Significant Yield Decline Research Articles

Transcriptome Analyses Reveal Essential Roles of Alternative Splicing Regulation in Heat-Stressed Holstein Cows.

Heat stress (HS) severely impacts the productivity and welfare of dairy cows. Investigating the biological mechanisms underlying HS response is crucial for developing effective mitigation and breeding strategies. Therefore, we evaluated the changes in milk yield, physiological indicators, blood biochemical parameters, and alternative splicing (AS) patterns of lactating Holstein cows during thermoneutral (TN, N = 19) and heat-stress (HS, N = 17) conditions. There was a significant (p < 0.05) decline in milk yield as physiological indicators increased after exposure to natural HS conditions. The levels of eight out of 13 biochemical parameters of HS were also significantly altered in the presence of HS (p < 0.05). These results demonstrate that HS negatively influences various biological processes of Holstein cows. Furthermore, we investigated AS events based on the RNA-seq data from blood samples. With HS, five common types of AS events were generally increased by 6.7–38.9%. A total of 3470 AS events corresponding to 3143 unique genes were differentially alternatively spliced (DSGs) (p-adjusted < 0.05) between TN and HS groups. The functional annotation results show that the majority of DSGs are involved in mRNA splicing and spliceosomal complex, followed by enrichment in immune and metabolic processes. Eighty-seven out of 645 differentially expressed genes (DEGs) (fold change ≥ 1.5 and false discovery rate < 0.05) overlapped with DSGs. Further analyses showed that 20 of these genes were significantly enriched for the RNA splicing, RNA binding, and RNA transport. Among them, two genes (RBM25 and LUC7L3) had strong interrelation and co-expression pattern with other genes and were identified as candidate genes potentially associated with HS responses in dairy cows. In summary, AS plays a crucial role in changing the transcriptome diversity of heat-stress-related genes in multiple biological pathways and provides a different regulation mechanism from DEGs.

Responses of water balance component to land use/land cover and climate change using geospatial and hydrologic modeling in the Gidabo watershed, Ethiopia

The impact of climate change (CC) and land-use/land-cover (LULC) change on water resources poses a major threat globally. This study investigates the separate and combined responses of CC and LULC change on water balance in Gidabo watershed, Ethiopia, using Soil and Water Assessment Tool (SWAT), Cellular Automata-Markov Chain, and regional climate models. CC projection under RCP 4.5 and hydrological modeling show a significant decline in mean annual surface runoff (Q), baseflow (BF), water yield (WY), percolation (PC), and evapotranspiration (ET) during mid-century (2027–2056) as well as late-century (2061–2090) compared to the baseline period (1988–2018) data, largely due to decline in rainfall. Likewise, under RCP 8.5 scenario, the modeling results show a decrease in Q, BF, WY, PC, and ET during these periods. The LULC change (often associated with an expansion in cultivated and urban areas and a reduction in evergreen forest and grassland) alone leads to a positive synergy with an increase in mean annual Q and WY and a negative synergy with a decrease in BF, PC and ET during the period 2018 to 2075. The combined effects of climate and LULC changes have also shown a decline in Q, BF, WY, PC and ET. Overall, the climate change impacts significantly the future Q and WY. However, the combined effect of climate and LULC changes on BF, PC, and ET is more prominent than their separate impacts and it underlines the significance of this study.

Effects of silicon application on leaf structure and physiological characteristics of Glycyrrhiza uralensis Fisch. and Glycyrrhiza inflata Bat. under salt treatment

