Biomass Partitioning Research Articles

Biometric Parameters and Yield Components of Wheat (Triticum aestivum) as a Function of Lime and Phosphogypsum Reapplication

ABSTRACT The effects of lime and phosphogypsum (GY) on wheat (Triticum aestivum) nutrition are well documented. However, little is known about the influence of these soil amendments on biometric parameters or yield components. This study investigated the effects of lime and GY on wheat crops grown at cation base saturation (BS) levels of 44%, 70%, and 90%, achieved by surface application or soil incorporation of lime. Two additional treatments were included: surface liming to 70% combined with a standard rate of GY (3.71 Mg ha−1) or twice the recommended GY rate (7.42 Mg ha−1). The experiment was conducted during two crop seasons in Southern Brazil. The treatments did not influence dry biomass partitioning between spikes, stems, and leaves and total. In one season, liming increased flag leaf area, which was strongly associated with grain yield. Regardless of the rate, application method, and combined use of GY, liming increased the number of grains per spike in both seasons, which was the variable that most influenced wheat yield. Liming also increased spike length and the number of spikelets per spike in the 2018 season. No benefits were seen when lime was applied by soil incorporation, BS was raised to 90%, or liming was combined with GY application. The results showed a positive effect of liming on wheat yield components that are associated with grain yield.

Drought tolerance to overwatering, periodic underwatering and complete withholding of water in interior Douglas-fir seedlings

Seedlings of 95 greenhouse-grown interior Douglas-fir half-sibling families originating from four breeding zones were subject to overwatering and periodic underwatering and compared to an optimally watered control (15 per family = 1425 seedlings total). Averaged over all trees, annual height was reduced by 4% and 11% compared to controls for overwatering and periodic underwatering, respectively. Family overwatered seedling height was 135–75%, and underwatered height was 100–75% of their respective control heights. Shorter families under stress grew like their control compared to taller families, but this was reversed in taller families when the watering conditions were ideal. A survival analysis indicated that after 30–50 days without water, family survival varied from 25% to 90%, and most trees died after 60 days. The breeding zone had little effect on the tolerance to suboptimal water or survival during complete water withdrawal and did not interact with watering treatments. Family traits for tolerance to overwatering favoured root biomass, traits for underwatering favoured reduced stem biomass, especially in ratio to roots, and traits for survival favoured belowground biomass over aboveground biomass. No tradeoffs between tolerance to over- and underwatering were found. Some families did well in all three conditions and some in one or the other. The study results suggest that variation in family growth and survival to suboptimal watering partly relate to root and stem biomass partitioning in the interior Douglas-fir population of British Columbia.

Effect of nitrogen fertilizer on growth, yield and quality parameters of three sugarcane (<em>Saccharum Officinarum</em> L.) varieties

This study examines the effects of nitrogen on the growth, yield and quality of three sugarcane varieties under irrigated conditions in the low country dry zone of Sri Lanka. Three sugarcane varieties (SL96-128, SL04-624 and SL8306) were tested at four nitrogen fertilizer levels (0, 100, 200, 300 kg/ha) in a split plot design with four replicates. Selected growth, yield and quality parameters were studied in this field experiment. The results of the study demonstrated that application of 100kg/ha or 300kg/ha N fertilizer has shown highest girth of stem (cm), partitioning biomass to millable stalk (PBMS), brix and pol percentage in all three varieties, SL04-624, SL8306 and SL96-128. In addition, variety SL04-624 have shown highest total above ground biomass production (dry matter) (41987.8kg/ha), partitioning biomass to millable stalk (PBMS) (74.5%), brix (19.4%), pol (17.1%) and pure obtainable cane sugar (POCS) (12.3%). Therefore 100k/ha (N2) could be concluded as the best rate of N fertilizer application for the varieties tested in this study considering the cost of production, environmental and groundwater pollution. SL04-624 could be recommended as the most suitable variety for low country wet zone of Sri Lanka responding to 100kg/ha N fertilizer.

Cultivation Strategies to Modify Biomass Partitioning and Improve Yield in Controlled-environment Production of High-cannabidiol Cannabis (Cannabis sativa L.)

