Biomass Partitioning Research Articles

Winter Wheat Crop Models Improve Growth Simulation by Including Phenological Response to Water-Deficit Stress

AbstractCrop models can provide insights into the impacts of climate and management on crop growth and yield, but most currently are limited by overly simplistic assumptions about phenological development and response to water stress. We assessed winter wheat growth and yield performance of three crop models with lineage to the EPIC crop submodel. SWAT adopted the EPIC approach with few modifications, WEPS added new biomass accumulation, partitioning, and canopy approaches linked to key phenological development stages, and UPGM added to WEPS a detailed phenology component simulating responses to water-deficit stress. The models were evaluated with default parameters and compared to experimental data for winter wheat (Triticum aestivum L.) from two sites and a range of water-stress conditions for yield, aboveground biomass, biomass partitioning, canopy height, harvest index, and leaf area index. All models simulated yield very well (index of agreement [d] ≥ 0.93), but differences in model performance were increasingly evident for biomass (d = 0.91 [WEPS] to 0.86 [SWAT]), final canopy height (d = 0.68 [UPGM] to 0.44 [SWAT]), and harvest index (d = 0.61 [WEPS] to 0.43 [SWAT]). Errors in biomass simulation were most evident in the grain-filling period late in the growing season. Both WEPS and UPGM exhibited improved simulation of biomass and other response variables by including more explicit simulation of phenological response to water stress. The consistent improvement in winter wheat growth and yield simulation achieved with detailed phenology simulation provides an incentive to develop and test detailed phenology simulation components for other crops: currently 11 crops are simulated in UPGM, although the phenological parameters are uncalibrated. Better modeling linkages of water-stressed phenological development with other physiological processes will be critical to inform crop production where water stress and irrigation limitation are concerns.

The Impact Study of Anti-Radiation Biomass Material on Partition Wall Absorption Performance

With the increasing public concern over radiation exposure and its potential health risks, exploring practical solutions for mitigating radiation in various environments is essential. This study aims to raise awareness about radiation-related issues by investigating the impact of anti-radiation biomass material on the reflectivity performance of partition walls. By incorporating this biomaterial into partition walls, we examine how radiation absorption capabilities can be improved, enhancing overall radiation safety. The process entails combining the biomass material, Palm Oil Fuel Ash (POFA), cement, aluminum, and water in the proper ratios to create a composite material. The combined material is subsequently shaped into partition walls. The anti-radiation biomass partition wall's reflectivity performance was measured using the Naval Research Laboratory (NRL) Arch free space method, with frequencies between 1 GHz and 12 GHz utilised in this project. The study showed that the anti-radiation biomass partition wall containing 35% POFA demonstrated the best reflectivity performance.

High post-flowering phosphorus status promotes the tolerance of soybean to terminal heat stress

Global air temperature is rising and resulting in higher frequency and intensity of extreme climatic events. This scenario threatens food security, requiring measures to mitigate the harmful effects of heat stress on agricultural production. Therefore, our study focused on understanding how phosphorus (P) availability during the reproductive period affects seed weight responses of soybean to terminal heat stress. The experiment was carried out in a complete 3 × 2 factorial design, with varying post-flowering P supply (severe deficiency: 20 μmol P L−1; mild deficiency: 100 μmol P L−1; sufficiency: 500 μmol P L−1) and thermal regimes imposed during the seed filling phase (control: 28.0/18.0 °C; heat stress: 42.0/28.5 °C). Our results revealed that seed weight and yield were unaffected by heat stress in the plants grown under P sufficiency, whereas a detrimental effect of warming on these traits was found in the plants facing post-flowering P deficiency. Sufficient post-flowering P supply alleviated also the harmful effects of heat stress on the integrity of the photosynthetic apparatus, which contributed to improve biomass partitioning to the harvestable organs by extending seed filling duration. Moreover, heat stress disturbed sink metabolism and caused reduction in the concentration of oil and starch solely in the seeds of the plants exposed to P limitation. In conclusion, maintaining adequate post-flowering P supply proves critical in enhancing soybean’s tolerance to terminal heat stress by supporting essential processes involved in effective seed filling. Consequently, implementing precise P nutritional management during the reproductive period of soybean might be a promising approach to improve crop yield stability in challenging environmental conditions.