BackgroundSoil salinization leads to a significant decline in crop yield and quality, including licorice, an important medicinal cash crop. Studies have proofed that the application of exogenous silicon can significantly improve the ability of licorice to resist salt stress, however, few studies concentrated on the effects of foliar silicon application on the morphology, physiological characteristics, and anatomical structure of licorice leaves under salt stress. In this study, the effects of Si (K2SiO3) on the structural and physiological characteristics of Glycyrrhiza uralensis Fisch. and G. inflata Bat. leaves under different salt concentrations (medium- and high-salt) were studied.ResultsCompared with the control (without salt), the plant height, total dry weight, leaf area, leaf number, relative water content, xylem area, phloem area, ratio of palisade to spongy tissue, gas exchange parameters, and photosynthetic pigment content of both licorice varieties were significantly reduced under high-salt (12S) conditions. However, the thickness of the leaf, palisade tissue, and spongy tissue increased significantly. Applying Si to the leaf surface increased the area of the vascular bundle, xylem, and parenchyma of the leaf’s main vein, promoted water transportation, enhanced the relative leaf water content, and reduced the decomposition of photosynthetic pigments. These changes extended the area of photosynthesis and promoted the production and transportation of organic matter. G. uralensis had a better response to Si application than did G. inflata.ConclusionsIn conclusion, foliar application of Si can improve water absorption, enhance photosynthesis, improve photosynthetic capacity and transpiration efficiency, promote growth and yield, and alleviate the adverse effects of salt stress on the leaf structure of the two kinds of licorice investigated.

Limited acclimation of early life stages of the coral Seriatopora hystrix from mesophotic depth to shallow reefs

Mesophotic coral ecosystems (MCEs, reefs between 30 and 150 m depth) have been hypothesized to contribute to shallow reef recovery through the recruitment of larvae. However, few studies have directly examined this. Here we used mesophotic colonies of Seriatopora hystrix, a depth generalist coral, to investigate the effect of light intensity on larval behavior and settlement through ex situ experiments. We also investigated juvenile survival, growth, and physiological acclimation in situ. Bleached larvae and a significant reduction in settlement rates were found when the mesophotic larvae were exposed to light conditions corresponding to shallow depths (5 and 10 m) ex situ. The in situ experiments showed that mesophotic juveniles survived well at 20 and 40 m, with juveniles in shaded areas surviving longer than three months at 3–5 m during a year of mass bleaching in 2016. Juvenile transplants at 20 m showed a sign of physiological acclimation, which was reflected by a significant decline in maximum quantum yield. These results suggest that light is a significant factor for successful recolonization of depth-generalist corals to shallow reefs. Further, recolonization of shallow reefs may only occur in shaded habitats or potentially through multigenerational recruitments with intermediate depths acting as stepping stones.

Comparative Transcriptome and Metabolome Analysis of Resistant and Susceptible Piper Species Upon Infection by the Oomycete Phytophthora Capsici.

Phytophthora capsici is a destructive oomycete pathogen that causes devastating disease in black pepper, resulting in a significant decline in yield and economic losses. Piper nigrum (black pepper) is documented as susceptible to P. capsici, whereas its close relative Piper flaviflorum is known to be resistant. However, the molecular mechanism underlying the resistance of P. flaviflorum remains obscure. In this study, we conducted a comparative transcriptome and metabolome analysis between P. flaviflorum and P. nigrum upon P. capsici infection and found substantial differences in their gene expression profiles, with altered genes being significantly enriched in terms relating to plant-pathogen interaction, phytohormone signal transduction, and secondary metabolic pathways, including phenylpropanoid biosynthesis. Further metabolome analysis revealed the resistant P. flaviflorum to have a high background endogenous ABA reservoir and time-course-dependent accumulation of ABA and SA upon P. capsici inoculation, while the susceptible P. nigrum had a high background endogenous IAA reservoir and time-course-dependent accumulation of JA-Ile, the active form of JA. Investigation of the phenylpropanoid biosynthesis metabolome further indicated the resistant P. flaviflorum to have more accumulation of lignin precursors than the susceptible P. nigrum, resulting in a higher accumulation after inoculation. This study provides an overall characterization of biologically important pathways underlying the resistance of P. flaviflorum, which theoretically explains the advantage of using this species as rootstock for the management of oomycete pathogen in black pepper production.