Two common challenges reported by cannabis growers are low yields and small profit margins. Although recent research of cannabis yield has focused on lighting and nutrition, little research has examined how changes in other cultivation practices may be beneficial. The objective of this study was to evaluate the following two techniques to potentially improve yield: fertilizer restriction (FR) to reduce plant size and, thus, increase plant density and shoot number manipulation (SNM) to reduce shoot length and improve biomass partitioning. The FR technique involves leaching the substrate and providing only tap water for 0, 1, or 2 weeks at the start of flower initiation, whereas SNM involves pinching shoot tips 2, 3, or 4 times to produce 4, 8, or 16 shoots/plant, respectively. This study used a full factorial treatment design for a total of nine treatments (three FR × three SNM). Plants were flowered under 12-hour photoperiods for 8 weeks and then destructively harvested for data collection. The results demonstrated that both techniques improve plant productivity in different ways. The FR technique reduced all mass measurements (g/plant) and decreased plant area (m2/plant); therefore, the yield metrics (kg·m−2) increased with the increasing FR treatments. The SNM technique did not affect plant area, but more pinching events resulted in a decrease in reproductive shoot length (cm/shoot) and an increase in inflorescence to trim the dry mass ratio (inflorescence:trim). Shorter shoot lengths are desirable for eliminating trellis support netting, which helps growers reduce material costs and improve labor efficiency during harvest. Increasing the inflorescence:trim may also reduce labor costs related to trimming, which comprise the largest cost of production by many growers. Although both techniques offer advantages, there are trade-offs that must be considered in the context of overall profitability.

Cultivating resilience: use of water deficit to prime peanut production and improve water stress tolerance

Regulated deficit irrigation is a potential strategy for priming peanut plants to improve their acclimation to water stress. To assess possible effects of priming and develop an effective water stress priming strategy, greenhouse experiments were conducted to compare primed and non-primed peanut cultivars, C7616 and TUFRunner ‘511’TM, to subsequent water stress. Plants were divided into 1) controls with daily irrigation to field capacity throughout the entire growth cycle, 2) non-primed plants receiving daily irrigation up to 55 to 65 days after planting (DAP), followed by exposure to mid-season water stress, and 3) primed plants that received 50% of the control irrigation either from 5-45 DAP (long-term priming), or 20-45 DAP (short-term priming), followed by mid-season water stress at 55 to 65 DAP. An automated physiological phenotyping platform was used to control irrigation and continuously monitor, soil water content, whole-plant transpiration and water use. Single-leaf measurements of net CO2 assimilation, stomatal conductance, and transpiration were taken periodically. Plant biomass and biomass partitioning were also determined. Results indicated that primed plants grown under water deficit exhibited either reduced (acclimated) or intensified (sensitized) physiological stress responses upon recurrent water stress. Timing and duration of the priming period played a key role in modulating plant phenotypic plasticity, which varied by genotype, suggesting that priming could be in part genetically controlled.

The root strategy of the C4 grasses tends to be ‘do-it-yourself’

Root resource acquisition strategies play a crucial role in understanding plant water uptake and drought adaptation. However, the interrelationships among mycorrhizal associations, root hair development, and fine root strategies, as well as the disparities between C3 and C4 grasses, remain largely unknown. A pot experiment was conducted to determine leaf gas exchange, root morphology, root hair, mycorrhizal fungi, and biomass allocation of three C4 grasses and four C3 grasses, common species of grasslands in Northeast China, under the control and drought conditions. Compared to the C3 grasses, the C4 grasses increased specific surface area by decreasing tissue density, yet exhibited root hair factor at only 21 % of the C3 grasses. Under the drought conditions, the C4 grasses exhibited more intense and extensive adjustments in root traits, characterized by shifts toward a more conservative morphology with increased root diameter and tissue density, as well as reduced mycorrhizal colonization rates. These adaptations led to a decrease in root absorptive function, which was compensated in the C4 grasses by greater root biomass partitioning and root hair factor. Variances in root strategies between plants functional groups were closely related to leaf photosynthetic rate, water and nitrogen use efficiency. We observed that the C4 grasses prefer direct acquisition of soil resources through the fine root pathway over the root hair or mycorrhizal pathway, suggesting a ‘do-it-yourself’ approach. These findings provide valuable insights into how plant communities of different photosynthetic types might respond to future climate change.

Branching response to stem density and its impact on yield in hybrid potato grown from true seeds and seedling tubers

ContextHybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood. ObjectivesWe quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production. MethodsTwo field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance. ResultsOn individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect. ConclusionOur results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production.

