Source-sink Relationships Research Articles

Distribution of Indolic Glucosinolates in Different Developmental Stages and Tissues of 13 Varieties of Cabbage (Brassica oleracea L. var. capitata)

Cabbage (Brassica oleracea L. var. capitata) is an excellent source of glucosinolates (GLS) that could reduce the risk of chronic diseases. The purpose of this study was to investigate the biological traits, pigment contents, color, and GLS content of 13 cabbage varieties. This study found that there were significant differences in the GLS content for various developmental stages of cabbage varieties, and the accumulation of GLS in young leaves was higher than that in mature stages. In most of the samples, the GLS content accumulated in different parts and changed as inner leaf > middle leaf > condensed stem > root. Double haploids of the M18-15 variety may be good candidates for future breeding programs and consumers, due to their high GLS content (ranging from 201.10 to 396.25 nmol mg−1 FW). GLS also act as a defense substance, and the data related to GLS accumulation patterns in different leaf locations and root parts may be useful for understanding leaf defense mechanisms and potential source–sink relationships. In addition, the observed interspecific variability is beneficial for breeders to develop Brassica varieties with high GLS content, as well as for the development of new functional food additives.

Crops under past diversification and ongoing climate change: More than selection on nuclear genes for flowering.

Diversification and breeding following domestication and current climate change across the globe are the two most significant events experienced by major crops. Diversification of crops from their wild ancestors has favored dramatic changes in the plant's sensitivity to environment, significantly in transducing light inputs to the circadian clock, which allowed the growth of major crops in the shorter growing season in the Northern hemisphere. Historically, mutants and quantitative trait loci (QTL) mapping have facilitated the identification and cloning of genes underlying major changes of the clock and flowering regulation. Recent studies suggest that thermal plasticity of circadian clock output, not just the core genes that follow temperature compensation, was also under selection during diversification and breeding. Wild alleles that accelerate output rhythmicity could be beneficial for crop resilience. Furthermore, wild alleles with beneficial and flowering-independent effects under stress indicate their possible role in maintaining a balanced source-sink relationship, allowing productivity under climatic change. Because the chloroplast genome also regulates the plasticity of the clock output, mapping populations including cytonuclear interactions should be utilized in an integrated field and clock phenomics framework. We highlight the need to integrate physiological and developmental approaches (Physio-Devo) to gain a better understanding while re-domesticating wild gene alleles into modern cultivars to increase their robustness under abiotic heat and drought stresses.

Potential Foliar Chemicals for Enhancing Yield and Drought Tolerance in Leguminous Crops: A Review

In pulse crops, synchronized flowering altered the source-sink relationship due to the rapid translocation of nutrients from leaves to the developing pods. Additional nutrition through foliar feeding plays a vital role in pulse production by stimulating root development, nodulation, energy transformation, various metabolic processes and increasing pod setting, thereby increasing the yield. Many researchers are trying to reduce transpiration losses, flower shedding and maximizing productivity, foliar application of nutrient formulations and growth regulators in pulses. Thus, the foliar application of macro and micronutrients and growth regulators is considered an efficient and economical method of supplementing part of the nutrient requirements and moisture stress tolerance at critical stages. The PPFM (Pink pigmented facultative methylobacteria), when used as a foliar spray, it releases osmoprotectants (sugars and alcohols) on the surface of the plants and it increases chlorophyll content, thereby increasing the photosynthetic efficiency and makes drought tolerance ability of plants. This matrix helped to protect the plants from desiccation and high temperatures. Whereas potassium as spray also enhances drought tolerance in plants by mitigating harmful effects by increasing translocation, maintaining water balance and increasing pod filling. Further, Salicylic acid is an endogenous growth regulator of phenolic nature, which regulates physiological processes to mitigate stress, acts as a chelate for phosphorous uptake, increases pod setting, flowering and grain yield. Pulse wonder decreases flower shedding, increases yield by up to 20% and offers moisture stress tolerance.

Reducing the sink/source ratio of on-date palm plants during fruit growth has physiological and biochemical impacts on the shift in source-sink limitations.

