Total Shoot Research Articles

Water and radiation use efficiencies in maize: Breeding effects on single-cross Argentine hybrids released between 1980 and 2012

Water deficit has been signaled as an important determinant of grain yield (GY) gaps between potential and actual GYs. Breeding for improved water as well as solar radiation productivities is a sustainable means to reduce this gap. The aim of this study was to evaluate breeding effects on GY and its physiological determinants, including water (WUE) and radiation (RUE) use efficiencies, of temperate maize hybrids grown under a wide range of environmental conditions in Argentina. We hypothesized that breeding focused on GY performance and broad adaptation produced an increase in crop biomass linked to an increased tolerance to adverse growing conditions, a trend associated with an increase in WUE and/or RUE. For this purpose, hybrids were grown under three stand densities and eight environmental conditions in the main target environment for the production of temperate hybrids in Argentina. Analyzed traits were GY, total shoot biomass (BT) production, harvest index (HI = GY/BT), crop evapotranspiration (ETC), crop radiation interception (IPARC: cumulative amount of intercepted incident photosynthetically active radiation), radiation use efficiency (RUE = BT/IPARC), water use efficiency (WUE) for biomass production (WUEB,ETc= BT/ETC) and WUE for GY production (WUEGY,ETc= GY/ETC). No breeding effect was registered on ETC and IPARC, whereas significant breeding effects (P < 0.05) were detected on GY (0.5 % YOR−1 from 1980 onwards). The latter were due to the improvement of BT (from 1993 onwards) as well as of HI (between 1980 and 1993), with gains of 0.5 % YOR−1 in both cases. Mentioned trends were associated with a significant increase in RUE (0.7 % YOR−1 from 1993 onwards) and consequently in WUEB,ETc (0.6 % YOR−1 from 1993 onwards) and WUEGY,ETc (0.5 % YOR−1 from 1980 onwards). Results demonstrated that breeding efforts, which have been driven almost exclusively by GY improvement, had no evident effect on the crop water use but had clear effects on crop biomass production and its partitioning. These unintended positive effects of breeding on RUE and WUEs are welcome on a global scale, considering that predicted trends of increasing human demand for water will require increased water productivity rather than increased water use by crops.

Growth performance and emergence of invasive alien Rumex confertus in different soil types

Rumex confertus is known to be one of the most serious invasive weed species infesting meadows, pastures and ruderal lands throughout the Central Europe. Rumex confertus was grown in pot experiments using 8 soil types at 5 concentrations of nitrogen (N) and phosphorus (P). Based on harvest data, the variables, seedlings emergence, root: shoot (R: S) ratio, N and P concentration, chlorophyll content, Relative Colimitation Index (RCI) and dry matter allocation to plant components, were determined. N and P addition stimulated the growth of plants in different soils, as reflected by a significant increase in seedling growth parameters such as total plant biomass and shoot biomass. Across all soil types, emergence of seedlings was negatively affected by very high N, but positively affected by increased P availability. This study indicates that Dystric Arenosol, Entic Podzol, Brunic Arenosol and Calcaric Leptosol are unfavorable for R. confertus growth, excluding R. confertus completely. Moreover, evidence suggests that plant growth is limited by both N and P, therefore R. confertus could be controlled by reducing available N and P content in the soil.

Glyphosate residues in soil affect crop plant germination and growth

Glyphosate-based herbicides (GBH) are the most widely used pesticides globally. Their persistence in soils and effects on non-target organisms have become a concern in agricultural and natural ecosystems. We experimentally studied, whether residues of GBH (Roundup Gold) or pure glyphosate in soils affect the germination or sprouting and growth of crop plants after the safety period. The seed germination of faba bean, oat and turnip rape, and sprouting of potato tubers was delayed in the greenhouse experiments in soils treated with GBH or with pure glyphosate. The total shoot biomass of faba bean was 28%, oat 29% and turnip rape 58% higher in control compared to GBH soils four weeks after sowing. In the beginning of the growing season, the plant growth in the field experiment supported the observations in the greenhouse experiment. However, at the end of the field experiment, potato shoot biomass was 25% and tuber biomass 14% greater in GBH soil compared to control soil. Potato tubers tended to gather low amounts of glyphosate (0.02 mg/kg) and its metabolite AMPA (0.07 mg/kg). Grazing by barnacle geese was three times higher in oats growing in the GBH soils compared to control oats in the field. Our results draw attention to complex indirect effects of GBH on crop plant seedling establishment and resistance to herbivores.