Germination and biomass partitioning in creole varieties of cowpea (Vigna unguiculata (L.) Walp.) under salinity conditions

Saline soils can limit seedling germination and growth of the crops. This research sought to identify whether the cowpea varieties Pingo-de-ouro and Coruja are tolerant to salinity in terms of germination and biomass partitioning. A completely randomized design in a 2 x 4 factorial arrangement, totaling eight treatments with four replications was used. The treatments consisted of two varieties of cowpea in addition to NaCl salinity with four levels of electric conductivity (0.0, 3.3, 6.6 and 9.9 dS∙m-1). The variables analyzed were percentage of germination (PG), first germination count (FGC), germination speed index (GSI), average germination time (AGT), percentage of seedling (PSB), shoot (PSHB), root (PRB) and cotyledon (PCotB) biomass, PCotB/PSB ratio and salinity tolerance index (STI). The Pingo-de-ouro variety showed tolerance to 3.3 dS∙m-1 displaying an increase in PSB and PSHB, while the Coruja variety tolerated 6.6 dS∙m-1 with a more significant investment in PRB. Both displayed no significant statistical reduction in percentage of G, FGC, GSI, AGT, and STI up to 3.3 dS∙m-1 for the Pingo-de-ouro variety and 6.6 dS∙m-1 for the Coruja one. Thus, those genetic materials can be used to breed tolerant plants. The present research also provides results for further studies at physiological, molecular, and field conditions.

Terminal removal at first square enhances vegetative branching to increase seedcotton yield at low plant density

ContextCotton has a complex branching pattern including sympodial and vegetative branching. Traditionally managed cotton mainly depends on sympodial branching for formation of yield-contributing fruit. Whether seedcotton yield based solely on vegetative branching is comparable with that based solely on sympodial or both types of branching is unclear. ObjectiveThe study determined how terminal removal at first square to avoid formation of sympodial branches (SBs) regulated vegetative branching and yield under different plant densities. MethodsA two-year split-plot design field experiment had main plots with plant density (4.5 and 9.0 plants m−2) and subplots with plant pruning mode. Pruning modes were terminal removal at first square (TRS) to avoid formation of sympodial branches but retain only vegetative branches (VBs), removal of VBs (RVB) to retain only SBs, and no pruning (CK), with both branch types remaining intact. Canopy photosynthesis, dry matter accumulation and partitioning, and seedcotton yield and yield components were examined. ResultsAt low plant density (4.5 plants m−2), compared with other pruning modes, TRS increased seedcotton yield and biological yield but did not affect harvest index. At high plant density (9.0 plants m−2), compared with other pruning modes, TRS decreased seedcotton yield and harvest index, although biological yield increased. The yield increase with TRS at low plant density was attributed to the increase in biological yield, which was due to significantly higher canopy photosynthesis with TRS than with other pruning modes. At high plant density, photosynthesis with TRS was higher than that with no pruning at peak boll-setting and boll-opening stages and higher than that with RVB from peak squaring to boll-opening. Compared with other pruning modes, TRS increased dry matter partitioning to vegetative organs but decreased partitioning to reproductive organs. Pearson correlation analysis revealed a significant positive correlation between canopy apparent photosynthesis and biological yield, biomass partitioning, and harvest index, irrespective of plant pruning and plant density. ConclusionPlant pruning and plant density interacted to affect seedcotton yield. With TRS, cotton yield at low plant density was higher than that with other pruning modes, which was attributed to an increase in biological yield associated with an increase in canopy photosynthesis. At high plant density, the yield decrease with TRS was attributed to low harvest index associated with reduced reproductive partitioning. ImplicationsCotton cultivation relying solely on vegetative branching can be an alternative to obtain moderate yields and economic benefits under conditions of low plant density.