The present study examined the impact of reducing the 'sink' on the 'source' in On-palms with a bunch number greater than eight. The capacity of leaves and fruit, as well as assimilate loading and unloading in phloem, restrict plant growth and yield. The study evaluated yield components, as well as photosynthetic and hormonal feedback, resulting from source-sink relationships. During the mid-Kimri, removing bunches from On-trees stabilized yield components and fruit size, suggesting that On-trees have a sink limitation. Bunch thinning boosted these indicators compared to normal trees with a bunch number between six and eight inclusive, indicating that On-trees had source limitations. In mid-Khalal, the treatments presented a type of source and sink limitation that is opposite to mid-Kimri. The thinning techniques addressed the source-sink limitation by adjusting the additional carbon allocation. This resulted in an increase of non-reducing sugars and starch in different organs, whereas reducing sugars decreased. These adjustments were made to reduce sucrose-phosphate synthase and sucrose synthase activity, raising invertase activity, lowering indole-3-acetic acid, zeatin, gibberellin, and abscisic acid hormone levels in fruits, as well as lowering trehalose production in organs. Levels of hormones, enzymes, and trehalose showed less variation during bunch thinning and source limitation compared to bunch removal and sink limitation. At Rutab, thinning types demonstrated the source limitation of On-trees. Bunch removal and bunch thinning by removing the source-sink limitation had the greatest effect on increasing yield components and fruit size, respectively. To improve the quality and quantity of fruit, it is important to use both thinning techniques simultaneously. © 2023 Society of Chemical Industry.

Influence of 24-Epibrassinolide on the Energetic Parameters and Early Stages of Growth and Development in Seedlings of Two Maize (Zea mays L.) Genotypes

Brassinosteroids (BRs) are a class of plant hormones that play important roles in regulating various physiological and developmental processes in plants. One of the most effective BRs involved in modulating crop growth is 24-epibrassinolide (24-EBL). The effects of different concentrations of 24-EBL on various biochemical and biophysical parameters critical to early growth stages and seedling development were investigated using two maize hybrids, ‘ZP 434’ (a new-generation hybrid) and ‘ZP 704’ (an older-generation hybrid). The evaluation of results is based on measurements of germination percentage, morphometric parameters, redox status, comparative analysis of thermodynamic parameters (such as Gibbs free energy, enthalpy, entropy), and the concentration of specific sugars in different parts of maize seedlings. The results indicate that the germination and initial growth of maize seedlings are influenced by the flow of crucial sugars from the remaining seed (as a source of nutrients) towards the plumule and radicle (as sink organs). Furthermore, alterations in Gibbs free energy play a significant role in these sugar transfers within the maize seedlings. The seed germination was most affected by the highest concentrations of 24-EBL, showing inhibitory effects, whereas lower and moderate concentrations of exogenously added 24-EBL exhibited a beneficial influence on the initial phases of seedling growth. The mentioned approach gives new insights into source–sink relationships and can be used as a quantitative measure of the germination energy, which until now has been a qualitative criterion in seed science.

Agronomic and Physiological Performances of High-Quality Indica Rice under Moderate and High-Nitrogen Conditions in Southern China

High-quality (i.e., higher appearance and eating quality) rice (Oryza sativa L.) is being increasingly and widely planted in China with the improvement of people’s living standards and the achievement of rice breeding efforts in recent years. However, the agronomic and physiological performances of high-quality indica rice (HQIR) under different nitrogen (N) application conditions in southern China are little known. Two-year consecutive field experiments were conducted with two HQIR and two ordinary-quality indica rice (OQIR) varieties under moderate and high-N application rates, with yield and yield components, biomass, N uptake, and their related traits, being investigated. We found that grain yields of HQIR were slightly decreased, but grain yields of OQIR were significantly increased by 7.0–9.6% under a high N rate, compared with a moderate N rate within two years. Thereby, OQIR produced a 5.7–14.7% and 18.7–25.6% higher grain yield than HQIR under moderate and high N rates, respectively. The different responses of grain yield to N application rates were mainly due to a decreased grain setting rate in HQIR and increased spikelets m−2 in OQIR under a high N rate. Furthermore, a high N rate significantly reduced pre-anthesis AE (apparent exportation of pre-anthesis stem and leaf blade dry matter) and improved the grain-leaf area ratio, while it did not increase post-anthesis dry matter, compared with a moderate N rate in HQIR, which might result in carbon-metabolic deterioration, an imbalance of the source–sink relationship and, subsequently, a lower supply of carbohydrate in panicle. Our results suggest that a moderate N rate (165 kg N ha−1) is beneficial for the HQIR varieties to balance the maximum grain yield and high quality in southern China.

Effects of physiological integration on nitrogen use efficiency of moso bamboo in homogeneous and heterogeneous environments.