Bio-chemical properties and susceptibility to fire blight (Erwinia amylovora Burrill) of scab-resistant apple cultivars (Malus domestica Borkh.)

Abstract The focus of our research was to evaluate different apples cultivars in terms of their biological properties and bioactive compounds content, and determine the levels of their resistance (or susceptibility) to fire blight. The properties of 10 scab-resistant apple cultivars were examined on the Žiča monastery estate (West Serbia) during the period from 2011 to 2015. The biological and chemical properties such as firmness, maturity stage, total soluble solids, total acids, total and reducing sugars, ascorbic acid content and surface blush of apple fruits were monitored. Various phenolic compounds in the tested samples were tentatively identified by LC-MS analyses. A study of generative properties included: number of flower buds, fruit mass and width, crop load, yield efficiency and yield. During the period of blooming and intensive shoot growth, artificial inoculations were carried out. For each cultivar, a fire blight score was determined by dividing the average length of necrotic tissue by the average total shoot length. In the study period, the cultivars ‘GoldRush’ (41.1 t ha−1) and ‘Florina’ (35.9 t ha−1) produced the highest yields, and the cultivars ‘Discovery’ (19.0 t ha−1) and Selection 25/63 (15.1 t ha−1) the lowest. The cultivar ‘William’s Pride’ produced the largest fruits, with an average fruit mass of 206.8 g. The earliest harvest period was recorded for the cultivar ‘Discovery’ (end of July), and the latest for the cultivar ‘GoldRush’ (beginning of October). The cultivar ‘Enterprise’ had the highest value of total phenols (432.2 mg 100 g −1 FW), while the cultivar ‘Topaz’ had the highest value of total flavanols (145.2 mg 100 g−1 FW). The highest degree of susceptibility to fire blight was found in Selection 25/63, and the greatest resistance was manifested by the cultivar ‘GoldRush’. In the five-year study period, the cultivars ‘GoldRush’, ‘Rewena’ and ‘Enterprise’ exhibited better bio-chemical properties and higher levels of resistance to fire blight than the remaining cultivars.

Cut-stem treatments using graminicides for burmareed (Neyraudia reynaudiana) invasions in Pine Rocklands, South Florida, USA

AbstractBurmareed [Neyraudia reynaudiana (Kunth) Keng ex Hitchc.] is an aggressive invader of pine rockland communities in south Florida. Currently, it is managed by clipping the stems and later returning, when plants have regrown to approximately 50 cm in height, to administer applications of glyphosate to new foliar growth (a “cut–return–treat,” or CRT, strategy). This multi-visit strategy is time-consuming and may result in off-target effects due to the broad-spectrum nature of glyphosate. With this study we evaluated a cut-stem (CS) approach, in which stems are cut and immediately treated with herbicide. Further, we tested the efficacy of the selective graminicides sethoxydim and fluazifop-P-butyl. In a pot study, CS treatments included: glyphosate (239.7 g ae L−1) in water, sethoxydim (9.0 g ai L−1) or fluazifop-P-butyl (12.1 g ai L−1) in either basal oil or water, and triclopyr (47.9 g ae L−1) in basal oil. All CS treatments provided mortality and growth reduction comparable to the best CRT treatments (glyphosate, sethoxydim, and fluazifop-P-butyl) and were therefore evaluated under field conditions using the same application rates. Mortality was low in the field (≤30%) regardless of herbicide treatment. Overall, fluazifop-P-butyl provided greater control than sethoxydim, resulting in 71% and 94% relative growth reduction in total shoot length with oil and water carriers, respectively, compared with 50% and 43% reduction for sethoxydim. Fluazifop also provided control similar to triclopyr and glyphosate (≥65% reduction in total shoot length). Results suggest that CS treatments may be a viable strategy for managing N. reynaudiana and reducing management costs. However, more research is needed to optimize rates. Further, fluazifop-P-butyl allows for a more selective option than glyphosate that may decrease off-target effects on native understory vegetation in pine rocklands.