Exploring the Growth and Development of Rambutan (Nephelium lappaceum L.) Seedlings: The Impact of Fruit Maturation on Seed Germination, Seedling Growth and Biomass Partitioning

Background: Rambutan (Nephelium lappaceum L.) is one of the most important tropical commercial fruits widely cultivated in south-east Asia, Australia, South America, and African countries due to its nutritional value. However, in Ghana the fruit is gaining popularity in many households and, this could serve as an alternative source of income. The experiment was conducted at the CSIR-Plant Genetic Resources Research Institute, Bunso, Eastern region-Ghana. The objective of the study was to evaluate the effects of maturity stages on Rambutan seed vigour, germination, seedling growth and biomass partitioning. Methods: Fruits of three maturity stages (i.e. green, half-ripe and fully ripe) were harvested from the field genebank and seeds extracted and sown immediately after harvest. The experiment was arranged in a randomised complete block design in three replicates. Results: The results showed that fully ripe fruits had better seed vigour, seedling growth and biomass partitioning followed by the half-ripe fruits. Fruits harvested at the green stage showed the least performance.

Genotypic stability in root system architecture and aboveground biomass revealed diverse adaptability of peanut (Arachis hypogaea L.) to moderate water deficit

AbstractMany crop species, including cultivated peanut (Arachis hypogaea L.), modify their above‐ and below‐ground growth to cope with water deficit stress. This acclimation to water deficit often triggers a biomass partitioning shift—allocating more biomass to the roots, to increase the accessibility of roots to water resources. However, additional carbon partitioning to roots may not always translate into increased water use and maintenance of aboveground biomass (ABM) and yield. Therefore, selecting an efficient root system architecture (RSA) should aim to sustain a high ABM production under a water deficit scenario. To better understand the associations of above and belowground biomass partitioning under moderate water deficit, this study evaluated the genotypic stability of 40 peanut genotypes in ABM and RSA in greenhouse experiments and further assessed genotypic differences in 4 site‐year field experiments. Our results suggested that higher ABM‐producing genotypes generally had high plasticity when subjected to water deficit whereas the low ABM‐producing genotypes had relatively high stability. Hierarchical clustering analysis further revealed that genotypes with a high root‐to‐shoot ratio potentially had increased genotypic stability in ABM underwater deficit. Interestingly, genotypes that maintained the highest ABM underwater deficit did not have the highest total root biomass and length. Instead, these genotypes had the highest root length in the top layer of soil (0–0.3 m) and relatively fewer roots in the deeper layer of soil (0.3–1 m). Greenhouse‐screened stable genotypes exhibited minimal yield reduction when subjected to mid‐season water deficit in some of the field validation experiments, but it also happened to some plastic genotypes, indicating that further validation of controlled environment screenings for genotypic water‐deficit tolerance in the field is necessary.

65 years of cotton lint yield progress in the USA: Uncovering key influential yield components

Context or problemCotton is an essential cash crop with significant importance in industries related to fiber, feed, and oil. However, achieving further improvements in cotton lint yield requires a more comprehensive understanding of different biomass components and the development of targeted management strategies. Objective or research questionThe objective of this study was to assess the biomass partitioning of 20 cotton cultivars released between 1953 and 2018, determine the rate of gain for lint yield, and identify the contribution of biomass components to yield performance. MethodsA two-year field experiment was conducted to evaluate the biomass partitioning of the 20 cotton cultivars released between 1953 and 2018. Correlation, linear, and path analyses were performed to estimate the effects of various biomass components (such as leaf, stem, bolls, burs, seed, and lint harvest index) on lint yield. ResultsThe study found that lint percentage, lint harvest index, seed biomass, and total aboveground biomass and its components exhibited a linear increase with the year of release. However, improving total aboveground biomass alone without enhancing reproductive partitioning could lead to a decrease in lint yield. Furthermore it was observed that the efficiency of modern cultivars in partitioning aboveground biomass into different plant parts, except for lint, has remained unchanged over the past 65 years of breeding. ConclusionsThe results suggest that future research should prioritize improving the lint harvest index to further enhance the potential lint yield of cotton. Merely increasing total aboveground biomass may not yield the desired improvements in lint yield. Optimizing reproductive partitioning is crucial for achieving enhanced lint yield. Implications or significanceThis study provides valuable insights into the biomass partitioning and yield performance of cotton cultivars spanning several decades. The findings emphasize the importance of focusing on improving the lint harvest index as a key factor in increasing lint yield. The results have implications for the development of targeted management strategies in cotton production and breeding programs, contributing to the overall sustainability and productivity of the cotton industry. Data AvailabilityThe datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Pre-anthesis spike growth dynamics and its association to yield components among elite bread wheat cultivars (Triticum aestivum L. spp.) under Mediterranean climate