Moso bamboo is one of the important clonal plants with complex underground rhizome-root system. Ramets connected by rhizome can translocate and share nitrogen (N), which may affect the nitrogen use efficiency (NUE) of moso bamboo. The aims of this study were to investigate the mechanisms of N physiological integration and its relationship with NUE of moso bamboo. A pot experiment was conducted to trace the movement of 15N between the connected ramets of moso bamboo in both homogeneous and heterogeneous N environments. Results showed that N translocation within clonal fragments of moso bamboo was detected in both homogeneous and heterogeneous environments. The intensity of physiological integration (IPI) was significantly lower in homogeneous environments than that in heterogeneous environments. 15N translocation between the connected ramtes of moso bamboo was determined by the source-sink relationship in heterogeneous environments, and the 15N allocation of the fertilized ramet was higher than that of the connected unfertilized ramet. The NUE of connected treatment was significantly higher than that of severed treatment, which suggested that physiological integration significantly improved the NUE of moso bamboo. In addition, the NUE of moso bamboo was significantly higher in heterogeneous environments than that in homogeneous environments. The contribution rate of physiological integration (CPI) on NUE in heterogeneous environments was significantly higher than that in homogenous environments. These results will provide theoretical basis for precision fertilization in moso bamboo forests.

Effects of antibiotics on the endophyte and phyllosphere bacterial communities of lotus from above and below surface water in a typical shallow lake

Antibiotics are ubiquitous pollutants that are widely found in aquatic ecosystems, where the bacterial community of aquatic plants is influenced by antibiotics. However, differences between endophyte and phyllosphere bacteria of Lotus from above and below surface water remains unclear. Lotus samples from above and below the surface water were collected to investigate the differences in endophyte and phyllosphere bacteria and dominant environmental factors in regions with low (L-) and high (H-) total antibiotic levels. There were significant differences in Shannon diversity between endophyte and phyllosphere bacteria except between the below-surface water phyllosphere bacteria and below-surface water endophytes in both L-antibiotic and H-antibiotic regions, with higher values for phyllosphere bacteria. The dominant phylum in all phyllosphere samples was Proteobacteria (76.1%–92.5%), while Cyanobacteria (47.8%–81.1%) was dominant in all endophyte samples. The dominant source of above-surface water endophytes was below-surface water endophytes (83.68–91.25%), below-surface water phyllosphere bacteria (48.43–55.91%) for above-surface water phyllosphere bacteria, and above-surface water endophytes (53.83–61.80%) for below-surface water endophytes, while the dominant contributor to the below-surface water phyllosphere bacteria was also below-surface water endophytes (52.96–61.00%) in two regions, indicating that antibiotic stress changed the sink‒source relationship between endophytes and phyllosphere bacteria. The physical-chemical properties of surface water and sediments could be responsible for the variations in the above- and below-surface water endophytes and phyllosphere bacteria in both regions. It is suggested that antibiotics may have a substantial effect on endophyte and phyllosphere bacterial community.

The Effects of Paclobutrazol Seed Soaking on Biomass Production and Yield Formation in Direct-Seeded Rice

Direct-seeded rice has been widely adopted in Asia in recent years. However, its low and unstable yields severely limit the increase in rice production and directly affect food security. The aim of this research was to investigate the effects of different concentrations of paclobutrazol seed soaking on the biomass production and yield formation of direct-seeded rice and to find the optimal concentrations to provide a theoretical basis for the high-yielding cultivation of direct-seeded rice. Two rice varieties, Jiyujing and Jijing305, were used in this experiment, and the seeds were soaked in paclobutrazol at concentrations of 0, 50, 100, 150, and 200 mg L−1. The appropriate concentration of paclobutrazol seed soaking increased the yield of direct-seeded rice; this was attributed to the increase in the spikelet per unit area and the seed setting rate. However, the too-high paclobutrazol concentration was not conducive to a yield increase. Regression analysis showed that the appropriate concentration of paclobutrazol seed soaking was 100–105 mg L−1. The appropriate concentration of paclobutrazol for seed soaking ensured the seedling emergence rate; improved the seedling quality, stem tillers, and productive tillers; increased the efficient leaf area, chlorophyll content, and net photosynthetic rate, resulting in an increase in dry matter accumulation; coordinated the source-sink relationship and dry matter distribution; and promoted the material translocation from the “source” to the “sink”. In conclusion, using the appropriate concentration of paclobutrazol for seed soaking is an effective means of obtaining high yields of direct-seeded rice.