Control of branched broomrape (Orobanche ramosa L.) in tomato (Lycopersicon esculentum Mill.) by olive cake and olive mill waste water

Effects of olive cake and olive mill waste water on Orobanche ramosa L. infection to tomato (Lycopersicon esculentum Mill.) were investigated in pot experiments conducted under glasshouse conditions during the spring/summer seasons of the 2016 and 2017. Treatments included the use of olive mill cake, cake extracts or mill waste water. In all experiments, treatments were arranged in a randomized complete block design with four replicates. Soil mulching with olive cake slightly affected total parasite shoot number but reduced its shoot dry weight compared with infested-control. Tomato shoot dry weight in all mulch treatments was not significantly different from that of parasite-infested control but greatly reduced compared with Orobanche-free control. Weekly application of olive cake aqueous extract for 3–6 weeks after tomato transplanting reduced tomato shoots dry weight and shoots number and dry weight of O. ramosa. Other extract treatments stimulated or had no effect on tomato growth or Orobanche infection compared with Orobanche-infested control. Soil-incorporated olive cake reduced tomato shoot and root dry weights at the highest (300 and 400 g per pot) rates used in the summer but rates between 50 and 400 g/pot significantly reduced tomato growth during the spring. All treatments significantly reduced Orobanche shoot number (except the lowest rate) and dry weight compared with Orobanche-infested control. Pre- or post-plant application of olive mill waste water and up to 400ml/pot showed no phytotoxicity on tomato; but lower rates in post-plant application increased crop shoot and root dry weights over parasite-free control. Total shoot number and dry weight of O. ramosa at 400 ml per pot were reduced by 70% and 74% for both parameters, respectively. In conclusion, olive mill waste water was more selective and effective against O. ramosa than olive cake and of a high potential use for parasite control in tomato.

Developing a fast and accurate model to estimate allometrically the total shoot leaf area in grapevines

Ten different allometric models for estimating leaf area of the primary shoots, lateral shoots and total shoot leaf area of grapevines were developed using data collected from nine different Vitis vinifera L. cultivars. Firstly, the leaf area of main or lateral shoots was estimated according to two allometric models (Lopes and Pinto; Spann and Hereema) already in use for grapevines and other fruit tree species, and three other models appositely developed in this work and obtained after slight modifications of the previous ones. Secondly, five new allometric models were hereby developed to estimate directly total leaf area of the entire vine shoot (main shoot plus laterals). Rigorous statistical analysis enabled the evaluation of the models’ performance in relation to (a) the type and number of predictors used, and (b) the shoot category of interest (i.e. leaf area of main, laterals and total leaf area of the vine shoot). This allowed selecting, in each analysis, the allometric model with the best performance. Although the suitability of previously developed allometric models for estimating the leaf area of single shoots (main or laterals) was confirmed, the current research showed that these models can be improved using power functions (r2 improved from 0.85 to 0.88 and from 0.97 to 0.98 for main and lateral shoots, respectively). However, using these models to estimate the leaf area of an entire shoot requires separate estimation of the main shoot leaf area, that of each of its laterals and then the sum all these estimates. Considering that the number of laterals on each main shoot can be high, this can be very time-consuming. In this study, we developed, for the first time, models that can predict accurately (r2 range 0.95-0.98) and directly the leaf area of the entire shoot (main plus its laterals) using a limited number (3–5) of predictors.