Metabolome and transcriptome analyses of plants grown in naturally attenuated soil after hydrogen fluoride exposure

Accidental chemical leaks and illegal chemical discharges are a global environmental issue. In 2012, a hydrogen fluoride leak in Gumi, South Korea, killed several people and contaminated the environment. This leak also led to a significant decline in crop yield, even after the soil concentration of hydrogen fluoride decreased to below the standard level following natural attenuation. To determine the cause of this decreased plant productivity, we designed direct and indirect exposure tests by evaluating the metabolome, transcriptome, and phenome of the plants. In an indirect exposure test, soil metabolomics revealed downregulation of metabolites in vitamin B6, lipopolysaccharide, osmolyte, and exopolysaccharide metabolism. Next-generation sequencing of the plants showed that ABR1 and DREB1A were overexpressed in response to stress. Plant metabolomics demonstrated upregulation of folate biosynthesis and nicotinate and nicotinamide metabolism associated with detoxification of reactive oxygen species. These results demonstrate impaired metabolism of soil microbes and plants even after natural attenuation of hydrogen fluoride in soil. The novel chemical exposure testing used in this study can be applied to identify hidden damage to organisms after natural attenuation of chemicals in soil, as well as biomarkers for explaining the decline in yield of plants grown in soil near pollutant-emitting industrial facilities.

Circulating cell-free DNA undergoes significant decline in yield after prolonged storage time in both plasma and purified form.

Circulating DNA (cirDNA) is generally purified from plasma that has been biobanked for variable lengths of time. In long-term experiments or clinical trials, the plasma can be stored frozen for up to several years. Therefore, it is crucial to determine the stability of cirDNA to ensure confidence in sample quality upon analysis. Our main objective was to determine the effect of storage for up to 2years on cirDNA yield and fragmentation. We stored frozen EDTA plasma and purified cirDNA from 10 healthy female donors, then quantified cirDNA yield at baseline, and at regular intervals for up to 2years, by qPCR and Qubit. We also compared cirDNA levels in non-haemolysed and haemolysed blood samples after 16months of storage and tested the effect of varying DNA extraction protocol parameters. Storage up to two years caused an annual cirDNA yield decline of 25.5% when stored as plasma and 23% when stored as purified DNA, with short fragments lost more rapidly than long fragments. Additionally, cirDNA yield was impacted by plasma input and cirDNA elution volumes, but not by haemolysis. The design of long-term cirDNA-based studies and clinical trials should factor in the deterioration of cirDNA during storage.

Sensitivity of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) to excessive copper foliar spray concentration when grown in a calcareous soil

Copper (Cu) foliar spray is a requested technique to prevent Cu deficiency in cereals grown in calcareous soil. The reasonable Cu foliar feeding requires identifying the Cu phytotoxic threshold. Such a threshold will help producers to prevent the negative impact of excessive foliar Cu application. The aim was to compare the phytotoxic effect of foliar Cu spray on wheat and barley. The field experiments were conducted in calcareous soil (16.5% of free carbonates) that contains 0.26 mg kg−1 of Cu (DTPA-Extraction). Six Cu foliar spray concentrations were tested in wheat (0% or control; 0.2%; 0.4%; 0.6%; 0.8% and 1%) and barley (control; 0.2%; 0.4%; 0.6%; 1% and 2%) using a randomized complete blocks with five replications. Leaf Cu was supplied at the stem extension and booting stages using the sulfate form (CuSO4.5H2O). Cu foliar spray of 0.2% resulted in leaf damage for wheat. Barley did not show phytotoxic symptoms even at 2% of Cu. A significant decline in wheat grain yield (-20%) was recorded at Cu foliar spray of 1% compared to control. For barley, a grain yield decline (-14%) was induced at 2% Cu foliar spray compared to the optimum yielding recorded at 0.94% of Cu. The Cu flag leaf content reached 130 and 13 mg.kg−1, respectively, for wheat and barley at 1% of sprayed Cu. The flag leaf contents on other nutrients were invariable. The current study demonstrates that the negative impact of Cu phytotoxicity was more pronounced in wheat compared to barley at excessive Cu concentration of foliar feeding.

