Reproductive Biomass Research Articles

Arbuscular mycorrhizal fungus activates wheat physiology for higher reproductive allocation under drought stress in primitive and modern wheat

Arbuscular mycorrhizal fungus (AMF) can mediate physiological adaptation of higher plants to drought stress, including wheat. Yet, it is unclear how AMF affects reproductive output via mediating crop physiological vitality at the evolutionary scale. To clarify this issue, a growth environment-controlled experiment was conducted using four primitive wheat genotypes and four modern ones with or without AMF (Funneliformis mosseae) inoculation. Two water regimes (80 % and 40 % field water capacity, FWC80 (well-watered) and FWC40 (drought stress)) were included. The data indicated that AMF inoculation significantly improved leaf area, photosynthetic rate, stomatal conductance and water use efficiency under drought stress, compared to the non-AMF group (CK). Regardless of soil moisture, the relationship between reproductive biomass vs. vegetative biomass (R-V), and between leaf biomass vs. shoot biomass, all fell into a typical allometric pattern (α>1, P<0.001) in primitive wheat. In contrast, in modern wheat, the R-V relationship tended to an isometric pattern (α≈1, P<0.001), showing lower α values in all treatments relative to primitive ones. Furthermore, AMF inoculation significantly promoted the maintenance rate of yield and biomass under drought stress, suggesting greater drought tolerance as induced by AMF in modern wheat compared to primitive ones. These findings illuminated a key evolutionary strategy to enhance reproductive allocation via activating physiological activities under drought stress from primitive to modern wheat.

Role of plant functional traits in the invasion success: analysis of nine species of Asteraceae

Various attributes are hypothesized to facilitate the dominance of an invasive species in non-native geographical and ecological regimes. To explore the characteristic invasive attributes of the family Asteraceae, a comparative study was conducted among nine species of this family, co-occurring in the western Himalayan region. Based on their nativity and invasion status, the species were categorized as “Invasive”, “Naturalized”, and “Native”. Fifteen plant functional traits, strongly linked with invasion, were examined in the test species. The analyses revealed a strong dissimilarity between all the plant functional traits (except leaf carbon [Leaf C]) represented by “Invasive” and “Native” categories and most of the traits (except leaf area [LA], leaf nitrogen [Leaf N], Leaf C, and leaf carbon-nitrogen ratio [C: N]) represented by the “Naturalized” and “Native” categories. Similarly, “Invasive” and “Naturalized” categories also varied significantly for most of the traits (except Leaf N, Leaf C, capitula per m² population [Cm²], seeds per capitula [Scapitula], and seed mass). Invasive species are characterized by high LA, specific leaf area [SLA] and germination, and low C:N and leaf construction costs [LCC]. Most of the traits represented by native species justify their non-invasive behavior; whereas the naturalized species, despite having better size metrics (plant height), resource investment strategy (aboveground non-reproductive biomass [BNR], and aboveground reproductive biomass [BR]), and reproductive output (capitula per individual plant [Cplant], and seeds per individual plant [Splant]) failed to invade, which implies that the role of these functional aspects in imparting invasion potential to a species is not consistent in all the ecosystems and/or phylogenetic groups. Results of PCA revealed that trait divergence plays a more imperative role in invasion success than naturalization in the species of the family Asteraceae. The present study is intended to refine the pre-generalized invasion concepts associated with family Asteraceae to ensure more accurate identification of the potential invaders and better management of the existing ones.

Alpine grassland community productivity and diversity differences influence significantly plant sexual reproduction strategies.

Whether and how community structure variation affects plant sexual reproduction is crucial for understanding species' local adaptation and plant community assembly, but remains unrevealed. In Qinghai-Tibetan grassland communities that differed in aboveground biomass (AGB) and species diversity, we found significant influence of AGB on both species' reproductive biomass allocation (RBA) and flowering and fruiting time, but of species diversity only on species' reproductive time. In high-AGB or high-diversity communities, smaller and earlier flowering species generally advanced their reproductive phenology and increased their reproductive allocation for maximizing their reproductive success, whereas larger and later flowering species delayed their reproductive phenology and decreased their reproductive allocation for maximizing their vegetative growth and resource competition. This change in reproductive allocation with the variation in community structures was more pronounced in nonclonal as compared to clonal plant species. Thus, we evidence an important influence of community structure on plant sexual reproduction strategies, and the pattern of the influence depends largely on species biological attributes.