Effect of disturbance on population structure, regeneration and conservation of Moghania chappar in sal forests of Gorakhpur, India

Non-seed regeneration is essentially a vagrant strategy of woody plants causing assemblage of homozygous populations in disturbed forests. We tried to understand how such hardy species like Moghania chappar produce close groups of individuals at different level of disturbance. The hypothesis of trade-off between ramet proliferation and disturbance level, and between growth pattern and resource conservation was tested. The three 1-ha sample plots of sal forest, facing low, moderate or high level of disturbance were observed within Sohagibarwa Wildlife Sanctuary. A total of 40 quadrats per 1-ha plot were sampled to record the age structure of genet and ramet populations of M. chappar. The architecture and foraging of the root-stock was mapped, the biomass of root and shoot was measured and the soil conserved by the root-complex was estimated at each disturbance level. The growth characteristics suggest that M. chappar conforms to Stone’s model of tree architecture. At moderate disturbance, the root-shoot junction sent many more sprouts, garnered much biomass and became flat and curved. The insurrection of ramets caused fragmentation of the root-complex. This clonal growth strategy, however, was neither clearly ‘phalanx’ nor ‘guerrilla’ type. It resulted in intermittent shallow cavities within fragmented root-stock that got filled with soil rich in organic matter. The growth strategy of the species showed potential to restore the soil system and to conserve the diversity of minor biota. In moderately disturbed sal forest, the understorey paved way to prolific non-seed regeneration of this fugitive mid-successional species. At moderate heat stress, the number of individuals as well as the proportion of seedlings per population was highest. The species rapidly increased the understorey foliage by producing a metapopulation of usable sprouts/ramets that facilitated retention of soil and nutrients within their root traps. The total extractible shoot biomass per plant was quite large as a ~ 6 year old individual weighed 473.5 ± 27.4 g. This study of clonal plant ecology may provide new impetus to the conservation of degraded forest ecosystems.

Indicators of the nitrogen nutritional status of sugarcane submitted to nitrogen rates

Diagnosis of the nutritional status of sugarcane is an important complementary tool for management of fertilization. The objective of this study was to evaluate nitrogen nutritional status of sugarcane submitted to nitrogen rates by conventional method and alternatives indicators. The experiment was conducted in a greenhouse with the IACSP95 5000 cultivar, grown in 20 L pots containing sand and vermiculite. The treatments consisted of six nitrogen rates (0, 5, 10, 20, 40, 80 mg dm -3 of N) using urea as a source. From ten to fourteen days after fertilization, nine productive, nutritional and physiological parameters were evaluated and correlated (shoot dry weight, root dry weight, N content in leaves, total shoot N content, total shoot N accumulation, nitrate content in leaves, NR activity, chlorophyll index in type 0 leaf and chlorophyll index in type +1 leaf). All nutritional, physiological and productive indicators, with the exception of the root biomass, were affected by the variation in the nitrogen supply. There was a high correlation between nitrate reductase enzyme activity and chlorophyll content with leaf N content, suggesting a high potential to indicate the nutritional status of sugarcane.

Lucerne (Medicago sativa) alters N2O-reducing communities associated with cocksfoot (Dactylis glomerata) roots and promotes N2O production in intercropping in a greenhouse experiment

