Limited Yield Potential Research Articles

Maize yields could benefit from increased vapor pressure deficit in hot managed environments

Abstract Recent studies highlight the adverse effects of increasing vapor pressure deficit (VPD) due to climate change on maize yields. Maize breeders are utilizing available genetic diversity to address these challenges. However, contrasting ecophysiological properties and genotype by environment interactions (GEI) often hinder these efforts. This study by the Agricultural Institute Osijek, in collaboration with Turkish company Tarım Kredi Tohumculuk, explores the adaptation of maize germplasm to hot, managed environments in Türkiye, originally bred for Southeast and Central European rainfed conditions. Over an 11-year period (2009–2019), multi-environment trials (MET) were conducted in two stages. In cycle 0 (C0), 22 hybrids were evaluated across 17 environments in Croatia and Türkiye. In cycle 1 (C1), MET was conducted in 18 Turkish environments. Complete linkage hierarchical clustering based on hybrid performance and climatic variables revealed two distinct clusters with positive or negative responses to increasing VPD in C0. In C1, genetic variances increased with rising VPD, maintaining distinct responses. Our findings align with reports on the limited transpiration trait in maize and sorghum, suggesting that while such traits can reduce water loss, they may also limit yield potential in high-VPD environments.

Historical Trends Analysis of Main Agronomic Traits in South China Inbred Indica Rice Varieties since Dwarf Breeding

Studying the evolutionary patterns of rice agronomic traits in South China and analyzing the characteristics of rice improvement can provide insights into the developmental trajectory of rice breeding in South China and can guide further enhancement of variety yield. In this study, widely promoted varieties and core parents developed through dwarf breeding in the southern region, as well as landraces, were collected and planted in three different ecological regions. A total of 18 agronomic traits were investigated related to heading date, plant type, panicle type, grain type, and yield, and multiple comparisons, a correlation analysis, and a path analysis were conducted. The results indicate that dwarf breeding has significantly increased the yield of inbred indica rice varieties in South China. However, a reduction in plant height has also resulted in a reduction in flag leaf, shorter panicles, and decreased biomass, which have led to metabolic source and storage capacity deficiencies and limited yield potential. To address these limitations, breeders have employed strategies such as increasing flag leaf width, spikelet density, number of primary branches, and grain number per panicle. These measures have led to a gradual increase in yield. Additionally, starting from the 1980s, high-quality rice breeding has been pursued in South China, resulting in slender grain shape and reduced thousand grain weight. Given that total grain number per panicle has already increased significantly and the thousand grain weight cannot be reduced further, enhancing the effective tiller number, which decreases year by year, becomes an important approach to increasing the yield of inbred indica rice varieties in South China.

Influence of a cereal rye cover crop on the critical period for weed control in soybean

AbstractSoybean is the world’s most widely grown leguminous crop and is an important source of oil and protein for food and feed in addition to other industrial uses. However, herbicide-resistant and troublesome weed control challenges limit yield potential and threaten conservation tillage (CT) systems. Cover crops have been widely adopted as an integrated pest management component in CT systems to suppress weeds and maintain soybean yield potential. A 3-yr field experiment was conducted to estimate the influence of a cereal rye cover crop following CT on the critical period for weed control (CPWC) in soybean. The experiment was implemented in a split-plot design in which main plots as CT following cover crop (CT + CC), CT following winter fallow (CT + WF), and conventional tillage (CVT), and subplots were multiple durations of weed-free and weed interference. Results showed that the estimated CPWC of CT + CC and CT + WF treatments was 0 wk and >7 wk, respectively, in 2018. In 2019, the estimated CPWC was 0 wk, 5.0 wk, and 1.3 wk under CT + CC, CT + WF, and CVT treatments, respectively. In 2020, the estimated CPWC was 3.5 wk, >6.2 wk, and 0 wk under CT + CC, CT + WF, and CVT treatments, respectively. The presence of a cover crop delayed the CTWR and caused an early beginning of the CWFP compared with CT + WF treatment, and hence shortened the CPWC in 2018 and 2019. In conclusion, the CT + WF system did not reduce the weed competition and subsequent yield loss in soybean compared to the CT + CC system.