Effects of different sowing dates on biomass allocation of various organs and allometric growth of Fagopyrum esculentum.

The sowing date plays a crucial role in influencing the growth and reproduction of plants, with its specific impact on biomass allocation and allometric growth remaining unclear. Understanding these effects is essential for optimizing agricultural practices and enhancing crop productivity. To investigate the effects of sowing dates on biomass allocation and allometric growth, a field experiment was conducted with sequential sowings of Fagopyrum esculentum from April 12th to August 11th in 2018. Biomass measurements were taken across various plant organs, and corresponding allocation calculations were made. A detailed analysis of the allometric growth relationship involving organ biomass variations was performed. The study revealed that the accumulation and allocation of organ biomass in buckwheat were significantly impacted by the sowing dates. Delayed planting led to reduced vegetative growth and increased biomass allocation towards reproduction. Allometric parameters such as exponent, constant, and individual size of buckwheat were notably affected by delayed planting. Interestingly, the allometric exponents governing the relationships between reproductive vs. vegetative biomass and belowground vs. aboveground biomass exhibited varying trends across different sowing dates. Notably, late sowings resulted in significantly higher reproductive biomass compared to early and middle sowings. These findings highlight the nuanced relationship between plant size and reproductive biomass under different sowing dates, emphasizing the critical role of planting timing in shaping mature plant sizes and reproductive outcomes. The study underscores the importance of considering sowing dates in agricultural practices to optimize plant growth and productivity.

Effects of native species richness on reproduction of invasive Bidens pilosa vary with nutrient supply

BackgroundBoth increasing native species diversity and reducing nutrient availability can increase the ability of native plant communities to resist alien plant invasions. Furthermore, native species diversity and nutrient availability may interact to influence alien plant invasions. So far, however, little is known about the interactive effect of species diversity and nutrient availability on reproduction of alien invasive plants. We constructed native plant communities with one, four or eight species under low and high nutrient supply and then let them be invaded by the invasive alien plant Bidens pilosa.ResultsAt both high and low nutrient supply, increasing native species richness significantly increased aboveground biomass of the native plant community and decreased aboveground biomass and biomass proportion of the invader B. pilosa. Reproductive biomass of B. pilosa decreased significantly with increasing native species richness under high nutrient supply, but this effect was not observed under low nutrient supply. Net biodiversity effect on seed mass of B. pilosa decreased significantly with increasing native species diversity under high nutrient supply, but not under low nutrient supply. This was mainly because the selection effect became dominant with increasing species richness under high nutrient supply.ConclusionsOur study suggest that native species richness and nutrient supply can interact to influence reproduction of invasive alien plant species and that measures to help maintain a high level of native species richness and to reduce nutrient supply could be useful for efficient invasive plant control.

Improving nitrogen content in the carboxylation and electron transfer component can boost the reproductive biomass of filmless cotton in arid areas