Physiological integration improves nitrogen use efficiency of moso bamboo: An isotopic (15N) assessment

Physiological integration is a means of adapting to the natural selection of moso bamboo. Connected ramets can translocate and share nitrogen (N). This phenomenon may affect the nitrogen use efficiency (NUE) of moso bamboo. The aims of this study were to investigate the characteristics of N physiological integration and its relationship with NUE of moso bamboo. We established an in-situ experiment to trace the movement of 15N between connected ramets (parent and offspring ramets) of moso bamboo in both homogeneous and heterogeneous N conditions. Results showed that 15N sharing within the clonal systems of moso bamboo was detected in both homogeneous and heterogeneous environments, and 15N translocation was bidirectional between the connected ramets. The intensity of physiological integration (IPI) was relatively low in homogeneous environments, and the connected ramets of moso bamboo were selfish. 15N translocation between the connected ramtes of moso bamboo was determined by the demand-driven source-sink relationship in heterogeneous environments, and the fertilized ramets of moso bamboo were selfish. The NUE of the connected treatment was significantly higher than that of the severed treatment, illustrating that physiological integration significantly improved the NUE of moso bamboo. Additionally, the NUE in heterogeneous environments was significantly higher than that in homogeneous environments. These results clearly demonstrate that N is readily translocated between the connected ramets of moso bamboo, particularly in heterogeneous environments, which provides reference for precision fertilization management in moso bamboo forests.

Functional growth analysis of diploid potato varieties (Solanum tuberosum Phureja group)

The growth analysis is relevant to understanding and comparing in terms of physiological and productive behavior varieties. The study aims to determine the accumulation and distribution of dry matter through different phenological stages of development in four diploid potato varieties. For this, in a randomized complete block design with three replications, four varieties of diploid potato were evaluated: Paola, Violeta, Primavera, and Paysandú. Based on direct measurements of leaf area and dry matter of each organ, it was computed the growth indices of relative growth rate (RGR), net assimilation rate (NAR), leaf area relation (LAR), and source-sink relation. The duration of development stages of flowering, fruit, and tuber development was measured in terms of thermal time. Furthermore, the number of stems, stolons, and tubers was measured, and the yield was registered at the cycle end. The varieties Paola and Primavera reached a greater accumulation of dry matter in each organ and a greater number of tubers by plant about the varieties Paysandú and Violeta. The organs with the greater biomass accumulated were the leaves, stems, and tubers. The source and demand power had a considerable correlation between the NAR and RGR, which increased toward the end of the cycle for Paola and Primavera varieties. The yield and the beginning and duration of the growth stages were related to the season and the varieties.

Drought Stress-Induced Alterations in Source–Sink Relationships in Barley During Grain Development

Drought Stress-Induced Alterations in Source–Sink Relationships in Barley During Grain Development

The patterns and driving forces of dengue invasions in China

BackgroundGlobal connectivity and environmental change pose continuous threats to dengue invasions from worldwide to China. However, the intrinsic relationship on introduction and outbreak risks of dengue driven by the landscape features are still unknown. This study aimed to map the patterns on source-sink relation of dengue cases and assess the driving forces for dengue invasions in China.MethodsWe identified the local and imported cases (2006–2020) and assembled the datasets on environmental conditions. The vector auto-regression model was applied to detect the cross-relations of source-sink patterns. We selected the major environmental drivers via the Boruta algorithm to assess the driving forces in dengue outbreak dynamics by applying generalized additive models. We reconstructed the internal connections among imported cases, local cases, and external environmental drivers using the structural equation modeling.ResultsFrom 2006 to 2020, 81,652 local dengue cases and 12,701 imported dengue cases in China were reported. The hotspots of dengue introductions and outbreaks were in southeast and southwest China, originating from South and Southeast Asia. Oversea-imported dengue cases, as the Granger-cause, were the initial driver of the dengue dynamic; the suitable local bio-socioecological environment is the fundamental factor for dengue epidemics. The Bio8 [odds ratio (OR) = 2.11, 95% confidence interval (CI): 1.67–2.68], Bio9 (OR = 291.62, 95% CI: 125.63–676.89), Bio15 (OR = 4.15, 95% CI: 3.30–5.24), normalized difference vegetation index in March (OR = 1.27, 95% CI: 1.06–1.51) and July (OR = 1.04, 95% CI: 1.00–1.07), and the imported cases are the major drivers of dengue local transmissions (OR = 4.79, 95% CI: 4.34–5.28). The intermediary effect of an index on population and economic development to local cases via the path of imported cases was detected in the dengue dynamic system.ConclusionsDengue outbreaks in China are triggered by introductions of imported cases and boosted by landscape features and connectivity. Our research will contribute to developing nature-based solutions for dengue surveillance, mitigation, and control from a socio-ecological perspective based on invasion ecology theories to control and prevent future dengue invasion and localization.Graphical

Combination of suitable planting density and nitrogen rate for high yield maize and their source-sink relationship in Northwest China.