Impact of Lime, Phosphorus, and Potassium on Yield and Forage Quality on Native Hay Meadows in Southeast Kansas

Native meadows are frequently harvested for hay in southeast Kansas to produce forage for winter use. However, the low soil fertility associated with nutrient removal has resulted in limited yield potential and broomsedge infestation. This study evaluated the effect of phosphorus, potassium, and lime on the forage yield and quality in a native meadow. Our results indicated that P and K fertilization contributes to improving yield and quality on native meadows in southeast Kansas. This study will be repeated in 2023, including broomsedge measurements.

Effect of Foliar Application of Mannitol on Growth and Yield of Maize under Different Water Regimes

Maize is an important cereal crop in world. Due to the climate change the temperature has increased and water availability is reduced. Both factors limit yield potential of major cereal crops. Uniform and vigorous stand establishment is the main milestone for economically successful maize production program, but drought stress is the major cause of stand failure and yield reduction. Mannitol is considered essential for photosynthates activity which contributes 60-80% in many plants, it produces photosynthates in leaves that are translocated in phloem. Mannitol synthesis is normal in the cytosol of source leaves with a hexose phosphate pool with sucrose synthesis. Experiment was conducted to estimate the effect of various irrigation levels I0: Control, I1: Skip Irrigation at tasseling, I2: Skip Irrigation at dough stage and foliar application of mannitol with given concentration C0: 0 mM, C1: 2 mM, C2: 4 mM, C3: 6 mM on maize variety DS-555. This experiment was conducted at Agronomic Research Area, University of Agriculture, Faisalabad. The plants were uprooted from field at emergence, tasseling, silking, milking and physiological maturity stages and subject to oven dry method to understand the plant biomass partitioning. All parameters of stand establishment, growth and yield related parameters were evaluated in laboratory. The Fisher's ANOVA analysis of variance methodology was used to statistically evaluate the measured results, and the treatment means was valuated using the Least Significance Difference (LSD) test at a 5% probability level.

The interaction between drought stress and nodule formation under multiple environments in chickpea.

Environmental stresses, particularly drought, limit symbiotic nitrogen fixation in legumes, resulting in decreased yielding capacity. Drought is one of the most important constraints limiting yield potential in crops and it is the major abiotic stress that can cause more than 70% yield loss in chickpea. In this study, a total of two hundred four chickpea (Cicer arietinum L.) genotypes were selected to study the interaction between drought stress and nodule formation. This interaction was assessed by using morphological, yield and yield components. The field experiments were laid out in two locations (Terbol and Kfardan stations, Bekaa valley, Lebanon) using Alpha lattice design with two replications and two watering treatments (irrigation and rainfed) during 2016 and 2017 seasons. Parameters that were measured include days to 50% flowering (DFL), day to maturity (DM), plant height (PLH), nodule biomass (NB), nodule fresh weight (NFW), nodule dry weight (NDW), grain yield (GY), Biological yield (BY), 100 seed weight (100SW) and drought tolerance stress (DTS). The results indicated a significant variation between genotypes, environments and other morphological, yield and yield components traits. Drought stress reduced significantly the yield and the nodule’s characteristics, biological and grain yield. The genotypes with the highest levels of drought tolerance, such as IG70399, IG8256, IG71832, IG70270, and IG70272, showed a minimal decrease in yield and nodule biomass. Nodule observations significantly and positively correlated with GY (0.36-0.38) under drought stress treatment. The correlation values for nodule characteristics with DFL and DM were higher under drought stress compared to irrigated conditions. This is a comparative study between drought stress and nodule formation traits associated with morphological, yield and yield components traits.