Lower emissions of the greenhouse gas nitrous oxide (N2O) are generally observed from intercropped compared to sole cropped systems. This could be due to better N-use efficiency, but differences in microbial communities establishing in the rhizosphere may also play a role as the only known biological sink for N2O is its reduction to nitrogen gas (N2) by bacteria and archaea that possess the nosZ gene encoding the N2O reductase. Nitrous oxide reducing communities can be divided into two clades, I and II, and their relative abundance and diversity may have important consequences for N2O emissions. Here, we examine how intercropping with a legume (Medicago sativa, “lucerne”) and a grass (Dactylis glomerata, “cocksfoot”) species, compared to sole cropping of each species, affects the N2O emission potential, and the structure and abundance of root-associated N2O-reducing microbial communities. In a rhizobox experiment, we show that intercropping resulted in higher total shoot biomass compared to sole cropping. Further, N2O production rates were significantly higher in intercropped cocksfoot roots compared to sole cropping of either species. This coincided with lower abundances of nosZ clade II communities in intercropped compared to sole cropped cocksfoot roots, suggesting that these organisms likely act as a N2O sink. Phylogenetic placement of sequencing reads placed root-associated nosZ clade II reads close to Ignavibacteria and Opitutaceae, which harbour non-denitrifying N2O reducers with the genetic capacity to also perform dissimilatory nitrate reduction to ammonium (DNRA). We observed a shift in the composition of the cocksfoot root-associated nosZI communities towards incomplete denitrifiers terminating with N2O in intercropped roots. Overall, we hypothesize that such alterations of plant-microbe and/or microbe-microbe interactions contributed to the higher potential N2O emission rate observed in intercropped cocksfoot roots. Understanding the nature of these interactions would represent an important step forward for the design of management practices that minimize N2O emissions.

Extratos de espécies florestais como alternativa no controle de tiririca (Cyperus rotundus)

O objetivo desse estudo foi avaliar o efeito alelopático do extrato de folhas das espécies florestais leucena e algaroba, em diferentes concentrações, na germinação e crescimento inicial da planta infestante Cyperus rotundus (tiririca). O experimento foi conduzido em delineamento inteiramente casualizado com arranjo fatorial 3 x 4, com quatro repetições. O primeiro fator foi representado por dois tipos de extrato de espécies florestais: algaroba (Prosopis juliflora) e leucena (Leucaena leucocephala), e um nível sem aplicação de extrato. O segundo fator foi representado por quatro diferentes concentrações de cada extrato, 25%, 50%, 75%, e 100% p v-1. Foram avaliados o número de brotações emergidas a cada dia, percentual de emergência após 21 dias da realização do plantio, índice de velocidade de emergência das plântulas, comprimento da parte aérea das plântulas, matéria fresca e matéria seca da parte aérea das plântulas. Houve efeito significativo (p&lt;0,05) dos extratos e de suas concentrações sobre o crescimento da planta infestante, interferindo no comprimento da parte aérea das plântulas de tiririca, e efeito significativo (p&lt;0,01) dos extratos sobre a massa fresca e seca total da parte aérea. Contudo, os demais parâmetros não foram influenciados pelos extratos e pelas diferentes concentrações. Não foi comprovada a eficácia dos extratos das espécies florestais, algaroba e leucena, como bioherbicidas no controle de plantas de plantas infestantes Cyperus rotundus.

Abscisic acid alters carbohydrate accumulation induced by differential response to sodium salts in the halophyte Prosopis strombulifera

The role of abscisic acid (ABA) was analyzed in roots and leaves of the halophyte Prosopis strombulifera in response to low osmotic potential (Ψo: −1.0, −1.9, and −2.6 MPa) induced by sodium chloride (NaCl), sodium sulfate (Na2SO4), and the iso-osmotic combination of both compounds (NaCl + Na2SO4). P. strombulifera plants were sprayed with ABA, as well as with inhibitors of ABA biosynthesis (sodium tungstate and fluridone). Different parameters were measured, including total plant height, leaf number, root length, root and shoot biomass, water content, transpiration rate, and total soluble carbohydrates, specific carbohydrates and ABA concentrations. Results showed that sodium salts affected growth parameters in varying ways, depending on the type of salts used as well as the osmotic potentials. ABA-sprayed plants displayed the lowest transpiration values. These plants had a higher content of total soluble carbohydrates in roots, greater root biomass and length and increased root/shoot rate. This study shows that ABA triggers different biochemical and physiological responses after the perception of a stressful condition, and that the interaction between different concentrations and types of salts, and the addition of ABA or its inhibitors generates responses that affect development and growth in the halophyte P. strombulifera.

