stability is common. Here we advance a biological-statistical synthesis of yield stability and test theoretical predictions with actual wheat and oat yield data.

plant biology↗

bioRxiv2025

Spatial probabilistic patterns of joint heat and water stress of chickpea in Australia

Quantitative characterisation of the crop environment for breeding and agronomic applications is commonly based on the cluster analysis of isolated climate factors, such as drought and temperature. The focus on individual climate factors fails to account for both the correlations between climate factors in space and time, and the contemporary models of dynamic biological systems where multiple interacting factors simultaneously shape the crop phenotype. With a focus on chickpea in Australia, our aims are to (1) assess the associations between climate factors and actual yield measured in 578 location -years; associations are investigated on a biologically relevant developmental scale; (2) establish the spatial, probabilistic patterns of multivariate environment types at regional and continental scales; and (3) evaluate the shifts in the frequency of environment types with climate change. We identified a syndrome of hot, dry and high vapour pressure deficit with three intensities of stress classified as low, medium and high. Measured yield, in the range from failed crop to 4 t ha-1, aligned more strongly with this multivariate syndrome than with isolated climate factors, with stronger associations at regional than continental scale. The frequency of stressful environment types increased with realised climate change and was most severe in the chickpea growing heartland of central Queensland; our models show that increased frequency of stress could be partially mitigated with earlier flowering varieties. Our findings will inform chickpea agronomy, phenotyping and breeding.

physiology↗

bioRxiv2025

Scaling law links plant growth variation to grain yield in wheat stands

Growth rate, a fundamental biological trait influencing plant resource use, scales predictably with plant mass, following remarkably consistent allometric power laws shaped by biophysical constraints and natural selection. However, how these laws apply to crop plants shaped by artificial selection, and how they manifest in agronomic traits, remains undefined. Under controlled greenhouse conditions, we quantified the relationship between plant mass and growth rate in 195 European winter wheat cultivars. We uncovered genetic variation in allometry linked to plant size, where increased leaf allocation and faster development elevated allometric exponents. Phenotypic and genetic analyses revealed adaptive strategies, ranging from large, slow-growing genotypes that support reproductive initiation to small, fast-growing genotypes that enhance reproductive effort. A shared genetic basis--associated with Photoperiod response-1 (Ppd-1)--linked growth allometry in the greenhouse to genotype-by-environment interactions for grain yield in field trials. This variation in growth allometry, shaped by breeding in diverse environments, reflects strategies that enhance adaptation to weather conditions. Our findings demonstrate that growth allometry is biologically robust and agronomically important because it scales to wheat yield under diverse, realistic field conditions.

plant biology↗

bioRxiv2024

Genetic modulation of yield and phenotypic plasticity of yield in winter wheat

For winter wheat in the US Central Great Plains, phenotypic plasticity of yield is agronomically adaptive, i.e., genotypes with higher plasticity have higher yield in high yielding environments with no tradeoff in stressful, low yielding environments. Using data from variety trials conducted between 2000 and 2022 and cultivars released between 1967 and 2022, we explored time trends in phenotypic plasticity and heritability of yield. We hypothesize that i) if yield plasticity is agronomically adaptive, then newer cultivars will have higher yield plasticity; ii) heritability of yield is declining in the time series; and iii) genomic regions associated with yield depend on the environment and do not fully overlap with those associated with phenotypic plasticity of yield. Breeding for yield and agronomic adaptation increased phenotypic plasticity of yield at 0.5% year -1; broad sense heritability of yield decreased from 0.23 in 1993 to 0.15 in 2017. Genome-wide-association analysis shows genomic regions associated with yield varied between high yielding and stressful environments and were partially independent of those associated with yield plasticity. Newer cultivars have a higher frequency of alleles associated with yield and its plasticity. We discuss implications for breeding and agronomy aimed to improve wheat phenotypes.

genetics↗

bioRxiv2024

Bread and hummus: trait connectance and correlation pleiades in grain crops

Phenotypic integration has been investigated from multiple perspectives. From a developmental perspective, connectance has been defined as the level of linkage between traits. Correlation pleiades, i.e., correlations between some traits and, simultaneously, lack of correlations between these and other traits have been interpreted as the independence of certain developmental processes with respect to other processes within the organism, and as the outcome from the discrepancy between the agencies participating in the formation of the trait and the selective forces influencing its function. Here, I use two published data sets to test the variation in connectance with both trait and genotype and the existence and meaning of correlation pleiades in wheat and chickpea. Connectance varied from 0.09 to 4.2 in wheat and from 0.06 to 22.8 in chickpea, and cluster analyses revealed correlation pleiades. The frequency distribution of connectance conformed to a power law with similar slopes = -1.665 {+/-} 0.222 for wheat and -1.555 {+/-} 0.126 for chickpea, consistent with developmental self-organisation. Connectance was lower for traits with higher heritability such as seed weight, which together with the negative association between heritability and phenotypic plasticity completes a relational triangle: high connectance {Leftrightarrow} low heritability {Leftrightarrow} high phenotypic plasticity.