Effects of crop forcing and water availability on yield and biomass partitioning in Tempranillo vines

Effects of crop forcing and water availability on yield and biomass partitioning in Tempranillo vines

Enhanced root system architecture in oilseed rape transformed with Rhizobium rhizogenes

Transformation of plants using wild strains of agrobacteria is termed natural transformation and is not covered by GMO legislation in e.g. European Union and Japan. In the current study, offspring lines (A11 and B3) of Rhizobium rhizogenes naturally transformed oilseed rape (Brassica napus) were randomly selected to characterize the morphological traits, and analyze the implications of such morphological changes on plant drought resilience. It was found that the introduction of Ri-genes altered the biomass partitioning to above- and under-ground parts of oilseed rape plants. Compared to the wild type (WT), the A11 and B3 lines exhibited 1.2–4.0 folds lower leaf and stem dry weight, leaf area and plant height, but had 1.3–5.8 folds greater root dry weight, root length and root surface area, resulting in a significantly enhanced root: shoot dry mass ratio and root surface area: leaf area ratio. In addition, the introduction of Ri-genes conferred reduced stomatal pore aperture and increased stomatal density in the B3 line, and increased leaf thickness in A11 line, which could benefit plant drought resilience. Finally, the modulations in morphological traits as a consequence of transformation with Ri-genes are discussed concerning resilience in water-limited conditions. These findings reveal the potential of natural transformation with R. rhizogenes for drought-targeted breeding in crops.

Rice Response to Spermine Foliar Application and Its Association with Aerial Imagery Monitoring Under Water Stress Conditions

Rice is the most consumed food in the world, mainly in Asia and Africa. Malaysia is the second-largest rice importer in Southeast Asia after Indonesia. However, rice yield is limited by water stress. One alternative for a quicker strategy to mitigate water stress is through a combination of foliar spermine application and efficient rice management practices via image monitoring techniques using drone technology. The present study was aimed at evaluating the effects of spermine on rice physiological response and its association with aerial imagery and yield under reproductive during reproductive stage under water stress. The experiment was carried out under greenhouse conditions using a two-factorial randomized complete block design (RCBD), with foliar spermine treatment as the first factor and water stress as the second factor. Physiological parameters showed significantly higher tiller number per pot and photosynthesis rate by 29% and 31%, respectively. Correspondingly, the Normalised Difference Vegetation Index (NDVI) using aerial imagery monitoring showed an increased value in spermine treatments by 2% compared to control. Furthermore, NDVI readings and photosynthetic rate were positively correlated linearly with R2= 0.51. Interestingly, spermine treatments alleviated water stress effects by 40%, 17% and 12% in grain weight per pot, grain number per panicle and percentage filled grain. Biomass partitioning in roots improved by 44% in spermine treatments, even under water stress, due to an efficient translocation of assimilates. In conclusion, spermine foliar application significantly improved growth, grain filling and rice yield production, which was also supported by NDVI values using aerial imagery monitoring.

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The production of drought-tolerant rice varieties in Malaysia and the information regarding the response of local varieties to water stress are still lacking. Therefore, this experiment was conducted to determine the growth, physiological performance, molecular response, and yield of ten available rice varieties, namely MR 219, MR 220-CL2, MR 297, MRQ 76, Vietnam Hybrid, UKM RC2, UKM RC8, Putra 1, MR 303, and MR 307, under ten days of cyclic water stress. The experiment was arranged in a Randomized Complete Block Design (RCBD) with three replications. Plant height, tiller number, photosynthesis rate, stomatal conductance, transpiration rate, chlorophyll content, biomass partitioning, genotyping of SSR markers, days of harvest, and yield component were measured. Results showed that water limitations reduced tiller number per hill, while plant height, leaf dry matter, and panicle length were enhanced. It was found that MR 297 had the shortest plant height, while MR 220-CL2 had a short maturity period, a shorter panicle length, and an enhanced filled grain percentage. Putra 1 and UKM RC8 showed a higher photosynthesis rate, stomatal conductance, and transpiration rate under water limitation at 99 days after sowing (DAS). Under well-watered conditions, the total grain weight per pot of Putra 1 and MR 307 was enhanced compared to MR 219. Meanwhile, under water limitation, the total grain weight per pot of UKM RC2, MR 220-CL2, MR 307, MR 297, and Vietnam Hybrid was comparable to MR 219 and slightly enhanced in UKM RC8, Putra 1, and MR 303. Among the tested varieties, MR 220-CL2 can be selected based on early maturity criteria for the potential development of drought-tolerant varieties.