Wheat (Triticum spp.) grain yield (GY) is highly associated with grain number per unit area (GN m-2). Biomass accumulation and partitioning are essential to understand pre-anthesis spike growth dynamics which determines spike dry matter at anthesis (SDMa) - a GN determinant. Spike growth takes place during the stem elongation period (SE), from terminal spikelet to anthesis, following leaf and spikelet initiation (LS) from sowing to terminal spikelet. In this study, bread wheat cultivars were examined under Mediterranean semi-arid conditions to determine (i) the varietal differences in pre-anthesis phase duration, (ii) whether this variability influences biomass partitioning and spike-related traits, and (iii) to what extent, the genotypic variations in pre-anthesis phase duration and spike growth are associated with yield components. A panel of Israeli commercial bread wheat cultivars were grown in the field during 2016–17 (three environments) and 2017–18 (two environments) and characterized for pre-anthesis phases, floral conditions and spike fertility via histological measurements; spike traits, dry matter accumulation, partitioning at anthesis and maturity and for yield components. Significant variability in the timing of pre-anthesis phases was detected within the tested panel for both LS and SE phases. LS duration was positively associated with growing degree days (GDD) to anthesis across environments (0.72–0.90) while variation in SE was related with differences in GDD to anthesis but to a lesser extent and not in all environments (0.47–0.79). In addition, LS duration, and occasionally SE, were favourably related with a higher dry matter of fertile florets spike-1 (at anthesis) and SDM (at both anthesis and maturity). Principal component analysis (PCA) clearly separates environments and to a lesser extent cultivars within each environment. Two cultivar pairs 'Zahir-Yuval' and 'Negev-Gedera', which flowered concurrently, showed significant differences in the durations of LS and SE phases across most of the environments. Longer LS, in cultivars Zahir and Negev, exhibited increased spikelets spike-1, whereas longer SE (e.g., in Yuval and Gedera) enhanced spike fertility through improving the survival rate of floret primordia (FSR%) of central spikelets. However, there was a trade-off for FSR at the proximal and distal spike portions, resulting in lower grain set (%) leading to reduction of final GN (or GY) in cultivars with longer SE. In the tested panel and under our environmental conditions characterized by growing cycle and Mediterranean climate, the duration of both LS and SE contribute to spike fertility, but LS duration seemed a stronger driver than SE for GN and yield enhancement. Our results highlight the importance of pre-anthesis phases, especially the role of LS in wheat yield increment during the short growing cycle. The varietal combination with variable LS and SE duration could be implemented in breeding pipelines and used as pre-breeding materials for GN improvement. Furthermore, the findings will encourage pre-anthesis traits adoption in Mediterranean bread wheat future breeding programs.

Developing Functional Relationships between Soil Moisture Content and Corn Early-Season Physiology, Growth, and Development.