AbstractDeep drip irrigation combined with high‐density planting is one of the most economical and effective ways to address residual film pollution. This study aimed to explore the photosynthetic potential of and achieve water‐saving and high‐yielding filmless cotton (Gossypium hirsutum L.) by optimizing the irrigation amount. We analyzed the effect of source leaf activity on leaf nitrogen allocation and photosynthetic nitrogen utilization efficiency (PNUE) under different irrigation amounts (mm, 375 (W5), 348 (W4), 320 (W3), 293 (W2), and 265 (W1)) in a 2‐year field experiment under this planting mode. The photosynthetic pigment content, leaf mass per area, and light compensation point all decreased with increasing amounts of irrigation, while the apparent quantum yield of photosynthesis, light saturation point, maximum carboxylation rate (Vcmax), maximum electron transport rate (Jmax), triose phosphate utilization rate (VTPU), nitrogen content in the electron transfer component (NB), and nitrogen content in the carboxylation component (NC) showed opposite trends. At the later full boll stage, the W3 and W4 treatments increased the leaf area of a whole plant (LA) by 10.4% and 19.4%, respectively, compared to that in the W1 treatment, while the PNUE increased by 20.2% and 20.8%, respectively, compared to that in the W5 treatment. In addition, principal component analysis found that the factor variables total nitrogen content in the photosynthetic apparatus (NT), net photosynthetic rate (Pn), stomatal conductance (Gs), light‐saturated net photosynthetic rate (Amax), NC, and Vcmax had higher loadings and were all positively correlated with PNUE; LA had a higher loading and was positively correlated with reproductive organ biomass. Therefore, we recommend using an irrigation rate of 320 mm in this cultivation system to increase nitrogen in carboxylation and electron transport components, enhance photosynthetic capacity, and thereby improve PNUE to increase reproductive organ biomass and reduce the irrigation amount in arid areas.

Non-stressful temperature changes affect transgenerational phenotypic plasticity across the life cycle of Arabidopsis thaliana plants.

Plants respond in a plastic manner to seasonal changes, often resulting in adaptation to environmental variation. Although much is known about how seasonality regulates developmental transitions within generations, transgenerational effects of non-stressful environmental changes are only beginning to be unveiled. This study aimed to evaluate the effects of ambient temperature changes on the expression of transgenerational plasticity in key developmental traits of Arabidopsis thaliana plants. We grew Columbia-0 plants in two contrasting temperature environments (18 and 24 °C) during their whole life cycles, or the combination of those temperatures before and after bolting (18-24 and 24-18 °C) across two generations. We recorded seed germination, flowering time and reproductive biomass production for the second generation, and seed size of the third generation. The environment during the whole life cycle of the first generation of plants, even that experienced before flowering, influenced the germination response and flowering time of the second generation. These effects showed opposing directions in a pattern dependent on the life stage experiencing the cue in the first generation. In contrast, the production of reproductive biomass depended on the immediate environment of the progeny generation. Finally, the seed area of the third generation was influenced positively by correlated environments across generations. Our results suggest that non-stressful environmental changes affect the expression of key developmental traits across generations, although those changes can have contrasting effects depending on the parental and grandparental life stage that perceives the cue. Thus, transgenerational effects in response to non-stressful cues might influence the expression of life-history traits and potential adaptation of future generations.

Subsurface irrigation with ceramic emitters improves greenhouse tomato yield and resource utilization efficiency by stabilizing soil hydrothermal status

Maintaining a stable and suitable soil hydrothermal status is crucial for promoting the high quality and yield of greenhouse vegetables throughout the year. Irrigation by regulating soil moisture changes to soil heat capacity is an effective measure to alleviate the fluctuation of soil hydrothermal environment caused by interannual solar radiation. To investigate the soil hydrothermal status of greenhouse tomatoes under subsurface irrigation with ceramic emitters (SICE) and its impact on tomato growth and yield, we conducted a two-season greenhouse experiment with subsurface drip irrigation (SDI) as a control. The results showed that soil hydrothermal changes under SICE fluctuated less with time in the autumn and spring experiment than SDI; SICE could increase soil temperature in the tomato root zone profile in winter and decrease the profile temperature in summer. This indicates that SICE could reduce the direct effect of air temperature on soil temperature and maintain a stable and suitable soil hydrothermal condition. Furthermore, the underground and vegetative biomass of SICE stopped increasing with the rapid growth of water and heat resources to the inflection point. They shifted to the accumulation of reproductive biomass. However, the vegetative biomass of SDI continued to increase in the late stage of water and heat resources. Therefore, under similar total biomass conditions, SICE obtained more output. SICE increased tomato yields by 11.60 in autumn and 8.36 t hm−2 in spring compared to SDI. The regulation mechanism also improved the hydrothermal resource utilization efficiency under SICE, with SICE increasing water and heat resource use efficiency by 24.04 % and 3.73 % (in autumn) and 9.80 % and 6.00 % (in spring), respectively, compared to SDI. We conclude that SICE is an effective and promising irrigation method for greenhouse tomato cultivation for stabilizing the soil water and heat environment, promoting yield, and improving the utilization rate of solar radiation.