Integrated Analysis of Physiological, mRNA Sequencing, and miRNA Sequencing Data Reveals a Specific Mechanism for the Response to Continuous Cropping Obstacles in Pogostemon cablin Roots.

Pogostemon cablin (patchouli) is a commercially important medicinal and industrial crop grown worldwide for its medicinal and aromatic properties. Patchoulol and pogostone, derived from the essential oil of patchouli, are considered valuable components in the cosmetic and pharmaceutical industries. Due to its high application value in the clinic and industry, the demand for patchouli is constantly growing. Unfortunately, patchouli cultivation has suffered due to severe continuous cropping obstacles, resulting in a significant decline in yield and quality. Moreover, the physiological and transcriptional changes in patchouli in response to continuous cropping obstacles remain unclear. This has greatly restricted the development of the patchouli industry. To explore the mechanism underlying the rapid response of patchouli roots to continuous cropping stress, integrated analysis of the transcriptome and miRNA profiles of patchouli roots under continuous and noncontinuous cropping conditions in different growth periods was conducted using RNA sequencing (RNA-seq) and miRNA-seq and complemented with physiological data. The physiological and biochemical results showed that continuous cropping significantly inhibited root growth, decreased root activity, and increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the levels of osmoregulators (malondialdehyde, soluble protein, soluble sugar, and proline). Subsequently, we found 4,238, 3,494, and 7,290 upregulated and 4,176, 3,202, and 8,599 downregulated differentially expressed genes (DEGs) in the three growth periods of continuously cropped patchouli, many of which were associated with primary carbon and nitrogen metabolism, defense responses, secondary metabolite biosynthesis, and transcription factors. Based on miRNA-seq, 927 known miRNAs and 130 novel miRNAs were identified, among which 67 differentially expressed miRNAs (DEMIs) belonging to 24 miRNA families were induced or repressed by continuous cropping. By combining transcriptome and miRNA profiling, we obtained 47 miRNA-target gene pairs, consisting of 18 DEMIs and 43 DEGs, that likely play important roles in the continuous cropping response of patchouli. The information provided in this study will contribute to clarifying the intricate mechanism underlying the patchouli response to continuous cropping obstacles. In addition, the candidate miRNAs and genes can provide a new strategy for breeding continuous cropping-tolerant patchouli.

Differential response of physiology and metabolic response to drought stress in different sweetpotato cultivars.

Sweetpotato (Ipomoea batatas [L.] Lam) is a widely cultivated food crop with generally good adaptability. However, drought stress can cause a significant decline in yield. To reveal the response mechanism of sweetpotato to drought stress, an integrated physiological, proteomic and metabolomic investigation was conducted in leaves of two sweetpotato varieties with differing responses to drought stress, drought-resistant Wanzishu56 (WZ56) and a more sensitive variety, Ningzishu2(NZ2). Physiological analysis showed that the variety with better drought tolerance had superior performance in water retention capacity and photosynthetic efficiency under drought stress. A total of 1140 proteins were identified within the two varieties. Among them, 192 differentially expressed proteins were detected under drought conditions, including 97 that were up-regulated. Functional analysis showed that these up-regulated proteins were primarily involved in photosynthesis, reactive oxygen species metabolism, organonitrogen compound metabolism, and precursor metabolite catabolism and energy generation. All differentially expressed proteins in WZ56 that were involved in photosynthetic and glutathione metabolic processes were up-regulated. Enzyme activity assays were carried out to validate the proteomics data. Moreover, 75 metabolites were found to have a higher expression level in WZ56 than NZ2 under drought stress. The higher concentration of carbohydrates, amino acids, flavonoids and organic acids found in drought-stressed leaves of WZ56 suggested that these metabolites may improve the drought resistance of sweetpotato. This study uncovered specific-proteins and metabolites associated with drought resistance, providing new insights into the molecular mechanisms of drought tolerance in sweetpotato.