Root system variation of pulse crops at early vegetative stage

Grain legumes known as “Pulse crops” are economically and nutritionally one of the most important crop families after cereals. Climate change and abiotic stress factors are limiting yield potential in these crops. Root system architecture, a neglected field, is promising for improved environmental adaptability and higher growth potential. Genotypes with deep and dense root system may cope better with water and nutrient limitations. This study aimed to evaluate 12 common cultivars from six different legume species. Root system architectures were evaluated under controlled conditions in a plexiglass system at the early vegetative stage. Roots were divided into four depth zones (0, 5, 10, 15> cm), and inter and intra species diversity were analysed. Significant diversity was obtained within and between the species. Bean, chickpea, and broad bean constituted deeper and dense root systems while lentil, soybean, and pea formed non-dense and shallower root systems. There was a significant correlation between earliness and early vegetative root vigour. The results of the study may provide a better understanding of the root system architectures of each species-genera. The results presented here may shed light on the selection of root traits in legume breeding programs.

Evaluation of nitrogen bank, a soil nitrogen management strategy for sustainably closing wheat yield gaps

Yield gaps of ∼50 % of water limited yield potential occur in wheat globally. Nitrogen (N) deficiency frequently contributes to the gap, but it is difficult to predict an appropriate rate of N to apply because of uncertainty about the forthcoming season and hence water limited potential yield and crop N requirements. We investigated closing the water limited yield gap attributable to N supply by maintaining a “bank” of soil mineral N that is nonlimiting for wheat yields in most seasons. The yield, loss of NO3−-N in leaching and denitrification, and gross margins of wheat crops were simulated at four Australian locations with contrasting soil types and potential yields, in response to N inputs calculated by reference to N banks ranging from 50 to 400 kg N ha-1, the Yield Prophet® decision support tool and the national average N rate. The N bank providing best yields at each location was close in amount to the long-term average rate calculated with Yield Prophet®. Compared to the national average rate of N fertiliser application (45 kg N ha-1), the highest-yielding N bank treatment on average increased the amount of N applied by 3–234 kg N ha-1, the fraction of water limited potential yield by 0.0 to 0.61, and gross margins by AUD 0–1,026 ha-1. Combined losses of N to the environment in NO3−leaching and through denitrification in these strategies also increased but by a disproportionately small amount compared to the increase in the amount applied (-3 to 8.5 kg N ha-1). These losses were relatively insensitive to the amount of N applied at three of the four locations; at the fourth location large episodic losses could occur from sandy soil despite low rainfall when the N bank exceeded water limited potential yield. The N bank approach to determining fertiliser rate has potential to sustainably reduce the yield gap where the target amount is matched to average site-specific yield potential.

Recent changes in rice production in rainfed lowland and irrigated ecosystems in Thailand

ABSTRACT While Thailand is a major rice exporting country in the world, the yield is low among Asian countries. In order to identify factors determining the changes in rice productivity in the country for the last 45 years (1974–2018), various data on production statistics from the Office of Agricultural Economics were analysed for two key regions of rainfed lowland-based Northeast Thailand and irrigated lowland-based Central Thailand. Rice yield increase in Thailand was slower in the first 16 years to 1989, but more rapid to 2011 followed by a large fluctuation in more recent time, and this pattern reflected in the pattern of rice production in the country. The changes in rice production were partly associated with the changes in irrigation water availability affecting dry season rice area and grain yield, thus increasing total production up to 2011, but thereafter decreasing production. The changes in production were also associated with other factors such as increased fertiliser application rate in early years, proportion of modern high yielding varieties adopted in Central Thailand in early years, and continuous agronomic improvement in Northeast Thailand throughout the whole period. In Northeast Thailand where the largest rice production takes place in the country, the same varieties of high grain quality but rather limited yield potential have dominated since 1974, indicating the importance of grain quality rather than high varietal yield in determining the total rice production in the country. Government policy has appeared to have affected the production, though it is not quantified in the study.