Time to Onset of Flowering, Water Use, and Yield in Wheat

Crop breeding has been successful in increasing crop grain yield (GY; reproductive biomass) largely through reduced vegetative size, increased reproductive effort (RE = reproductive biomass/total biomass) and increased water-use efficiency (WUE) in grain production. Flowering time is an important life history trait that signifies the switch from vegetative to reproductive growth. The relationship between GY and time from sowing to flowering (Tsf) is unclear. We fit the relationships between GY and RE vs. Tsf to the logistic model using data from 18 spring wheat genotypes grown under simulated rainfed conditions. Tsf accounted for water use before and after flowering, root length density, total leaf area, and the time from flowering to harvest. Early flowering meant decreased water use before flowering and increased water use afterward. Soil water remaining at harvest was positively correlated with yield. Early flowering genotypes have a higher WUE of grain production, but there was no significant difference in the WUE of total biomass production. The relationship between grain yield and Tsf is described as a unimodal curve, as is the relationship between RE and Tsf. Higher yields and a higher RE have been achieved through earlier flowering, and both RE and Tsf reached their optimal values for maximizing GY. Crop breeding is unlikely to achieve further increases in GY through this route in the future. The results suggest that breeding does not improve biomass’s water-use efficiency, but causes changes in biomass allocation strategy, and this could be a new direction for genetically improving grain yield.

Greater flowering and response to flooding inLythrum virgatumthanL. salicaria(purple loosestrife)

Newly introduced trait diversity can spur rapid evolution and facilitate local adaptation in the introduced plant Lythrum salicaria. The horticultural plant L. virgatum might further introduce meaningful trait variation by escaping into established L. salicaria populations or by hybridizing with L. salicaria. Although many experiments have focused on L. salicaria genotypes, relatively little is known about L. virgatum ecology. We used a greenhouse common garden to compare traits and flood response of L. salicaria and L. virgatum collected from two sources each in their native range. We tested the hypotheses that these two wetland taxa have comparable responses to flooding (inundation), and that flood tolerance correlated to higher fitness. Flooding produced stronger stress responses in L. virgatum. Compared to L. salicaria, L. virgatum shifted more aboveground allocation away from reproduction, decreased inflorescence biomass by 40% more, and produced 7% more stem aerenchymatous phellum, a specialized tissue that maintains aeration. Despite these more pronounced responses to flooding stress, L. virgatum had higher fitness (inflorescence biomass and reproductive allocation) than L. salicaria. Overall, L. virgatum differed from L. salicaria in functionally important ways. Lythrum virgatum persisted under flooding and produced more reproductive biomass than L. salicaria under both flooded and non-flooded conditions. However, inundation stressed L. virgatum more than L. salicaria. Lythrum virgatum is likely able to establish into the wetland habitats in which L. salicaria prevails but may possess broader habitat tolerances.

Organic Nitrogen Supplementation Increases Vegetative and Reproductive Biomass in a Versatile White Rot Fungus.