developmental biology↗

bioRxiv2022

Genetic basis and adaptive implications of temperature-dependent and temperature-independent effects of drought on chickpea phenology

Water deficit often hastens flowering of pulses partially because droughted plants are hotter. Separating temperature-independent and temperature-dependent effects of drought is important to understand, model and manipulate phenology genetically and agronomically. We define a new trait, drought effect on phenology (DEP = difference in flowering time between irrigated and rainfed crops), and use FST genome scan to probe for genomic regions under selection for this trait. Genomic regions overlapping for early- and late-sown crops would associate with temperature-independent effects and non-overlapping genomic regions would associate with temperature-dependent effects. Time to flowering shortened with increasing water stress quantified with carbon isotope composition. Genomic regions on chromosomes 4, 5, 7 and 8 were under selection for DEP. An overlapping region for early and late sowing on chromosome 8 revealed a temperature-independent effect with four candidate genes: BAM1, BAM2, HSL2 and ANT. The non-overlapping regions included six candidate genes: EMF1, EMF2, BRC1/TCP18, BZR1, NPGR1 and ERF1. Modelling to assess DEP adaptive value showed it reduces the likelihood of drought and heat stress at the expense of cold risk. Accounting for DEP would improve phenology models to predict adaptation to future climates and breeding against the combined risks of drought, heat, and cold stress. HighlightPredictive and genetic models that overlook drought effects on phenology can return biased predictions of adaptation to future climates. Here we study the genetic causes and adaptive consequences of hastened flowering under drought.

plant biology↗

bioRxiv2021

Carbon isotope composition for agronomic diagnostic: predicting yield and yield response to nitrogen in wheat

Rainfed crops rely on two sources of water: stored soil water at sowing and seasonal rain. In strongly seasonal winter-rainfall environments, stored soil water at sowing is minor, and uncertain seasonal rainfall is a source of risk. In south-eastern Australia, under-fertilisation is a common outcome of nitrogen risk management with implications for yield and soil mining. Here we explore the use of carbon isotope composition ({delta} 13C) to capture the effects of water in the prediction of yield and guide nitrogen management. In the sampled environment, crops receive at least 50% of seasonal rainfall by stem elongation, and at least 70% of seasonal rainfall by flowering. In a sample of 1518 plots, yield varied from 0.07 to 9.96 t ha-1 and correlated with {delta} 13C measured with isotope ratio mass spectrometer (IRMS) at flowering; this is consistent with the rainfall pattern and the physiology of the crop featuring a critical period for yield from 300 {degrees}Cd before to 100 {degrees}Cd after anthesis. In a sample of 135 plots, yield varied from 1.2 to 8.4 t ha-1 and correlated with {delta} 13C measured with IRMS at stem elongation. Yield response to nitrogen, defined as the difference between yield in fertilised crops (50 to 200 kg N ha-1) and unfertilised controls, correlated with {delta} 13C measured with IRMS at stem elongation, except for late-sown crops. Mid-infrared spectroscopy (MIR) returned estimates of {delta} 13C that agreed with {delta} 13C measured with IRMS (calibration: R2 = 0.82, RMSE = 0.53{per thousand}, n = 833; validation: R2 = 0.70, RMSE = 0.75{per thousand}, n = 364). We conclude that a MIR based, high-throughput, affordable measurement of {delta} 13C could be scaled to guide nitrogen management of wheat in winter-rainfall environments.

plant biology↗

bioRxiv2017

Hypoxia in the grape berry linked to mesocarp cell death: the role of seed respiration and lenticels on the berry pedicel

Mesocarp cell death (CD) during ripening is common in berries of seeded Vitis vinifera L wine cultivars. We examined if hypoxia within berries is linked to CD. Internal oxygen concentration ([O2]) across the mesocarp was measured in berries from Chardonnay and Shiraz, both seeded, and Ruby Seedless, using an oxygen micro-sensor. Steep [O2] gradients were observed across the skin and [O2] decreased toward the middle of the mesocarp. As ripening progressed the minimum [O2] approached zero in the seeded cultivars and correlated to CD. Seed respiration was a large proportion of total berry respiration early in ripening but did not account for O2 deficiency late in ripening. [O2] increased towards the central axis corresponding to the presence of air spaces visualised using x-ray microCT. These connect to lenticels on the pedicel that were critical for berry O2 uptake as a function of temperature, and when blocked caused anoxia in the berry, ethanol accumulation and CD. Lenticel area on Chardonnay pedicels was higher than that for Shiraz probably accounting for the lower sensitivity of Chardonnay berry CD to high temperatures. The implications of hypoxia in grape berries are discussed in terms of its role in ripening and berry water relations.\n\nHighlightGrape berry internal oxygen concentration is dependent upon lenticels on the pedicel and cultivar differences in lenticels may account for temperature sensitivity of cell death in the mesocarp.

plant biology↗