Harvest Time Can Affect the Optimal Yield and Quality of Sea Lettuce (Ulva fenestrata) in a Sustainable Sea-Based Cultivation

Seaweed biomass is a renewable resource with multiple applications. Sea-based cultivation of seaweeds can provide high biomass yields, low construction, operation, and maintenance costs and could offer an environmentally and economically sustainable alternative to land-based cultivations. The biochemical profile of sea-grown biomass depends on seasonal variation in environmental factors, and the optimization of harvest time is important for the quality of the produced biomass. To identify optimal harvest times of Swedish sea-based cultivated sea lettuce (Ulva fenestrata), this study monitored biomass yield, morphology, chemical composition, fertility, and biofouling at five different harvesting times in April – June 2020. The highest biomass yields (approximately 1.2 kg fw [m rope]–1) were observed in late spring (May). The number and size of holes in the thalli and the amount of fertile and fouled tissue increased with prolonged growth season, which together led to a significant decline in both biomass yield and quality during summer (June). Early spring (April) conditions were optimal for obtaining high fatty acid, protein, biochar, phenolic, and pigment contents in the biomass, whereas carbohydrate and ash content, as well as essential and non-essential elements, increased later in the growth season. Our study results show that the optimal harvest time of sea-based cultivatedU. fenestratadepends on the downstream application of the biomass and must be carefully selected to balance yield, quality, and desired biochemical contents to maximize the output of future sea-based algal cultivations in the European Northern Hemisphere.

Climate Variability Masked Greening Effects on Water Yield in the Yangtze River Basin During 2001–2018

AbstractRapid global vegetation greening has been observed for the past two decades, but its implications to the hydrological cycle are not well understood in many regions, including the Yangtze River Basin (YRB). This study used a remote sensing‐driven ecosystem model, the Coupled Carbon and Water model, to fully examine the individual and combined hydrological effects of vegetation and climate changes through a series of modeling experiments. During the study period (2001–2018), the vegetation showed a significant greening trend with the mean annual normalized difference vegetation index increasing at a rate of 0.4% per year (p &lt; 0.001). In contrast, climate exhibited a marginal wetting trend with annual precipitation increasing at a rate of 6.7 mm/yr (p = 0.08). Annual evapotranspiration (ET) in the YRB significantly increased (3.1 mm/yr, p = 0.01) primarily due to enhanced ecosystem productivity associated with vegetation greening, rather than climatic factors. However, the enhancement in ET did not lead to a significant decline in total water yield at the YRB scale. The large inter‐annual variability of precipitation masked the effects of vegetation greening on water yield. Overall, our study indicated that the recent land “greening up” has accelerated the regional hydrological cycle through increasing ET and resulted in enhanced risks of water resource shortage. Our findings highlighted the close connection between land cover dynamics and hydrological cycle under climate variability in one of the world’s largest river systems. Effective basin water resource management must consider hydrological response to vegetation greening and climate change.

Effects of Continuous Cropping of Codonopsis tangshen on Rhizospheric Soil Bacterial Community as Determined by Pyrosequencing

Codonopsis tangshen, a perennial herbaceous, has been shown to be affected by continuous cropping, with significant decline in both yield and quality. In this study, we studied the effect of continuous cropping on the abundance and composition of rhizospheric soil bacterial community. Results showed that continuous cropping causes a significant decline in both yield and quality. The nutrient content in continuous cropping soil was higher than that of soil in main cropping. Pyrosequencing analyses revealed Proteobacteria and Acidobacteria as the main phyla in two types of soils. Relative abundance of Acidobacteria, Nitrospirae, TM7, and AD3 phyla was observed to be high in continuous cropping soils, whereas Chloroflexi, Bacteroidetes, and Planctomycetes phyla were richer in main cropping soils. At the genus level, high relative abundance of Pseudomonas (γ-Proteobacteria), Rhodanobacter, Candidatus Koribacter, and Candidatus were observed in continuous cropping soil. Different patterns of bacterial community structure were observed between different soils. Redundancy analysis indicated that organic matter content and available nitrogen content exhibited the strongest effect on bacterial community structure in the continuous cropping soil. Taken together, continuous cropping led to a significant decline in yield and quality, decrease in rhizospheric soil bacterial abundance, and alteration of rhizospheric soil microbial community structure, thereby resulting in poor growth of C. tangshen in the continuous cropping system.