The Black Poplar Mushroom Cyclocybe aegerita (syn. Agrocybe aegerita) is a white-rot fungus that naturally fruits from woody substrates, including buried wood. It is known for its substrate versatility and is equipped with a respective carbohydrate-active enzyme repertoire being intermediate between typical white-rot fungi and plant litter decomposers. Given relative nitrogen scarcity in wood, mobilization of nitrogen from surrounding litter is known as a way to meet nitrogen requirements for cellular homeostasis and reproduction of wood decay fungi. However, the effect of added nitrogen on vegetative and reproductive biomass has not yet been studied in a uniform minimalistic laboratory setup. For C. aegerita, such a growth and fruiting setup has been developed. In the present study, this white-rot fungus has been grown with and without additional β-adenosine, an organic nitrogen source present in plant litter. Elevated β-adenosine levels increased aerial mycelium weight by 30% (1 × β-adenosine) and 55% (10 × β-adenosine), reproductive biomass by 75% (1 × β-adenosine) and by 100% (10 × β-adenosine), number of primordia by 127% (10 × β-adenosine) and accelerated primordium formation by 1.6 days (10 × β-adenosine), compared to the control treatment. These findings imply that C. aegerita invests additional organic nitrogen resources into direct vegetative and reproductive biomass build-up at the same time. Colonization of niches with accessory nitrogen sources, like buried wood, which is near the plant litter layer, may thus provide an evolutionary fitness advantage. Globally anthropogenically altered nitrogen dynamics may affect hyphal-driven processes as well as fruit body-driven food webs.

Mepiquat chloride application combined with high plant population density promotes carbon remobilization in the roots of upland cotton

Carbon reserves in cotton roots can be remobilized to support reproductive growth, thus potentially affecting cotton yield. However, the regulation of carbon remobilization in cotton roots and its relationship with cotton yield are still poorly understood. Plant population density (PPD) and mepiquat chloride (MC) have been hypothesized to affect the dynamics of nonstructural carbohydrate content and the resulting carbon remobilization in cotton roots through the regulation of carbohydrate metabolism enzyme activities. A mid-maturation cotton line 4003–6 was field-grown in 2019 and 2020. Three different levels of PPD (D1: 2.25 plants m−2, D2: 4.5 plants m−2, and D3: 6.75 plants m−2) and two levels of MC dosage (M0: 0 g hm−2, M1: 82.5 g hm−2) were combined to create six populations differing in terms of the source–sink relationship. The changes in the hexose, sucrose, and starch contents and the key carbon metabolic enzyme activities in cotton roots were examined during peak squaring (PS) to late boll opening (LB). The combination of the PPD of 6.75 plants m−2 and MC application (M1D3) exhibited the greatest cotton yield and reproductive biomass–to–leaf area ratio from peak flowering (PF) onwards. M1D3 presented the greatest total nonstructural carbohydrate (TNC) remobilization amount of 2.96 and 3.80 g m−2, the highest efficiency of 39.11% and 48.39%, and the largest gross contribution to seed cotton yield of 0.66% and 0.79% in 2019 and 2020, respectively. The three parameters were positively correlated with the seed cotton yield except for the remobilization rate in 2019. Unlike the other treatments, the greater carbohydrate content per unit ground area in M1D3 prior to the PF stage was attributed to the higher sucrose phosphate synthase (SPS) and ADP-glucose pyrophosphorylase (AGPase) activities during the PS to first flowering (FF) stages. Conversely, the greater α-amylase and β-amylase activities in M1D3 at the PF stage accounted for the lower starch content at the EB stage, and the smaller vacuolar invertase (VIN) and cell wall invertase (CWIN) activities at the EB stage could be responsible for the lower hexose concentration at that time. The TNC remobilization amount had a positive association with the AGPase and SPS activities at the FF stage and with β-amylase activity at the PF stage in cotton tap roots in 2019 and 2020. This study provides a cotton yield-improving alternative through the promotion of carbon remobilization in roots using certain agronomic practices.

Timing of a plant-herbivore interaction alters plant growth and reproduction.

