Calculating crop yields from space

Agriculture in the Khorezm region faces high production risks due to fluctuating irrigation water supply, uncertain effects of future climate change, land degradation, and management issues. New methods such as satellite-based remote sensing can support sustainable and improved land and water management in the region. In this ZUR, we present a satellite-based methodology to calculate Khorezm-wide crop yields at the field scale, which could be used to substantially improve the informational base for decision makers

Transpiration Efficiency of Some Potato Genotypes under Drought

Potato (Solanum tuberosum L.) is the third most consumed food crop after rice and wheat in the world. It is a short-duration crop, suitable for growing in a wide range of environments, but abiotic factors can limit potato production, and drought is the main one. Therefore, managing drought stress is of utmost importance under climate change conditions. Potato as a drought-sensitive crop needs choice of suitable genotypes for dry environments. In this study, transpiration efficiency (TE), soil water conservation and drought tolerance were analysed for potato genotypes from different origins. Three glasshouse experiments under different Vapor Pressure Deficit (VPD) conditions with water-stressed (WS) and well-watered (WW) plants resulted in significantly different total amounts of transpiration among the genotypes and water supply levels. Transpiration in WS plants was the same as with WW plants up to a specific threshold “Fraction of Transpirable Soil Water” (FTSW) and then sharply decreased in response to soil drying. Genotypes showed a substantial variation in FTSW thresholds (0.19 to 0.36 FTSW) under low VPD condition, which narrowed down (0.19 to 0.29) when air humidity was lower. Furthermore, we observed hardly any relationships between TE and FTSW threshold (r = 0.125) or TE and water saving (r = 0.031). Our results provide insights into genotypic interactions with VPD on FTSW threshold and TE under dry-down conditions in potato

Modelling the implications of variation in phenology and leaf canopy development for wheat adaptation to climate change

Crop models offer a great potential to quantitatively assess the impact of specific traits on crop yield and design ideotypes for target environments and future climatic conditions. The objectives of this study were to evaluate the capability of APSIM model for simulating two wheat cultivars contrasting in canopy development and phenology, and explore the implications of these traits for adaptation to climate change. A field experiment was conducted with a winter (Capo) and a facultative (Xenos) cultivar grown in Pannonian eastern Austria. Crops were sown at five sowing dates in 2013-14. Wheat yields ranged from 260 to 722 g m-2. Capo exhibited a more vigorous canopy growth and produced higher yields in autumn-sown plants, whereas Xenos performed better with spring sowing. The experimental dataset was used to parameterize the APSM model. While APSIM was capable of simulating the observed differences in phenology between the two cultivars, simulations of leaf canopy development were less accurate when the model default values for leaf appearance rate (phyllochron) and size were used. Adjusting these model parameters based on observed data improved the simulation results substantially. Thus, APSIM proved to be a robust modelling framework for capturing the differences in phenology and leaf canopy development in wheat and the resulting effects on crop water/N use and yield. The well-parameterised model was subsequently used to assess the potential value of genotypic variation in phenology and leaf canopy development for wheat adaptation to climate change by linking APSIM with climate change scenarios for the period 2035–65 in eastern Austria. The functional implications of variation in those plant traits on adaptation of wheat to future climatic conditions are discussed

Assessing the sustainability of wheat-based cropping systems using simulation modelling: sustainability

Concepts of agricultural sustainability and possible roles of simulation modelling for characterising sustainability were explored by conducting, and reflecting on, a sustainability assessment of rain-fed wheat-based systems in the Middle East and North Africa region. We designed a goal-oriented, model-based framework using the cropping systems model Agricultural Production Systems sIMulator (APSIM). For the assessment, valid (rather than true or false) sustainability goals and indicators were identified for the target system. System-specific vagueness was depicted in sustainability polygons-a system property derived from highly quantitative data-and denoted using descriptive quantifiers. Diagnostic evaluations of alternative tillage practices demonstrated the utility of the framework to quantify key bio-physical and chemical constraints to sustainability. Here, we argue that sustainability is a vague, emergent system property of often wicked complexity that arises out of more fundamental elements and processes. A 'wicked concept of sustainability' acknowledges the breadth of the human experience of sustainability, which cannot be internalised in a model. To achieve socially desirable sustainability goals, our model-based approach can inform reflective evaluation processes that connect with the needs and values of agricultural decision-makers. Hence, it can help to frame meaningful discussions, from which actions might emerge

QTL for root angle and number in a population developed from bread wheats (Triticum aestivum) with contrasting adaptation to water-limited environments

Root architecture traits in wheat are important in deep soil moisture acquisition and may be used to improve adaptation to water-limited environments. The genetic architecture of two root traits, seminal root angle and seminal root number, were investigated using a doubled haploid population derived from SeriM82 and Hartog. Multiple novel quantitative trait loci (QTL) were identified, each one having a modest effect. For seminal root angle, four QTL (-log10(P) >3) were identified on 2A, 3D, 6A and 6B, and two suggestive QTL (-log10(P) >2) on 5D and 6B. For root number, two QTL were identified on 4A and 6A with four suggestive QTL on 1B, 3A, 3B and 4A. QTL for root angle and root number did not co-locate. Transgressive segregation was found for both traits. Known major height and phenology loci appear to have little effect on root angle and number. Presence or absence of the T1BL.1RS translocation did not significantly influence root angle. Broad sense heritability (h (2)) was estimated as 50 % for root angle and 31 % for root number. Root angle QTL were found to be segregating between wheat cultivars adapted to the target production region indicating potential to select for root angle in breeding programs

The role of root architectural traits in adaptation of wheat to water-limited environments

Better understanding of root system structure and function is critical to crop improvement in water-limited environments. The aims of this study were to examine root system characteristics of two wheat genotypes contrasting in tolerance to water limitation and to assess the functional implications on adaptation to water-limited environments of any differences found. The drought tolerant barley variety, Mackay, was also included to allow inter-species comparison. Single plants were grown in large, soil-filled root-observation chambers. Root growth was monitored by digital imaging and water extraction was measured. Root architecture differed markedly among the genotypes. The drought-tolerant wheat (cv. SeriM82) had a compact root system, while roots of barley cv. Mackay occupied the largest soil volume. Relative to the standard wheat variety (Hartog), SeriM82 had a more uniform rooting pattern and greater root length at depth. Despite the more compact root architecture of SeriM82, total water extracted did not differ between wheat genotypes. To quantify the value of these adaptive traits, a simulation analysis was conducted with the cropping system model APSIM, for a wide range of environments in southern Queensland, Australia. The analysis indicated a mean relative yield benefit of 14.5% in water-deficit seasons. Each additional millimetre of water extracted during grain filling generated an extra 55 kg ha(-1) of grain yield. The functional implications of root traits on temporal patterns and total amount of water capture, and their importance in crop adaptation to specific water-limited environments, are discussed