The Effect of Pyraclostrobin Application on Yield of Tea (Camelia sinensis (L.) O. Kuntze) under Wet Season

This field experiment aimed to study the effect of pyraclostrobin on tea production and to determine optimum concentration in order to maintain high yield during the period of wet season. The experiment was arranged in Randomized Completely Block Design (RCBD) using single factor and three blocks as replications. The pyraclostrobin doses, consisted of 4 levels, 0, 50, 100, and 150 g.ha-1, each will be tested on three tea clones. Clones tea tested are TRI 2025, Gambung 9 and PGL 15. Data was evaluated for chlorophyll content, photosynthetic rate, number of pecco, number of dormant shoot (banjhi), number of total shoot, pecco fresh weight, banjhi fresh weight, total shoot fresh weight, and shoot dry weight. Data were analysed by using Analysis of Variance (ANOVA) and LSD test at α = 5%. The results informed that pyraclostrobin was able to improve chlorophyll content on TRI 2025 clone, and improved photosynthetic rate on Gambung 9 clone. However, there was no significant different among plants treated with pyraclostrobin on a yield components, i.e., number of pecco, number of banjhi, pecco fresh weight, banjhi fresh weight, total shoot fresh weight, and total shoot dry weight.

Sodium in the leaf apoplast does not affect growth of maize (Zea mays L.) under saline field conditions

Studies dealing with leaf apoplastic Na+ concentration of monocots, such as maize, under actual saline soils are scarce. Therefore, the current study was aimed to investigate the growth, total ions and leaf apoplastic Na+ concentration of salt sensitive maize plants growing in saline soils. Plants were subjected to salt stress with an electrical conductivity (EC) of 3, 8 10 and 14 dS m-1 using completely randomized design (CRD) for 3 weeks. Shoot fresh weight, plant height, leaf area and leaf length of maize plants drastically decreased when plants were exposed to increasing salt stress. We found that maize could display a steep increase in Na+ concentration in the total shoot biomass with maximum 82.3 μmol g-1 FW, when plants were subjected to highest soil salinity at 14 dS m-1. As expected, other cations i.e., K+, Ca2+ and Mg2+ decreased with increasing EC of the soil compared to Na+. Surprisingly, a maximum of 17 mM Na+ were found in the leaf apoplast of maize grown under very high soil salinity at EC 14 dS m-1. Considering this lower leaf apoplastic Na+ concentration at such a high EC level in maize plants, current study does not corroborate that surplus sodium in the leaf apoplast can result in dehydration and cell death under salt stress.

The response of glyphosate-resistant and glyphosate-susceptible biotypes of junglerice (Echinochloa colona) to mungbean interference

AbstractGlyphosate-resistant junglerice [Echinochloa colona (L.) Link] is a problematic weed in mungbean [Vigna radiata (L.) R. Wilczek] crops in Australia. Due to limited herbicide options in mungbean, there is an increased interest in developing integrated management strategies for the sustainable control of E. colona. Pot experiments were conducted in a screenhouse in 2017 and 2018 by growing E. colona plants (glyphosate-resistant [GR] and glyphosate-susceptible [GS] biotypes) alone (1 plant pot−1) and in competition with 4 and 8 mungbean plants pot−1. Both biotypes were developed from a single population using the clone method. The growth and seed production of both GR and GS biotypes were similar in response to mungbean competition. Averaged over biotypes, there was a reduction in the growth and seed production of E. colona as crop plants increased. Compared with the weed plants grown alone, crop interference reduced E. colona height by 17% to 19%, tiller numbers by 69% to 82%, total shoot biomass by 85% to 91%, and inflorescence numbers by 74% to 91%. When E. colona was grown with 8 mungbean plants pot−1, leaf weight ratio increased by 42% compared with plants grown alone. Compared with weed plants grown alone, mungbean interference (4 and 8 plants pot−1) reduced weed seed production by 85% to 95%. These reductions were similar for both biotypes (GR and GS), suggesting that there was no fitness penalty associated with resistance. The results of this study suggest that mungbean interference can reduce E. colona growth and seed production, but it should not be considered as a stand-alone strategy to manage E. colona and similar species in mungbean. These results also highlight the need for integrating crop competition with other management strategies to achieve complete and sustainable management of this weed.