Mixing of biochar, vinegar and mushroom residues regulates soil microbial community and increases cucumber yield under continuous cropping regime

Continuous cropping is a common practice in protected agriculture, although it results in a significant decline in soil quality and crop yield. Considering the large yearly production of vinegar and mushroom residues in China, the current study aimed to investigate the effects of different organic residue amendments on soil quality in the protected cultivation of cucumber under continuous cropping regime. Accordingly, a pot experiment was conducted with the following treatments: soil without amendment (CK), soil amendment with commercial conditioner (C), biochar (B), vinegar (V) and mushroom (M) residue (VM, V:M, 3:1), and the mixtures of vinegar, mushroom residue, and biochar (VMB, V:M:B, 3:1:4). The results showed that the soil pH, soil water content (SWC), and organic carbon (OC) content significantly increased after soil amendments. Vinegar and mushroom residues improved the content of soil N, P, and K. In contrast, biochar substantially decreased the total phenol content and electrical conductivity. Moreover, microbial diversity significantly increased with VMB amendment, and structural equation modeling (SEM) indicated that the microbial Chao1 index was strongly linked to cucumber yield. Furthermore, the yield of cucumber had a strong correlation with microbial diversity compared with soil physico-chemical properties. Chloroflexi, Actinobacteria and Gemmatimonadetes were significantly enriched by different amendments. Our results suggest that soil amendments can directly regulate the soil microbial community or induce compositional shifts of microbes by changing soil physico-chemical characteristics under continuous cropping regime. The coamendment of soil with vinegar and mushroom residues plus biochar is an effective method to reduce the negative effects of continuous cropping in protected cultivation. The study provides convincing evidence that the application of organic amendments and management of residues are potential sustainable strategies to increase agricultural productivity in protected horticulture.

Growth, Yield and Quality of Maize under Ozone and Carbon Dioxide Interaction in North West India

ABSTRACT Maize is an important C4 crop and how it will respond to elevated atmospheric carbon dioxide and ozone levels is not well documented. To understand how the growth and nutritional quality of maize will be affected under elevated carbon dioxide (CO2) and tropospheric ozone (O3) interaction, a field experiment was conducted under free air O3 and CO2 enrichment rings (FAOCE) growing HQPM-1 and PMH-1 maize cultivars at New Delhi, India. Each cultivar was exposed to ambient and elevated CO2 (559 ppm) alone and along with ambient and elevated O3 (71.8 ppb) throughout the growing period. Elevated CO2 (EC) significantly increased the leaf area index (10.8–22.5%), chlorophyll (11.2–17.3%) and photosynthetic rate (12.1–16.5%) in the two cultivars over the ambient. O3 exposure of 27 ppm hr (AOT4O) under elevated O3 (EO) treatment led to a significant decline in yield (p < 0.01) by 9.2% in HQPM-1 and 9.8% in PMH-1. Under elevated CO2 the increase in grain yield was higher under HQPM-1 (25.4%) as compared to PMH-1 (9.04%). The protein content increased under EO (8.1–12.5%) and decreased under EC (13.4–13.6%) in the two maize cultivars due to yield dilution effect. Lysine, phosphorus and potassium content of the grain significantly decreased in both the cultivars under elevated CO2. Carbohydrate and amylose concentrations in grains increased (9.9–15.5%) under EC and decreased (10.8–16.7%) under EO, however, no significant change in yield, protein, amylase, carbohydrate, lysine, potassium and phosphorus was observed under the interaction treatment ECO as compared to the ambient. After two years of study we could conclude that elevated CO2 (559 ppm) was able to offset the negative effect of elevated O3 (71 ppb) on grain yield by 11.2% in PMH-1 and by 18.8% in HQPM-1 without significantly affecting the grain quality in both the maize cultivars.