Effect of wide-narrow row arrangement in mechanical pot-seedling transplanting and plant density on yield formation and grain quality of japonica rice

Mechanical pot-seedling transplanting is an innovatively developed transplanting method that has the potential to replace mechanical carpet-seedling transplanting. However, the initial pot-seedling transplanting machine lacked optimized density spacing and limited yield potential for japonica rice. Therefore, ascertaining the optimized density by wide-narrow rows and the appropriate transplanting method for yield formation and grain quality of japonica rice is of great importance for high-quality rice production. Field experiments were conducted using two japonica rice cultivars Nanjing 9108 and Nanjing 5055 under three transplanting methods in 2016 and 2017: mechanical pot-seedling transplanting with wide-narrow row (K, average row spacing of 30 cm); equidistant row (D, 33 cmx12 cm); and mechanical carpet-seedling transplanting (T, 30 cm×12.4 cm). In addition, five different density treatments were set in K (K1–K5, from 18.62×104 to 28.49×104 hills ha–1). The results showed that the highest yield was produced by a planting density of 26.88×104 hills ha–1 in mechanical pot-seedling transplanting with wide-narrow row with a greater number of total spikelets that resulted from significantly more panicles per area and slightly more grain number per panicle, as compared with equidistant row, and yield among density in wide-narrow row showed a parabolic trend. Compared with mechanical carpet-seedling transplanting, the treatment of the highest yield increased yield significantly, which was mainly attributed to the larger sink size with improved filled-grain percentage and grain weight, higher harvest index, and increased total dry matter accumulation, especially the larger amount accumulated from heading stage to maturity stage. With the density in wide-narrow row decreasing, processing quality, appearance quality, and nutrition quality were all improved, whereas amylose content and the taste value were decreased. Compared with mechanical carpet-seedling transplanting, mechanical pot-seedling transplanting improved processing quality and nutrition quality, but decreased amylose content and deteriorated appearance quality. These results suggested that mechanical pot-seedling transplanting with wide-narrow row coupling produced a suitable planting density of 26.88×104 hills ha–1 and may be an alternative approach to improving grain yield and quality for japonica rice.

Frost Risk Management in Chickpea Using a Modelling Approach

Post-flowering frosts cause appreciable losses to the Australian chickpea industry. The Northern Grains Region (NGR) of Australia, which accounts for nearly 95% of chickpea production in Australia, is frequently subjected to such events. The objective of this study was to map frost risk in chickpea in the NGR and develop strategies to minimise the impacts of such risk. The Agricultural Production System Simulator (APSIM) modelling framework was used to determine spatial and temporal trends in post-flowering frost risk. The NGR could be divided into six broad sub-regions, each delineating locations with similar frost risk. The risk was nearly two to three times greater in the Southern Downs and Darling Downs sub-regions as compared to the Central Queensland Highlands, Dawson Callide, New South Wales, and Northern New South Wales–Western Downs sub-regions. There was an increasing trend in the frequency of frost events in the Southern Downs and New South Wales sub-regions, and a decreasing trend in the Central Queensland Highlands and Dawson Callide sub-regions, consistent with the changing climate of the NGR. In each sub-region, frost risk declined with delayed sowings, but such sowings resulted in simulation of reduced water limited yield potential (unfrosted) as well. The model output was also used to compute 10, 30, 50, and 70% probabilities of the last day of experiencing −3 to 2 °C minimum temperatures and identify the earliest possible sowings that would avoid such temperatures after flowering. Choosing the earliest sowing times with a 30% frost risk could help increase overall yields in environments with high frost risk. Simulations involving genotype x environment x management interactions suggested additional opportunities to minimise frost losses through the adoption of particular cultivars of differing phenology and the use of different agronomy in various environments of the NGR. The study indicates that there is considerable variation in frost risk across the NGR and that manipulating flowering times either through time of sowing or cultivar choice could assist in minimising yield losses in chickpea due to frost.