Growth and Biomass Distribution in Cocoa Varieties under Different Nitrogen Regimes

Among the 17 vital plant nutrients, nitrogen (N) is crucial in crop production. It extensively enhances the growth and biomass production of plants by improving photosynthesis and protein synthesis. To study the impact of three different N levels (40, 80, and 120 ppm) on the growth and biomass production of eight cocoa varieties, a hydroponic experiment was carried out at ICAR-CPCRI, Regional Station, Vittal. The results showed that increasing N concentration significantly boosted growth and biomass production. Among the different varieties, VTLCH-1 exhibited the highest plant height, maximum number of leaves, greater stem diameter, and the highest total fresh biomass with the application of 120 ppm nitrogen. Biomass partitioning analysis revealed that higher N levels increased leaf and stem biomass while reducing root biomass, leading to a higher shoot-to-root ratio. This indicates that N application influences the biomass production and distribution in the plant.

Effects of Drought Stress on Leaf Functional Traits and Biomass Characteristics of Atriplex canescens.

Drought is a critical factor constraining plant growth in arid regions. However, the performance and adaptive mechanism of Atriplex canescens (A. canescens) under drought stress remain unclear. Hence, a three-year experiment with three drought gradients was performed in a common garden, and the leaf functional traits, biomass and biomass partitioning patterns of A. canescens were investigated. The results showed that drought stress had significant effects on A. canescens leaf functional traits. A. canescens maintained the content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD), but the peroxidase (POD) and catalase (CAT) activity decreased, and the content of proline (Pro) and soluble sugar (SS) increased only under heavy drought stress. Under drought stress, the leaves became smaller but denser, the specific leaf area (SLA) decreased, but the dry matter content (LDMC) maintained stability. Total biomass decreased 60% to 1758 g under heavy drought stress and the seed and leaf biomass was only 10% and 20% of non-stress group, but there had no significant difference on root biomass. More biomass was allocated to root under drought stress. The root biomass allocation ratio was doubled from 9.62% to 19.81% under heavy drought, and the root/shoot ratio (R/S) increased from 0.11 to 0.25. The MDA was significantly and negatively correlated with biomass, while the SPAD was significantly and positively correlated with total and aboveground organs biomass. The POD, CAT, Pro and SS had significant correlations with root and seed allocation ratio. The leaf morphological traits related to leaf shape and weight had significant correlations with total and aboveground biomass and biomass allocation. Our study demonstrated that under drought stress, A. canescens made tradeoffs between growth potential and drought tolerance and evolved with a conservative strategy. These findings provide more information for an in-depth understanding of the adaption strategies of A. canescens to drought stress and provide potential guidance for planting and sustainable management of A. canescens in arid and semi-arid regions.

Optimal Planting Density Increases the Seed Yield by Improving Biomass Accumulation and Regulating the Canopy Structure in Rapeseed.

Planting density is an important factor affecting plant growth and yield formation in rapeseed. However, the understanding of the mechanism underlying the impact of planting density on biomass, canopy, and ultimate seed yield remains limited. A field experiment was conducted to investigate the effect of planting density on seed yield, yield components, biomass accumulation and partitioning, and canopy structure. Five planting density levels were set as D1 (2.4 × 105 plants ha-1), D2 (3.6 × 105 plants ha-1), D3 (5.4 × 105 plants ha-1), D4 (6.0 × 105 plants ha-1), and D5 (7.2 × 105 plants ha-1). The results showed that with planting density increasing from D1 to D3, the seed yield, number of pods in population, and 1000-seed weight increased, while seedling survival rate, yield per plant, number of pods per plant, and number of seeds per plant decreased. When planting density increased to D4 and D5, seed yield dramatically decreased due to a decreased number of seeds per pod and 1000-seed weight. Increasing planting density from D1 to D3 increased biomass accumulation in all organs. D3 produced the highest biomass partitioning in seeds. In addition, D2 and D3 treatments had a high level of pod area index (5.3-5.8), which caused an approximately 93% of the light to be intercepted. The distribution of light in D2 and D3 was more evenly spread, with the upper and lower parts of the canopy displaying a distribution ratio of roughly 7:3. Therefore, D2 and D3 produced the highest seed yields. In conclusion, D2 and D3 are recommended in rapeseed production due to their role in improving biomass accumulation and partitioning and canopy structure.