Effect of deficit irrigation on physiology, plant growth, and fruit yield of cucumber cultivars

Increased water scarcity necessitates the implementation of water-conserving irrigation management practices to sustain crop production,especially in water-limited areas. A two-year field study was conducted during 2019 and 2020 to evaluate the effect of deficit irrigation on physiology, plant growth, and yield of cucumber cultivars. The experiment was conducted in a split-plot design with four irrigation levels (100% ETc (crop evapotranspiration), 80% ETc, 60% ETc, and 40% ETc) as main plot factor and two cultivars (Poinsett 76 and Marketmore 76) as subplot factor with three replications. Results showed that stomatal conductance (gs), transpiration rate (E), photosynthesis rate (Pn), intercellular CO2 concentration (Ci), and leaf area were significantly lower in 60% ETc and 40% ETc compared to 100% ETc while stomatal limitations, intrinsic water use efficiency (WUEi), and relative leaf temperature were significantly higher in 60% ETc and 40% ETc compared to 100% ETc. The observed values of these aforementioned parameters were comparable between 100% ETc and 80% ETc. A decrease in leaf area, as well as a decrease in Pn, resulted in a decline in overall photosynthesis per plant in 60% ETc and 40% ETc compared to 100% ETc. As a consequence of this, plant dry biomass and total fruit yield were significantly lower in 60% ETc and 40% ETc compared to 100% ETc. However, photosynthesis per plant was comparable between 100% ETc and 80% ETc due to comparable Pn and leaf area between them. Because of comparable photosynthesis per plant, plant dry biomass and fruit yield were comparable between 100% ETc and 80% ETc. Marketmore 76 had significantly higher gs, E, Pn, Ci, and leaf area and it had significantly lower stomatal limitations, WUEi, and relative leaf temperature than Poinsett 76. Vegetative dry biomass and total above-ground dry biomass were higher in Marketmore 76 but fruit yield was higher in Poinsett 76. These results suggest that 80% ETc irrigation level and Poinsett 76 cultivar can be recommended for successful cucumber production without causing a significant decline in fruit yield in water-limited Southern High Plains of United States.

Selection of high-yielding pea varieties in the conditions of the Cis-Ural steppe zone of the Bashkortostan Republic

Peas have become the most important leguminous crop worldwide. Large areas in Russia are used for pea growing. Unfavourable weather and climatic conditions often lead to a significant yield decline. There is an urgent need to develop new high-yielding varieties adapted to local conditions. The current paper presents the results of long-term breeding of modern pea cultivars Chishminsky 229, Pamiati Hangildina, Pamiati Popova, meeting the requirements of agricultural production. The research was conducted in the Bashkir Agricultural Research Institute. The varieties were bred by repeated single selection based on intervariety hybridization. Chishminsky 229 and Pamiati Hangildina cultivars are included in the State Register of Breeding Achievements. Pamiati Popova is currently undergoing state variety testing. According to the comparative testing in 2016-2020, the excess yield compared to Chishminsky 95 standard variety was 2.1 c/ha for Chishminsky 229 variety, 1.9 c/ha for Pamiati Hangildina cultivar, and 3.2 c/ha for Pamiati Popova cultivar.