The response of glyphosate-resistant and glyphosate-susceptible biotypes of junglerice (Echinochloa colona) to mungbean interference

AbstractGlyphosate-resistant junglerice [Echinochloa colona(L.) Link] is a problematic weed in mungbean [Vigna radiata(L.) R. Wilczek] crops in Australia. Due to limited herbicide options in mungbean, there is an increased interest in developing integrated management strategies for the sustainable control ofE. colona. Pot experiments were conducted in a screenhouse in 2017 and 2018 by growingE. colonaplants (glyphosate-resistant [GR] and glyphosate-susceptible [GS] biotypes) alone (1 plant pot−1) and in competition with 4 and 8 mungbean plants pot−1. Both biotypes were developed from a single population using the clone method. The growth and seed production of both GR and GS biotypes were similar in response to mungbean competition. Averaged over biotypes, there was a reduction in the growth and seed production ofE. colonaas crop plants increased. Compared with the weed plants grown alone, crop interference reducedE. colonaheight by 17% to 19%, tiller numbers by 69% to 82%, total shoot biomass by 85% to 91%, and inflorescence numbers by 74% to 91%. WhenE. colonawas grown with 8 mungbean plants pot−1, leaf weight ratio increased by 42% compared with plants grown alone. Compared with weed plants grown alone, mungbean interference (4 and 8 plants pot−1) reduced weed seed production by 85% to 95%. These reductions were similar for both biotypes (GR and GS), suggesting that there was no fitness penalty associated with resistance. The results of this study suggest that mungbean interference can reduceE. colonagrowth and seed production, but it should not be considered as a stand-alone strategy to manageE. colonaand similar species in mungbean. These results also highlight the need for integrating crop competition with other management strategies to achieve complete and sustainable management of this weed.

Effect of elevated carbon dioxide on plant biomass and grain protein concentration differs across bread, durum and synthetic hexaploid wheat genotypes

Atmospheric carbon dioxide conditions predicted for future climates cause increases in wheat biomass, but also decreases wheat grain protein concentration. We investigated the response of grain protein concentration of wheat to elevated carbon dioxide in nineteen wheat genotypes, including five tetraploid, eleven hexaploid and three synthetic hexaploid genotypes to test whether decreased grain protein is genotype dependent and whether it is caused by biomass dilution. These were grown in ambient and elevated carbon dioxide conditions simultaneously. Shoot biomass and grain samples were taken at maturity. The grain protein concentration, grain biomass, shoot biomass and harvest index were analysed for each genotype. Despite most genotypes increasing in total grain protein (g), the majority of genotypes decreased in grain protein concentration (%) under elevated carbon dioxide. Elevated carbon dioxide caused an increase in grain biomass for all genotypes and total shoot biomass for most genotypes, with harvest index increasing for all genotypes except the two synthetic hexaploids CPI133814 and CPI133811. Most of the differences between wheat types were not statistically significant, suggesting that the individual genotype of wheat plants determines the response to elevated carbon dioxide rather than the wheat type.

High-throughput 3D modelling to dissect the genetic control of leaf elongation in barley (Hordeum vulgare).