Elevational variation in morphology and biomass allocation in carpathian snowbell Soldanella carpatica (Primulaceae).

Plants growing along wide elevation gradients in mountains experience considerable variations in environmental factors that vary across elevations. The most pronounced elevational changes are in climate conditions with characteristic decrease in air temperature with an increase in elevation. Studying intraspecific elevational variations in plant morphological traits and biomass allocation gives opportunity to understand how plants adapted to steep environmental gradients that change with elevation and how they may respond to climate changes related to global warming. In this study, phenotypic variation of an alpine plant Soldanella carpatica Vierh. (Primulaceae) was investigated on 40 sites distributed continuously across a 1,480-m elevation gradient in the Tatra Mountains, Central Europe. Mixed-effects models, by which plant traits were fitted to elevation, revealed that on most part of the gradient total leaf mass, leaf size and scape height decreased gradually with an increase in elevation, whereas dry mass investment in roots and flowers as well as individual flower mass did not vary with elevation. Unexpectedly, in the uppermost part of the elevation gradient overall plant size, including both below-and aboveground plant parts, decreased rapidly causing abrupt plant miniaturization. Despite the plant miniaturization at the highest elevations, biomass partitioning traits changed gradually across the entire species elevation range, namely, the leaf mass fraction decreased continuously, whereas the flower mass fraction and the root:shoot ratio increased steadily from the lowest to the highest elevations. Observed variations in S. carpatica phenotypes are seen as structural adjustments to environmental changes across elevations that increase chances of plant survival and reproduction at different elevations. Moreover, results of the present study agreed with the observations that populations of species from the 'Soldanella' intrageneric group adapted to alpine and subnival zones still maintain typical 'Soldanella'-like appearance, despite considerable reduction in overall plant size.

Short-term responses of growth and leaf physiology of the sclerophyllous Cryptocarya alba (Molina) seed sources to water restriction

ABSTRACT There are concerns about the vulnerability of some dominant sclerophyllous species in Mediterranean zones to water restriction, especially at outplanting, and much of the efforts for active restoration are on identifying proper seed sources. This study aimed to determine the short-term responses of growth, biomass partitioning, and leaf-physiological traits of Cryptocarya alba provenances to water restriction in nursery conditions. Three seed sources from xeric sites (northern distribution) and one from a more mesic site (southern distribution) were subjected to water restriction for three months and then evaluated in increments in root collar diameter and height, biomass components (leaves, shoots, roots), gas-exchange and fluorescence parameters, and carbon (Δ13) and oxygen (δ18O) isotopic ratios. Water restriction decreased growth and leaf biomass as a short-term response, but this effect was not expressed in stem and root biomass. Similarly, water restriction decreased the photosynthetic rate (Asat), stomatal conductance (gs), and maximum efficiency of PSII. Moreover, water restriction also increased the intrinsic water use efficiency (WUEint), but it had no effect on Δ13 or δ18O. Seed sources did not differ in any traits except in stem and total biomass. The results did not confirm a better performance of seed sources from xeric than mesic origin sites to water restriction.

Effects of Wind Exposure and Deficit Irrigation on Vegetative Growth, Yield Components and Berry Composition of Malbec and Cabernet Sauvignon.

The impact of global warming on Argentine viticulture may result in a geographical shift, with wine-growing regions potentially moving towards the southwest, known as one of the windiest regions in the world. Deficit irrigation is a widely used strategy to control the shoot growth and improve fruit quality attributes, such as berry skin polyphenols. The present study aimed to assess the effects of different wind intensities and irrigation levels, as well as their interactions, on field-grown Vitis vinifera L. cvs. Malbec and Cabernet Sauvignon. The experiment was conducted during two growing seasons with two wind treatments (sheltered and exposed) and two irrigation treatments (well-watered and moderate deficit irrigation) in a multifactorial design. Vegetative growth, stomatal conductance, shoot biomass partition, fruit yield components and berry skin phenolics were evaluated. Our study found that, generally, wind exposure reduced vegetative growth, and deficit irrigation increased the proportion of smaller berries within the bunches. Meanwhile, deficit irrigation and wind exposure additively increased the concentration of berry skin phenolics. Combined stressful conditions enhance biomass partition across the shoot to fruits in Malbec, increasing the weight of bunches and the number of berries. Our findings offer practical implications for vineyard managers in windy regions, providing actionable insights to optimize grapevine cultivation and enhance wine quality.