In vitro evaluation of tomato (Lycopersicon esculentum Mill.), chilli (Capsicum annum L.), cucumber (Cucumis sativus L.) and Bhendi (Abelmoschus esculentus L.) for salinity stress

Salinity is one of the most important abiotic stresses limiting yield potential. Salinity is even more harmful to seed germination and seedling development. The present study aimed to evaluate the effect of the salinity on germination and seedling growth in four different vegetable crops viz., tomato, chilli, cucumber and bhendi. In this study, germination percentage (%), shoot length (cm), root length (cm), root to shoot ratio, fresh and dry weight (g) were recorded at four different salinity levels (50 mM, 100 mM, 150 mM and 200 mM NaCl) and one control (0 mM NaCl). Significant differences were observed in all the traits in all crops in this study. Based on the germination percentage, by comparing the four crops, cucumber had the highest tolerance to the salinity which was followed by bhendi. The crops of tomato and chilli were more sensitive to salinity.

Preliminary Investigation into the Suitability of Some Selected Soils in Lagos Farming Zones for Tigernut Production, Nigeria

Cultivating crops on land that is not suitable for certain crop will face limited yield potential in spite of the use of improved inputs. However, there is inadequate data on soil nutrients and fertility status of these farming zones in Lagos state for a crop like tigernut. Its production has not been a common state. Therefore, this research focused on assessing the fertility status and suitability for tigernut production of these selected soils from three farming zones of Lagos state of Nigeria. Thirty- six (36) composite soil samples were collected from three farming zones (twelve samples per zone; Badagry, Epe and Ikorodu) and were analyzed for chemical and physical properties. Eighteen soil samples were used for the screen-house experiment to assess the growth and yield of tigernut. All data collected were analyzed using ANOVA (α 0.05 ). The laboratory and screen-house results revealed that the soils were suitable for tigernut production. Nuts yields observed under no fertilizer application treatments were 16.3±0.8, 20.5±2.0 and 13.1±2.2 g and 25.2 ±4.1, 41.4±7.3 and 35.7±3.0 g/pot under fertilizer application for Badagry, Epe and Ikorodu, respectively. Therefore, it is recommended that tigernut should be cultivated in these three farming zones of the state.

Using fertiliser to maintain soil inorganic nitrogen can increase dryland wheat yield with little environmental cost

Nitrogen (N) deficiency is responsible for a large proportion of the exploitable yield gap that exists in Australian wheat production. In order to maximise N use efficiency (NUE), growers attempt to match N fertiliser to seasonal water limited yield potential, which in the southern grain growing region is largely determined by in-crop rainfall. Australia’s variable rainfall makes water limited yield potential very difficult to predict, and growers tend to under fertilise, fearing economic and environmental losses of N if crops are over-fertilised. However, environmental losses of excess N are low in the semi-arid, winter dominant rainfall environments with high water holding capacity soils that comprise much of the wheat producing regions of south eastern Australia. This is particularly the case when high carbon (C) to N ratio crop residues are retained which facilitate rapid immobilisation of any mineral N surplus to crop requirements. We therefore propose that the exploitable yield gap in wheat could be closed if a longer-term strategy of N fertiliser application was adopted. In this strategy, growers would simply use N fertiliser to maintain an environmentally appropriate base level of inorganic N (N bank) rather than attempting to match fertiliser inputs to seasonal conditions. We used field studies with 15N labelled fertiliser and cropping systems simulations to demonstrate that fertiliser N applied at rates calculated to maintain fixed thresholds of inorganic N (N bank criteria) and top-dressed immediately prior to the period of rapid crop uptake can substantially increase yields and profit in comparison to current practice, even when applications exceed crop demand in some years. A further benefit of this strategy is an increase in soil organic matter. Both field and simulation studies indicate that the environmental cost of such a strategy would be minimal, with only a small increase in leaching and denitrification despite higher overall rates of N application. This strategy needs to be compared with current practices in longer term field experiments to confirm production increases and lack of environmental impacts.

Elevated CO2 (free-air CO2 enrichment) increases grain yield of aluminium-resistant but not aluminium-sensitive wheat (Triticum aestivum) grown in an acid soil.