SummaryTo optimize shoot growth and structure of cereals, we need to understand the genetic components controlling initiation and elongation. While measuring total shoot growth at high throughput using 2D imaging has progressed, recovering the 3D shoot structure of small grain cereals at a large scale is still challenging. Here, we present a method for measuring defined individual leaves of cereals, such as wheat and barley, using few images. Plant shoot modelling over time was used to measure the initiation and elongation of leaves in a bi‐parental barley mapping population under low and high soil salinity. We detected quantitative trait loci (QTL) related to shoot growth per se, using both simple 2D total shoot measurements and our approach of measuring individual leaves. In addition, we detected QTL specific to leaf elongation and not to total shoot size. Of particular importance was the detection of a QTL on chromosome 3H specific to the early responses of leaf elongation to salt stress, a locus that could not be detected without the computer vision tools developed in this study.

Charophytes collapse beyond a critical warming and brownification threshold in shallow lake systems

Charophytes play a critical role for the functioning of shallow lake ecosystems. Although growth of charophytes can be limited by many factors, such as temperature, nutrients and light availability, our understanding about concomitant effects of climate warming and other large-scale environmental perturbations, e.g. increases in humic matter content (‘brownification’) is still limited. Here we conducted an outdoor mesocosm experiment during 71days with a common charophyte species, Chara vulgaris, along an increasing gradient of temperature and brownification. We hypothesized the growth of C. vulgaris to increase with temperature, but to level off along the combined temperature and brownification gradient when reaching a critical threshold for light limitation via brownification. We show that C. vulgaris increases the relative growth rate (RGR), main and total shoot elongation, as well as number of lateral shoots when temperature and brownification increased by +2°C and+100%, respectively above today's levels. However, the RGR, shoot elongation and number of lateral shoots declined at further increment of temperature and brownification. Macrophyte weight-length ratio decreased with increased temperature and brownification, indicating that C. vulgaris allocate more resources or energy for shoot elongation instead of biomass increase at warmer temperatures and higher brownification. Our study shows that C. vulgaris will initially benefit from warming and brownification but will then decline as a future scenario of increased warming and brownification reaches a certain threshold level, in case of our experiment at +4°C and a 2-fold increase in brownification above today's levels.

Response of potted anthurium (Anthurium andreanum Lind.) to the K+: Ca+2: Mg+2 balance in the nutrient solution

The climatic conditions of the humid tropical areas of México allow the year-round production of cut flowers and potted plants of anthurium. However, the scarce basic and applied research on tropical ornamental species limits the development of technology to increase productivity and quality. In this article, we are reporting the information as to the effect of the proportions of potassium (K+), calcium (Ca+2), magnesium (Mg+2) in the nutrient solution on anthurium growth using mixture analysis and response surface methodology. The sum of all the three cations was 20 meq L−1 and each one is expressed as a fraction of this total concentration. Response surface analysis detected that spathe and leaf areas decreased in plants fed with solutions of high proportions of Mg+2. Total shoot and root fresh weight, as well as total dry weight and root volume, also demonstrated the deleterious effects of high Mg+2. In general, the best growth occurred in two areas of the explored space; a) an area of high Ca+2, with optimum proportions ranging from 0.24–0.44 for K+, 0.54–0.68 for Ca+2, and 0.01–0.08 for Mg+2, and b) another area of high K+, on which the optimum proportions ranged 0.54–0.65 for K+, 0.25–0.29 for Ca+2, and 0.10–0.21 for Mg+2. Shoot and root K+, Ca+2, and Mg+2 concentration was significantly affected by the cation balances in the external solution, however, there was not a clear tendency as to the effect of each cation in the mixture; nonetheless, the internal K+: Ca+2: Mg+2 balances were affected by the balances in the nutrient solution, as in the shoot they were located in a very specific area of the explored space, indicating that anthurium plants accumulated more Mg+2 compared to what it is in the external solution, whereas Ca+2 was lower than that of the external solution. Plants accumulated K+ at high rates regardless of the external balance. In conclusion, the optimum nutrient solutions for anthurium may contain very wide ratios of K+ as long Ca+2 and Mg+2 are maintained at low proportion in the nutrient solution.