Drought is a severe threat to agriculture production that affects all growth stages of plants, including corn (Zea mays L.). Any factor affecting early seedling growth and development will significantly impact yield. Despite the recurrence of low rainfall during the growing seasons, corn responses to different early-season soil moisture content levels have not been investigated. In this study, we investigated how corn morpho-physiological and biomass traits responded to varied soil moisture content during the early vegetative stage. Two corn hybrids were grown in a pot-culture facility under five different soil moisture treatments (0.15, 0.12, 0.09, 0.06, and 0.03 m3 m-3 volumetric water content, VWC) to assess the growth and developmental responses to varied soil moisture content during early-season growth (V2 to V7) stage. Sub-optimal soil moisture content limited plant growth and development by reducing physiological and phenotypic expression. Stomatal conductance and transpiration were decreased by an average of 65% and 59% across stress treatments relative to optimum conditions. On average, soil moisture deficit reduced the total leaf area by 71% and 72% compared to the control in 'A6659VT2RIB' and 'P1316YHR', respectively. Shoot and root dry weights were reduced by 74% and 43% under 0.03 m3 m-3 VWC. An increase in the root-to-shoot ratio was noticed under low VWC conditions compared to the control. Based on the stress tolerance index, the physiology and leaf growth parameters were more sensitive to soil moisture deficit. Our results highlight the impact of sub-optimal soil moisture on physiology and morphological traits during early-season growth. 'P1316YHR' demonstrated better physiological performance under stress conditions, while 'A6659VT2RIB' produced relatively better root growth. The findings suggest that biomass partitioning between shoot and root components is dynamic and depends on stress intensity. The current findings can help to prioritize traits associated with the early-season drought tolerance in corn. The functional relationships developed between soil moisture content and growth and developmental responses can be integrated into corn crop modeling to allow better irrigation management decisions.

Biomass partitioning, yield and economic performance of green gram (Vigna radiate L.) genotypes as influenced by different irrigation levels

A field experiment was conducted during the Kharif season of2020 with four main plot treatments consisting of irrigation levels (No post sowing irrigation, one irrigation at the flower initiation stage, one irrigation at the pod filling stage and two irrigations each at flower initiation and pod filling stage) and five subplot treatments as genotypes viz., MH 1142, MH 1468, MH 1703, MH 1762 and MH 1871 following split plot design by replicating thrice. Irrigating green gram, irrespective of the growth stage, increased the seed yield significantly. Two irrigations each at the flower initiation and podding stage bring about greater seed economic yield of green gram than 1 irrigation either at each stage. Among single irrigations, flower initiation stage provided significantly superior (8.6 %) seed yield compared to the pod filling stage. During the flower initiation stage, no rain and irrigation at this stage led to more development of crop plants, as is evident from a higher number of branches per plant and, ultimately, a higher number of pods. Two irrigations, i.e., each at flower initiation and podding phase, lead to considerably greater seed output than single irrigation at either growth stage, which may be attributed to the sufficient supply of water, which indirectly provided a smooth supply of nutrients to crop plants. The increase was 18.4 and 28.6 per cent over-irrigation at flowering and podding stage, respectively. Seed yield varied among green gram genotypes, which might be because of variations in the genetic potential of the genotypes. Genotype MH 1871 produced significantly higher seed yield among different genotypes. The cumulative effect of yield traits viz. pods per plant, branches per plant, seed index and seeds per pod attributed to the higher seed yield in MH 1871. This genotype was more efficient in utilizing radiations, as evident from the higher chlorophyll content recorded in this genotype. Genotype MH 1142 was the lowest yielder and MH 1762 although produced. To obtain a higher yield of green gram, genotype MH 1871 be taken with two irrigations each at flower initiation and pod filling stage.

Asymmetric response of above- and below ground biomass of C3- and C4-dominated grasslands to aridity

Abstract Assessing the dynamics of grassland functioning is critical for gaining an understanding of their feedback on rising aridity. In attempting to understand the response of grassland ecosystem functioning to aridity, the (i) relationships between biomass productivity (above- and belowground biomass: AGB and BGB, and their partitioning: BGB:AGB) and seasonal and annual aridity, and (ii) biomass allocation pattern between the AGB and BGB of C3- and C4-dominated grasslands in humid temperate, humid savanna, cold steppe, and savanna ecoregions were assessed. Results reveal that biomass productivity and its partitioning responded significantly to differences in growing season aridity, but the response patterns were not consistent for ecoregions. The decreased annual and seasonal biomass partitioning in humid savanna and cold steppe was associated with increased AGB and decreased BGB with accelerated aridity. There was a significant positive correlation in the biomass allocation pattern between the AGB and BGB of plants in three ecoregions, which supports the optimal partitioning theory. This study reveals that growing season aridity, rather than annual aridity, is the primary factor of biomass productivity and partitioning in the studied grasslands. These findings have significant repercussions for predicting ecosystem functioning and stability, restoring degraded ecosystems, and ensuring the sustainable management of grassland biodiversity.