Phenological shifts have the potential to change species interactions, but relatively few studies have used experimental manipulations to examine the effects of variation in timing of an interspecific interaction across a series of life stages of a species. Although previous experimental studies have examined the consequences of phenological timing in plant-herbivore interactions for both plants and their herbivores, less is known about their effects on subsequent plant reproduction. Here, we conducted an experiment to determine how shifts in the phenological timing of monarch (Danaus plexippus) larval herbivory affected milkweed (Asclepias fascicularis) host plant performance, including effects on growth and subsequent effects on flower and seed pod phenology and production. We found that variation in the timing of herbivory affected both plant growth and reproduction, with measurable effects several weeks to several months after herbivory ended. The timing of herbivory had qualitatively different effects on vegetative and reproductive biomass: early-season herbivory had the strongest effects on plant size, whereas late-season herbivory had the strongest effects on the production of viable seeds. These results show that phenological shifts in herbivory can have persistent and qualitatively different effects on different life stages across the season.

Allometric Characteristics of Rice Seedlings under Different Transplanted Hills and Row Spacing: Impacts on Nitrogen Use Efficiency and Yield.

The number of seedlings per hill and the configuration of plant row spacing are important management measures to improve rice yield. In the present study, we evaluated the impact of various seedlings per hill (1, 3, 6, and 9 seedlings hill−1) under four different rice verities (two conventional rice, two hybrid rice) on allometric characteristics, nitrogen use efficiency (NUE) and yield in 2020 at early and late season. Results showed that compared with nine seedlings per hill (wide row spacing), the number of effective panicles, yield, grain biomass allocation, grain-to-leaf ratio, grain nitrogen accumulation, nitrogen dry matter production efficiency (NDMPE), N harvest index (NHI) of 1 seedling per hill increased by 21.8%, 10.91%, 10.5%, 32.25%, 17.03%, 9.67%, 6.5%, respectively. With the increase of seedlings per hill and the expansion of row spacing, stem biomass (SB) and reproductive biomass (RB) increased with the increase of above-ground biomass, mainly showing the relationship of isometric growth. Leaf biomass (LB) increased with above-ground biomass, mainly showing the relationship of allometric growth. The results suggested that under the same basic seedlings, transplanting 1 seedling per hill and dense planting was the most beneficial to improve rice yield.

Effects of parental drought on offspring fitness vary among populations of a crop wild relative.

Transgenerational plasticity is a form of non-genetic inheritance that can reduce or enhance offspring fitness depending on parental stress. Yet, the adaptive value of such parental environmental effects and whether their expression varies among populations remain largely unknown. We used self-fertilized lines from climatically distinct populations of the crop wild relative Lupinus angustifolius. In the parental generation, full-siblings were grown in two contrasting watering environments. Then, to robustly separate the within-generation and transgenerational response to drought, we reciprocally assigned the offspring of parents to the same experimental treatments. We measured key functional traits and assessed lifetime reproductive fitness. Offspring of drought-stressed parents produced less reproductive biomass, but a similar number of lighter seeds, in dry soil compared to offspring of genetically identical, well-watered parents, an effect not mediated by differences in seed provisioning. Importantly, while the offspring of parents grown in the favourable environment responded to drought by slightly increasing individual seed mass, the pattern of plasticity of the offspring of drought-grown parents showed the opposite direction, and the negative effects of parental drought on seed mass were more pronounced in populations from cooler and moist habitats. Overall, our results show that parental effects may override immediate adaptive responses to drought and provide evidence of population-level variation in the expression of transgenerational plasticity.

Whole-vine resources modify within-vine relationships between growth parameters and metabolites in &lt;i&gt;Vitis vinifera&lt;/i&gt; L. cv. Cabernet-Sauvignon