Soil acidity currently limits root growth and crop production in many regions, and climate change is leading to uncertainties regarding future food supply. However, it is unknown how elevated CO2 (eCO2) affects the performance of wheat crops in acid soils under field conditions. We investigated the effects of eCO2 on plant growth and yield of three pairs of near-isogenic hexaploid wheat lines differing in alleles of aluminium-resistant genes TaALMT1 (conferring root malate efflux) and TaMATE1B (conferring citrate efflux). Plants were grown until maturity in an acid soil under ambient CO2 (aCO2; 400 µmol mol-1) and eCO2 (550 µmol mol-1) in a soil free-air CO2 enrichment facility (SoilFACE). Growth parameters and grain yields were measured. Elevated CO2 increased grain yield of lines carrying TaMATE1B by 22 % and lines carrying only TaALMT1 by 31 %, but did not increase the grain yield of Al3+-sensitive lines. Although eCO2 promoted tiller formation, coarse root length and root biomass of lines carrying TaMATE1B, it did not affect ear number, and it therefore limited yield potential. By contrast, eCO2 decreased or did not change these parameters for lines carrying only TaALMT1, and enhanced biomass allocation to grains thereby resulting in increased grain yield. Despite TaMATE1B being less effective than TaALMT1 at conferring Al3+ resistance based on root growth, the gene promoted grain yield to a similar level to TaALMT1 when the plants were grown in acid soil. Furthermore, TaALMT1 and TaMATE1B were not additive in their effects. As atmospheric CO2 increases, it is critical that both Al3+-resistance genes (particularly TaALMT1) should be maintained in hexaploid wheat germplasm in order for yield increases from CO2 fertilization to be realized in acid soils.

Evaluation of elite rice genotypes for physiological and yield attributes under aerobic and irrigated conditions in tarai areas of western Himalayan region

All the irrigated rice systems are currently facing a worldwide challenge for producing higher yield with lower water availability. Aerobic rice is considered to be promising for rice production under water constrained environments where it can be grown under non-flooded and unsaturated soil. All practices for aerobic rice cultivation must start by first identifying promising rice varieties that are expected to produce higher grain yield under such conditions. Therefore, we conducted a field experiment with an experimental design of split-plot in the Tarai region of the Western Himalayas, India, in two irrigation regimes i.e., of continuous flooding and of aerobic condition, using four high-yielding rice genotypes: DRRH-2, PA6444, KRH-2 and Jaya. A grain yield of 743 to 910 g/m2 was obtained on a typical freely draining soil i.e., under aerobic conditions. Further, DRRH-2 showed enhanced panicle number, spikelet number, filled grain number under aerobic conditions, resulting in the higher grain yield of 910 g m/m2. We conclude from our studies that the higher productivity of rice depends upon the improved sink capacity (grain number x grain weight) of the genotype, and that this acts as a major factor limiting yield potential under aerobic and flooded conditions.

Agronomic Performance of Waxy Sorghum Hybrids Derived from US Lines and Korean Landraces

In the past years, few grain sorghum varieties with limited yield potential have been developed and grown in Korea. Hybrids tend to be more productive and resistive to unfavorable environmental conditions than pure line varieties. However, no hybrid cultivars are available and never have been planted for grain sorghum in Korea. The main aims of this study were to (i) verify if US x Korean and US x US hybrids increase grain yield in Korea; (ii) assess the performance of waxy hybrids in Korea and the US; (iii) estimate general combining ability and specific combining ability for the lines studied; and (iv) identify superior lines and hybrids for future use in breeding. Two distinct sets of waxy-endosperm sorghum hybrids derived from Korean landraces and US lines (Texas A&M University) were tested in the US and Korea. Compared to the parental lines, hybrids derived from US lines and Korean landraces showed yield increase that ranged from 2% to 127%. Hybrids created from US lines showed higher heterosis than US x Korean hybrids. Hybrid vigor was observed in the US and Korea, but shifts in ranks of hybrid performance occurred. The results indicate that it is feasible to develop grain sorghum hybrids adapted to Korean conditions only if delibrate selections take place in Korea. A combination of Korean and US sources could provide an acceptable germplasm base for developing Korean landrace based sorghum hybrids.