Biomass partitioning and physiological responses of four Moroccan barley varieties subjected to salt stress in a hydroponic system

Biomass partitioning and physiological responses of four Moroccan barley varieties subjected to salt stress in a hydroponic system

Fromforest floor to tree top: Partitioning of biomass and carbon stock in multiple strata of forest vegetation in Western Himalaya.

The foremost role of forest vegetation in storing biomass and carbon (C) stock constitutes one of the main nature-based solutions to mitigate climate change. In this study, we aimed to quantify biomass and C stock partitioning in multiple vegetation strata (tree, shrub, herb, and ground floor layers) of major forest types in Jammu and Kashmir,Western Himalaya, India. We used a stratified random cluster sampling strategy to collect field data in 96 forest stands of 12 forest types (altitudinal range: 350 to 3450m) in the study region. We evaluated the degree to which the carbon stock of the entire ecosystem was dependent on the multiple vegetation strata using the Pearson method. Across all the forest types, the average total ecosystem-level biomass was estimated to be 181.95 Mgha-1 (range: 60.64-528.98). Forest strata-wise, the maximum biomass of 172.92 Mgha-1 (range: 50.64-514.97) was found in the tree vegetation, followed by 5.58 Mgha-1 (range: 2.59-8.93) in understory vegetation (shrubs and herbaceous), and 3.44 Mgha-1 (range: 0.97 and 9.14) in the forest floor. The total ecosystem-level biomass showed a peak at mid-elevation coniferous forest types, whereas the lowest was observed in low-elevation broad leaved forest types. At the ecosystem-level, on average, the understory contributed 3% and the forest floor 2% to the total C stock across the forest types. The shrub layer contributed up to 80% of total understory C, with the herbaceous layer accounting for the remaining 20%. The ordination analysis clearly shows that anthropogenic and environmental variables significantly (p ≤ 0.002) influence the forest types' C stock in the region. Our findings have significant implications for conserving natural forest ecosystems and restoring degraded forest landscapes in this Himalayan region, which in turn can lead to better carbon sequestration and climate mitigation outcomes.

On the contrasting morphological response to far-red at high and low photon fluxes.

Plants compete for sunlight and have evolved to perceive shade through both relative increases in the flux of far-red photons (FR; 700 to 750 nm) and decreases in the flux of all photons (intensity). These two signals interact to control stem elongation and leaf expansion. Although the interacting effects on stem elongation are well quantified, responses for leaf expansion are poorly characterized. Here we report a significant interaction between far-red fraction and total photon flux. Extended photosynthetic photon flux density (ePPFD; 400 to 750 nm) was maintained at three levels (50/100, 200 and 500 µmol m-2 s-1), each with a range of 2 to 33% FR. Increasing FR increased leaf expansion in three cultivars of lettuce at the highest ePPFD but decreased expansion at the lowest ePPFD. This interaction was attributed to differences in biomass partitioning between leaves and stems. Increased FR favored stem elongation and biomass partitioning to stems at low ePPFD and favored leaf expansion at high ePPFD. In cucumber, leaf expansion was increased with increasing percent FR under all ePPFD levels showing minimal interaction. The interactions (and lack thereof) have important implications for horticulture and warrant further study for plant ecology.

Application of compost tea, co-inoculation and inorganic fertilization on Swiss chard plants