Effects of Nitrate Assimilation in Leaves and Roots on Biomass Allocation and Drought Stress Responses in Poplar Seedlings

Knowledge of tree biomass allocation is fundamental for estimating forest acclimation and carbon stock for global changes in the future. Optimal partitioning theory (OPT) and allometric partitioning theory (APT) are two major patterns of biomass allocation, and occurrences have been tested on taxonomical, ontogenetic, geographic and environmental scales, showing conflicting results and unclear ecophysiological mechanisms. Here, we examine the biomass allocation patterns of two young poplar (Populus) clones varying greatly in drought resistance under different soil water and nitrogen availabilities and the major physiological processes involved in biomass partitioning. We found that Biyu, a drought-sensitive hybrid poplar clone, had significant relations among biomass of leaf, stem and root, showing allometric partitioning. Xiaoye, a drought-tolerant poplar clone native to semi-arid areas, on the contrary, showed tightly regulated biomass allocation following optimal partitioning theory. Biyu had higher nitrate reductase activity in the fine roots, while Xiaoye had higher nitrate reductase activity in the leaves. Biochemical analyses and measurements of fluorescence and gas exchange showed that Xiaoye maintained more stable chloroplast membranes and photosystem electron flow, showing higher water use efficiency and a higher resistance to drought. A nitrogen addition could improve leaf photosynthesis and growth both in Biyu and Xiaoye seedlings under drought conditions. We concluded that the two poplar clones showed different biomass allocation patterns and suggest that the site of nitrate assimilation may play a role in biomass partitioning under varying water and nitrogen availabilities.

Understanding the Saffron Corm Development-Insights into Histological and Metabolic Aspects.

The reproduction of Crocus sativus L., a sterile triploid plant, is carried out exclusively through corms, whose size determines the saffron yield. The development of daughter corms (DC) is supported by photoassimilates supplied by the leaves as well as by the mother corms (MC). While biomass partitioning during DC development is well studied, growth dynamics in terms of cell number and size, the involved meristems, as well as carbohydrate partition and allocation, are not yet fully understood. We conducted a comprehensive study into saffron corm growth dynamics at the macroscopic and microscopic levels. Variations in carbohydrate content and enzymatic activities related to sucrose metabolism in sources and sinks were measured. Two key meristems were identified. One is involved in vascular connections between DC and MC. The other is a thickening meristem responsible for DC enlargement. This research explains how the previously described phases of corm growth correlate with variations in cell division, enlargement dynamics, and carbohydrate partitioning among organs. Results also elucidated that the end of DC growth relates to a significant drop in MC root biomass, limiting the water supply for the DC growth, and establishing the onset of leaf wilting. The lack of starch accumulation in aged leaf cells is noteworthy, as is the accumulation of lipids. We hypothesize a signaling role of sugars in DC growth initiation, stop, and leaf aging. Finally, we established a predominant role of sucrose synthase as a sucrolytic enzyme in the maintenance of the high flux of carbon for starch synthesis in DC. Together, the obtained results pave the way for the definition of strategies leading to better control of saffron corm development.

Plant biomass partitioning in alpine meadows under different herbivores as influenced by soil bulk density and available nutrients

Biomass allocation is a key mechanism for understanding the response of alpine meadow plants to environmental changes. However, the two major theories of plant biomass partitioning, that is, optimal and equidistant allocation, are highly controversial. This study aimed to test these hypotheses by using the biomass allocation pattern of Qinghai–Tibetan Plateau alpine meadows under different herbivore assemblages and enclosures and to identify the key physicochemical factors driving changes in biomass allocation. The results showed that fencing and grazing lead to the allocation of more biomass to roots and shoots, respectively. Additionally, our results support the optimal allocation hypothesis, which is mainly regulated by changes in soil physicochemical properties. Specifically, the trade-off between aboveground- and belowground biomass negatively correlated with the soil bulk density, soil moisture, available nitrogen, and available phosphorus but positively correlated with available potassium. In terms of biomass trade-offs, co-grazing yaks and Tibetan sheep at a 1:6 ratio with moderate grazing intensity may be a reasonable method to use and protect alpine meadows on the Qinghai-Tibetan Plateau.