Fruit ripening on a perennial tree or vine is typically asynchronous and rarely investigated. In commerce, this is problematic as it impairs sampling to meet commercial maturity and quality standards at harvest. For grapevines, understanding within-grapevine variability in berry maturity will benefit precision management and harvest planning. It is accepted that variation in maturity is approximately equally allocated at the within- and between-vine scale. However, the mechanistic and ecological factors that cause functional variance are poorly understood and rarely documented.This study aimed to identify structural and spatial within-vine attributes associated with berry composition at harvest related to available resources from the whole grapevine. Vegetative and reproductive biomass attributes within- and between-vines were analysed for cv. Cabernet-Sauvignon trained as a cordon, spur-pruned system using a Smart-Dyson trellis in a ‘New World’ industrial-scale vineyard. The vines were located in northern Margaret River, Western Australia. Variability in soluble solids, anthocyanins and phenolics were analysed for clusters and corresponding canopy characteristics.Berry size was the best predictor of variance in maturity among sugar, anthocyanins and phenolics composition within individual vines. Smaller stems or fruit had greater variation in maturity than larger stems or fruit. However, the relationship between whole plant biomass and fruit maturity interacted at different scales; the first report for grapevines. Including different vine-biomass scales helped explain the heteroscedasticity observed when the individual vine effect was excluded from the analysis. These findings suggest that high vigour grapevines could benefit from differential management, regardless of harvest index. Furthermore, these findings may help explain the diversity of response to treatment effects such as cluster or leaf thinning reported previously for perennial fruit.

Massive loss and microbial decomposition in reproductive biomass of Zosteramarina

The biomass of Zostera marina in the temperate coastal zone has seasonal variations in their dry weight, with a peak during the spring season when a large section of the shoots develops reproductive organs. However, the period of high biomass is only short-term, after which large numbers of reproductive shoots drastically disappeared. Dislodgement is an important fate of the reproductive biomass. The fraction of biomass that reaches the deep sea contributes to carbon sequestration, however the processes of dislodgement and transportation of reproductive shoots of Z. marina has been rarely studied. Here, based on a monitoring survey of two Z. marina meadows, we estimated the net loss of biomass, including their reproductive one. In addition, microbial decomposition was assessed by dark incubation to evaluate the fate of the dislodged biomass. The apparent loss of biomass from the Z. marina meadows in the “Declining Period”, defined with the most rapid decrease in biomass, accounted for 82–100% of the biomass at the initial time-point of this period. By subtracting the biomass production from the apparent loss, we calculated the net loss of biomass in the Declining Period, accounting for 14–81% of the annual production. Approximately half of the biomass loss in the Declining Period was attributed to reproductive biomass, suggesting that dislodgement of reproductive shoots is an important fate of photosynthetic products of Z. marina. The carbon to nitrogen (CN) ratio of the reproductive shoots was found to be significantly higher than that of vegetative shoots. Since nitrogenous materials are relatively labile, we expected a lower bioavailability of reproductive shoots. However, microbial decomposition did not reflect the CN ratio, probably due to the heterogeneity of nitrogenous materials and/or due to the contribution of carbohydrates consisting mostly of non-nitrogenous compounds.

Increased Coastal Nutrient Loading Enhances Reproductive Intensity of Zostera marina: Implications for Seagrass Meadow Resilience

Because sexual reproduction is essential for the establishment and persistence of seagrass meadows, flowering intensity is an important trait that influences the resilience and stability of seagrass populations. Although the effects of excessive coastal nutrient loading on seagrass vegetative growth have been extensively documented, the effects on seagrass reproductive phenology and intensity remain unclear. To examine the reproductive responses of seagrass populations to increased coastal nutrient loading, the flowering phenology and intensity of Zostera marina were compared between sites with high-nutrient, low-light conditions (Deukryang Bay and Dongdae Bay) and low-nutrient, high-light conditions (Koje Bay) on the southern coast of Korea. Nutrient contents of the above- and below-ground tissues of Z. marina reflected in situ nutrient and light availability at the study sites. Reproductive shoot density and biomass, as well as flowering frequency and reproductive effort, were much higher (1.5–4.6-fold) at the high-nutrient, low-light study sites of Deukryang Bay and Dongdae Bay than at the low-nutrient, high-light site of Koje Bay. Consequently, potential seed production was higher in Deukryang Bay and Dongdae Bay than in Koje Bay. Chronic high-nutrient and low-light conditions significantly increased the reproductive intensity of Z. marina, supporting the persistence and resilience of Z. marina populations. The results of this study could provide insights into the conservation and management of seagrass meadows under increased coastal nutrient loading.