Swiss chard is a horticultural crop with a highly nutritious value. These crops’ production required nutrients, which can be provided through mineral nutrient solutions or biofertilizers. Biofertilizers are products that contain beneficial microorganisms that improve soil quality and that promote plant growth. Additionally, these microorganisms carry out nitrogen fixation and phosphate solubilization. The present work assessed the application of compost tea, co-inoculation (Azospirillum and Glomus), and inorganic fertilizer over the growth (roots, stem, and leaves) and nutrient content in Swiss chard (Beta vulgaris var. Forhook Giant) plants. The present work was carried out in a greenhouse using a randomized complete block design. Swiss chard plants treated with compost tea + inorganic fertilization (CTIF) accumulated more root and stem dry weight (4.06 and 8.10 g respectively), and, on the other hand, the leaf dry weight increased under three treatments: inorganic fertilization (IF), compost tea + co-inoculation (CTCi) and CTIF (12.5, 9.22 and 10.5 g respectively). Leaf area was greater in the IF and CTIF treatments. In Control (C) P and Mg content were higher; CTCi treatment increased the N, K, and Mn content; the co-inoculation (Ci) treatment increased Cu content as well as CTIF treatment increased the Ca, Fe, Zn, and B contents and in a lesser extent also the P, Mg, Cu, and Mn contents. The biomass partitioning coef ficient indicates that in six samples (from a total of seven samples), most of the photosynthates (PS) were used by the plants to form new leaves or to increase the size of the leaves. If an alternative method of fertilization is desired, it is recommended that a combination of biofertilizer and inorganic fertilization should be used, such as, the combination of compost tea and mineral solution that increased the production and the concentration of nutrients in the Swiss chard crop.

Interaction of liming, mineral nitrogen fertilization, and Rhizobium inoculation in biomass partitioning and production of cowpea

Cowpea has great capacity of biological fixation of nitrogen (BFN) in association with Rhizobium. However, it is not known whether the interaction of liming, mineral N fertilization, and Rhizobium-inoculated seeds can modify the efficiency of BFN, and still, result in gains in biomass production and yield in cowpea. This study evaluated the use of liming associated to Rhizobium-inoculated seeds and supplemental mineral N fertilization on the nodulation improvement, biomass production, and on the increase of cowpea grain production. Two experiments were conducted under field conditions in two consecutive years, using the same treatments and experimental design. The treatments were conditioned in a split-plot scheme in randomized blocks with four replications in a 2 × 6 factorial, the first factor being two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and the second factor was considered six conditions of corrective practice and N supply [no N supply and no liming (T1), liming + rhizobium (T2), rhizobium (T3), liming + mineral N (T4), liming (T5), and liming + mineral N + rhizobium (T6)]. Nitrogen concentration and accumulation in the leaves increased with liming and N supply (T2, T4, and T6) and increased dry matter (DM) accumulation in the stem, leaves, shoots, and total DM. The absence of liming limited root length growth, decreased root DM, and the number and DM of nodules thus limiting grain production. Additionally, N fertilization supplemented with Rhizobium-inoculated seeds did not increase grain production. However, the use of liming and the inoculation of seeds with Rhizobium increased plant performance and improved grain yield of both cowpea cultivars.

Breeding crops for enhanced roots to mitigate against climate change without compromising yield

Boosting soil carbon by adding it to the soil, is among climate mitigation strategies. In a viewpoint more than a decade ago, Kell (2011) proposed plant breeding as a tool to develop varieties with larger underground biomass as a method to store carbon in the soil and reverse the trends of increasing atmospheric CO2 concentrations. To this date, the only evidence showing breeding for root traits is in rice. Wheat is well suited to serve this purpose because it is an important crop for food security and is the crop with highest cultivated area in the world. In this study, we developed breeding populations by crossing ‘Penny’ (a donor parent with large root) and ‘Yecora’ (a small root cultivar). Aboveground and belowground biomass partitioning, carbon content, and grain weight were studied in soil under controlled environment. Selection candidates differed significantly for all traits except carbon content. Broad-sense heritability for shoot biomass was 0.75 and for all other traits were equal or above 0.94. The root biomass ranged 0.43–7.72 g, averaging 2.13 g. A considerable range of root/shoot ratio was observed the selection candidates from 0.029 to 0.341, averaging 0.10. Based on LSD test, 13 out of 23 progenies tested in the replicated experiment, had significantly greater root biomass than ‘Yecora’. Among those, there were lines that produced equal or greater grain weight than “Yecora”. BC2 129, for example, showed 8.6-folds greater root biomass compared with ‘Yecora’ yet produced grain weight with no significant difference with that of ‘Yecora’. Similarly, BC2 147, BC2 165, BC2 137, showed 3.1-folds, 2.4-folds, 2.3-folds, respectively, greater root biomass but similar grain weights compared with ‘Yecora’. These lines showed significantly greater root/shoot ratios. Roots collected at physiological maturity showed 40.2%, on average, carbon content per dry biomass. This study showed that given one cycle of breeding involving a donor germplasm from genebank wheat root system can be manipulated to develop germplasm for grain production and simultaneously mitigating climate change by allocating more carbon in soil.