On the use of mean and extreme climate indices to predict sugar yield in western Fiji

Sugarcane is one of Fiji's largest commercial agricultural crops and greater than 80% of the raw sugar produced is exported. Few sugar-producing countries are as dependant on the contribution of sugar to the export market as Fiji. There has been a statistically significant decline in sugar yield since 1975. The proportion of sugar extracted from sugarcane has also declined as shown by the positive trend in the tonnes cane to tonnes sugar ratio (+0.07/year, p < 0.001). The role of climate in these changes was investigated by first using principal component analysis then stepwise regression to predict sugarcane and sugar yield. ‘Mild drought conditions’, an increase in the diurnal temperature range and cool conditions during the ripening and maturation period are favourable for sugar yield. The impact of future warmer, wetter and drier conditions on sugar yield was also examined, in the absence of adaptive measures. Results show declines in sugar yield with an increase in mean and extreme temperature. Results also show an increase in the number of rain days in March offsets the increase in temperature suggesting that an increase the number of rain days in the late growing season in a future climate may counter the influence of higher temperatures. As for Australia and other developed sugar producing countries, irrigation in the late growing season may be an option to increase yields and/or adapt to a warmer climate.

Mars Regolith Simulant Ameliorated by Compost as in situ Cultivation Substrate Improves Lettuce Growth and Nutritional Aspects.

Heavy payloads in future shuttle journeys to Mars present limiting factors, making self-sustenance essential for future colonies. Therefore, in situ resources utilization (ISRU) is the path to successful and feasible space voyages. This research frames the concept of planting leafy vegetables on Mars regolith simulant, ameliorating this substrate’s fertility by the addition of organic residues produced in situ. For this purpose, two butterhead lettuce (Lactuca sativa L. var. capitata) cultivars (green and red Salanova®) were chosen to be cultivated in four different mixtures of MMS-1 Mojave Mars simulant:compost (0:100, 30:70, 70:30 and 100:0; v:v) in a phytotron open gas exchange growth chamber. The impact of compost rate on both crop performance and the nutritive value of green- and red-pigmented cultivars was assessed. The 30:70 mixture proved to be optimal in terms of crop performance, photosynthetic activity, intrinsic water use efficiency and quality traits of lettuce. In particular, red Salanova® showed the best performance in terms of these quality traits, registering 32% more phenolic content in comparison to 100% simulant. Nonetheless, the 70:30 mixture represents a more realistic scenario when taking into consideration the sustainable use of compost as a limited resource in space farming, while still accepting a slight significant decline in yield and quality in comparison to the 30:70 mixture.

Optimizing sowing time for boosting productivity and nutritional quality of amaranth (Amaranthus cruentus L.) genotypes under Mediterranean climate

Currently, there is increasing interest in the cultivation of alternative grain crops, such as amaranth (Amaranthus cruentus L.) in Italy. However, few information exist for the most optimal sowing date (SD) of amaranth especially under rainfed conditions. A field-trial was conducted in Tuscany during 2018 to evaluate SD effects on amaranth genotypes (‘Kharkov’ and two new breeding lines coded ‘A-61’ and ‘A67’). The three SD were March 27 (first), April 20 (second), June 4 (third). Only the first and second SD coincided with increasing photoperiod. Cumulative Growing Degree Days (GDD) for ripening were 2282, 1990 and 1480 for the first, second and third SD, respectively. Compared to the first two SD, ground-cover was 20 % less from panicle formation in the third SD, therefore potentially less competitive towards weeds. A-67 was more “palatable” to the incidence of sugar beet flea beetle (Chaenoctema tibialis Illinger) from the earliest stages of growth. In contrast, ‘Kharkov’, was significantly less attacked by the insect over all three SD.‘Kharkov’, demonstrated greater flexibility with stable yields of 1.3 t ha-1 for the first and second SD. In contrast, significant yield reductions (1.5 to 1.2 t ha-1, from the first to second SD, respectively) were evident for both lines of amaranth in response to SD delay. Adverse effects of the third SD, included significant decline in yield, protein content and 1000 seed mass. In conclusion, amaranth, March-April SD may be recommended for obtaining optimal grain yield of amaranth along with making it successful as a viable alternative grain crop under under agro-ecological conditions of Central Italy.