Phenology and Population Differentiation in Reproductive Plasticity in Feathertop Rhodes Grass (Chloris virgata Sw.)

An understanding of phenology and reproductive plasticity of a weed species can provide valuable information to manage it precisely. This study evaluated the phenotypic plasticity of feathertop Rhodes grass (Chloris virgata Sw.) where cohorts of four different populations (two from cropping and two from roadside situations) were initiated in early spring (4 September), late spring (4 November), mid-summer (4 January), and early autumn (4 March) in southern New South Wales (NSW), Australia. The team grew individual plants in the absence of competition under natural conditions. Life-history and fitness-related traits of both phenology and morphology were measured, and dry biomass of vegetative and reproductive parts were determined at physiological maturity. Among the four sowing times, the late-spring sowing treatment took the longest time from emergence to the first seed head emergence (70–110 days), while it had the shortest seed maturity period (8–16 days). Length of reproductive and total life period of the four populations differed across the four sowing-time treatments. The plants that emerged in mid-summer had the longest reproductive period (30 days) whereas the early-autumn emerging plants died before the reproductive stage because of the cold temperatures during winter. The mid-summer cohort required slightly longer time (63–85 days) to achieve seed head formation and less time (19–24 days) for seed maturity than those plants that emerged in early or late spring. All the reproductive features were varied by sowing times and population. The number of seed heads (12–15 per plant) and spikelets (12–13 per seed head), as well as the seed head biomass, re-productive biomass allocation pattern, and seed production, generally increased in the mid-summer-emerged cohort. Seed production in the mid-summer (9942 seeds/plant) cohort was 10% and 70% higher than the late spring (8000 seeds/plant) and early spring (3240 seeds/plant) cohorts, respectively. The ratio of reproductive biomass to vegetative biomass increased in the mid-summer sowing times in all populations, and this species displayed true plasticity in reproductive allocation. Additionally, the four populations of feathertop Rhodes grass differed significantly in phenological, vegetative, and reproductive traits, depending on the sowing time. The reproductive fitness of the four populations varied, with the two roadside populations (FELT 04/20 and STURT/16–17) appearing to be better adapted than the two cropping populations (PARK 01/20 and GLEN 03/18). The results from our study could help construct a basic framework for a variety of weed-management tactics to achieve successful control.

The dynamics of carbohydrate and associated gene expression in the stems and roots of upland cotton (Gossypiumhirsutum L.) during carbon remobilization

Carbohydrates remobilization in non-leaf organs has a potential association with the formation of cotton yield. However, our understanding of the physiological and molecular mechanisms regulating carbon remobilization during flowering is still limited. The objectives of the study were to: i) evaluate the potential of carbohydrate remobilization in stems and roots to yield formation; ii) unravel the carbon metabolism and transport associated gene expression patterns regulating carbon remobilization. Two cotton lines 4003-6 and 4003-10 were employed to examine leaf photosynthesis, reproductive biomass accumulation, and carbon dynamics in stems and roots during reproductive growth. The results showed that decreasing leaf photosynthetic capacity combined with rapidly increasing reproductive biomass and leaf area index is accompanied by the initiation of carbohydrate remobilization during first flowering to peak flowering. The proportion of sucrose to total nonstructural carbohydrate was also decreased at that period. The upper and lower of stem recorded higher soluble sugars and starch concentrations, respectively compared to the two others. The gross contribution rate of carbon remobilization to seed cotton yield ranged from 2.83% to 7.12%. Key genes and sugar transporters related to starch and sucrose metabolism in the lower stem exhibited significant up- or down-regulated expressions indicating their important roles in carbon reserves remobilization. Three pivotal sugar transporters SWEET1, TMT2, and ERLD5 presented higher transcript levels at peak flowering suggesting more active sugar movement occurring at that stage. The present study provides potential target genes for engineering carbohydrate metabolism and transport to improve the remobilization efficiency of nonstructural carbohydrates.