The Importance of Initial Seedling Characteristics in Controlling Allocation to Growth and Reserves under Different Soil Moisture Conditions

After disturbance, forest regeneration and resiliency depend on the ability of seedlings to respond, survive, and grow under a variety of stress conditions, including drought. Despite recent efforts to improve our fundamental knowledge surrounding plant response mechanisms to stress and their application in seedling quality research, initial seedling characteristics are often ignored when exploring seedling responses to stress in field plantings or ecophysiological studies. Here, we explore how initial differences in size, biomass allocation, and non-structural carbohydrate (NSC) storage affect the subsequent partitioning of new biomass, growth potential, and drought response in seedlings of a deciduous broad-leaved (Populus tremuloides) and an evergreen coniferous species (Pinus banksiana). We exposed seedlings of both species to different growing conditions in their first growing season in order to manipulate the aforementioned seedling characteristics. In a second growing season, we exposed these different seedling types to a subsequent drought stress. While drought reduced both structural growth and NSC storage in all seedling types, the expected shift in allocation favoring roots was only observed in seedling types with initially low root:shoot or root:stem ratios. Overall, we also found that the traits associated with greater growth were quite different between pine and aspen. While larger seedlings led to greater growth in pine, it was the smallest seedling type in aspen with the largest root:stem ratio that produced the most new growth. In aspen, this smaller seedling type was the only one that did not undergo a shift in biomass relative to its initial allometry, suggesting that adjustments in biomass allocation made by other, larger seedling types must have come at the cost of lower growth. In contrast, adjustments in allocation did not appear to negatively impact pine, possibly because reduced root:shoot ratios of larger seedlings did not reduce NSC storage, as it did in aspen. Our results highlight (1) the complexity of how differences in biomass allocation and changes in seedling size may alter storage and the response of species to drought, and (2) the importance of accounting for initial seedling characteristics (both morphological and physiological) when predicting seedling growth and the impacts of environmental stressors.

The morphophysiological mechanisms of light-induced net primary production of Amazonian tree species

We investigated the morphophysiological mechanisms indicative of resource uses behind net primary production in seedlings of three valuable forest species of socio-economic value in the Amazon:mahogany (Swietenia macrophylla), Brazil nut (Bertholletia excelsa) and Laurel (Cordia alliodora). The hypotheses tested were: (i) the three species will grow better under mild to high light but with different magnitudes of response; and (ii) the three species will show different mechanisms to reach a better growth under mild to high light We measured biomass production and a set of morphophysiological leaf traits and calculated the relative growth rates (diameter and height) of seedlings subjected to low(0.9), moderate (11.3) and high (45.0 mol m-2 day-1) irradiance for 80 days. For all species, biomass and growth increase with irradiance and the magnitude of the effect were species-dependent. The changes in total biomass by irradiance varied 1.5-fold (B. excelsa) and twofold (S. macrophylla). Light-induced changes in biomass partitioning and morphophysiological traits varied among species. S. macrophylla and C. alliodora significantly increased root/aboveground mass ratio (R/A) under high irradiance. Gas exchange increased with irradiance for C. alliodora and B. excelsa. The non-structural carbohydrates of C. alliodora and S. macrophylla were greater in high (total soluble sugars) and moderate (starch) light environments. The traits associated with total biomass were starch, stomatal conductance and transpiration for B. excelsa; leaf area ratio, leaf area root mass ratio, total soluble sugars and starch for C. alliodora; and RIA, leaf area ratio, and leaf area root mass ratio for S. macrophylla. The species obtained a high total biomass under mild to high irradiance but following different morphophysiological mechanisms. We discussed the potential to use these mechanisms in silvicultural systems designed to supply the plants with intermediate to high levels of light, for example enrichment planting in secondary forests or reforestation on degraded areas.