The carbon footprints of alternative value chains for biomass energy for cooking in Kenya and Tanzania

Due to its availability and affordability for poorer populations, wood-based biomass energy remains vital in meeting local energy demands – especially for cooking fuel – in many regions of the developing world. However, increasing feedstock scarcity (e.g. due to deforestation) coupled with the negative socio-economic and environmental outcomes of inefficient production and consumption technologies make it imperative to identify alternative energy solutions that benefit people without harming the environment. Indeed, tackling energy poverty is crucial to efforts aimed at meeting sustainable development goals at the household level. However, interventions aimed at reducing energy poverty must simultaneously seek solutions that might reduce people’s carbon footprint. Carbon footprints, or the amounts of greenhouse gas emissions linked to particular activities, are associated with climate change and its impacts. Globally, calls have intensified to reduce the carbon footprint of energy use, including use of biomass fuels. Locally, climate change issues are increasingly seen as posing particular threats to already vulnerable communities. The present paper evaluates the carbon footprints of alternative biomass energy solutions for cooking, as one key aspect of their environmental performance. It compares the carbon footprints of firewood, charcoal, biogas, jatropha oil, and crop residue briquettes. The research focuses on selected technologies for biomass energy production and consumption in two case study sites in rural and urban contexts of Kenya and Tanzania. Carbon footprinting is applied as a methodological approach to evaluating technological options for sustainable development in developing economies undergoing rapid population growth, urbanization, and industrial development. Results indicate that the unimproved charcoal value chain has a big carbon footprint. The value chain for jatropha oil appears to hold the greatest potential for carbon footprint reductions, as long as the feedstock is grown in the form of hedges around plots. However, the limited yield potential of hedges calls into question the economic viability of this solution. Results further show that carbon footprinting can help to raise awareness and inform stakeholders and decision-makers about alternative, environmentally more suitable biomass energy value chains. However, any assessment of the overall sustainability of these value chains should also integrate socio-economic aspects and factors influencing adoption.

Soybean yield potential estimated in a central region of RS State, Brazil

Despite soybean global economic relevance, its yield levels vary greatly in time and space. The state of Rio Grande do Sul (RS) has a lower average soybean yield than the Brazilian average, except for its Cen­tral region, where high yields and the extension of cultivated areas have been highlighted. Thanks to tech­nology, high-quality cultivars, and professionalization of farmers, soybean tends to increase yield after every season. However, adverse weather is one of the factors that limit yield potential. The influence of factors that limit yield can be better understood if the crop yield potential is known. Therefore, the aim of this study was to estimate soybean yield potential in the central region of RS, based on mathematical models using historical climate data. According to the observations, it was concluded that the model has the potential to set optimum sowing times based on agronomic aspects, besides allowing for the estima­tion of soybean maximum regional production, showing that there is still much to improve and adapt to obtain high yield in crop management.

Identification of adaptation traits to drought in collections of maize landraces from southern Europe and temperate regions

Breeding maize for drought tolerance is becoming a major challenge in a context of climate changes and restricted irrigation. Gene banks contain underused genetic resources and adaptation traits for drought tolerance may be present in some populations originating from dry regions. We screened, under contrasted water regimes in dry-Mediterranean climate, populations originating from dry cropping zones in Southern Europe, and other populations from temperate regions with a good combining ability for yield and good agronomic features under drought scenarios in a previous study. We evaluated 78 populations for leaf growth, anthesis-silking interval, number of ears per plant, number of kernels per plot, and grain yield in the presence and absence of water stress, in field conditions, over 2 years. Maximum grain yield and the sensitivity of grain yield to water deficit were highly variable. Positive correlations between sensitivity and performance in well-watered conditions were found for yield and number of kernels. Landraces originating from dry regions were generally less sensitive to water stress and had a limited grain yield potential, with variability observed even among accessions from the same survey area. However, some of them had a relatively high yield under stress conditions. During screening for traits associated with the maintenance of grain yield under conditions of water limitation, we identified sources of drought tolerance in breeding populations and landraces from temperate areas as well as in landraces collected in dry regions, indicating large reservoir of native traits in collections for breeding for drought-prone environments.