Increasing crop yield per unit area by increasing planting density is essential to ensure food security. However, the optimal combination of planting density and N application for high-yielding maize and its source-sink characteristics need to be more clearly understood. A two-year field experiment was conducted combining three planting densities (D1: 70,000 plants ha-1 ；D2: 100,000 plants ha-1 ；D3: 130,000 plants ha-1 ) and three nitrogen rates (N1: 150 kg N hm-2 , N2: 350 kg N hm-2 , N3: 450 kg N hm-2 ). The results showed that increasing planting density significantly increased leaf area index and grain yield, but negatively affected ear traits. The Richards model was used to fit the dynamic changes of dry matter accumulation of maize under different treatments, and the fitting results were good. Increasing planting density increased population yield while limiting the development of individual plants, bringing the period of rapid dry matter accumulation to an early end and accelerating leaf senescence. Appropriate N rate could prolong the period of rapid accumulation of dry matter in maize, increase the 100-kernel weight. Increasing planting density enhanced post-silking dry matter accumulation to a lesser extent, and the source-sink relationship of the maize population gradually developed from sink limitation to source limitation with increasing planting density. The decrease in yield due to the insufficient source strength to meet the sink demand at too high densities was the reason that limited further improvement of the optimal planting density. Appropriate N rate facilitated the realization of yield potential at high density. This article is protected by copyright. All rights reserved.

Effects of fruit load on growth, photosynthesis, biochemical characteristics, and fruit quality of Camellia oleifera

Camellia oleifera Abel is one of the four major woody oil species that produce edible oil from seeds. Nevertheless, its oil yield is comparably low, due to an imbalance in its source–sink relationship caused by its alternate bearing cycle. In this study, we conducted a pot experiment using 5-year-old C. oleifera ‘Huaxin’ young plants to examine the source–sink relationship and determine the optimal fruit load for oil production that ensures maximum economic value for C. oleifera. From April to October, the C. oleifera young plants were subjected to different leaf:fruit ratios: no fruit (control, CK), low fruit load (FL1, leaf:fruit ratio of 36:1), medium fruit load (FL2, leaf:fruit ratio of 18:1), and high fruit load (FL3, leaf:fruit ratio of 9:1). The results showed that the FL2 and FL3 treatments significantly reduced plant height, stem diameter, and flower bud differentiation from August to October, compared with the control. The net photosynthetic rate (Pn) and stomatal conductivity (Gs) of new leaves on clear days from June to August were decreased in the FL2 and FL3 treatments, compared with the control. Medium and high fruit loads (FL2 and FL3 treatments) and prolonged growth duration led to greater reductions in fruit size, weight, seed kernel oil content, oil production per plant, oil body volume, and distribution area, compared with the FL1 treatment. However, stearic acid and oleic acid contents were significantly higher in camellia oil obtained from the FL1 treatment than in camellia oil obtained from the FL2 and FL3 treatments. Thus, a leaf:fruit ratio of 36:1 is recommended to ensure proper C. oleifera ‘Huaxin’ growth and yield, and higher fruit loads should be avoided.

Does the plant growth regulator paclobutrazol enhance root growth of maize exposed to drought stress during flowering?

AbstractDue to climate change, crop production will increasingly be affected by water limitation, causing remarkable decreases in grain yields of cereals. Plant growth regulators such as paclobutrazol (PAC) have been shown to protect plants from detrimental impacts of drought stress, and improvement of root growth and antioxidant activity were identified as main reasons for their positive effect. A container experiment was conducted with two maize (Zea mays L.) cultivars, Galactus and Fabregas, to investigate how PAC application affects root growth and grain yield under stress conditions. At growth stage V8, the plants were treated once with PAC (0, 2, or 3 mg PAC per plant), and concomitantly reduction in soil water content commenced until 30–35% of the maximum water‐holding capacity (WHC) was achieved. The plants were exposed to this drought condition for three weeks during flowering as the critical period for kernel setting. Both factors, PAC application and drought stress, caused decreases in plant height, whereas total leaf area was unchanged and transpiration rate was significantly reduced by water limitation only. Flowering was almost unaffected by PAC treatment; yet, drought stress significantly delayed start of silking. The straw yield was decreased due to PAC and drought stress, and an improvement of the harvest index was obtained for drought‐stressed Galactus plants with PAC application. Grain yield was unaffected by PAC application, whereas drought stress caused significant decreases by 15% on average of both cultivars. The kernel number of drought‐stressed Galactus plants was increased after PAC treatment, but concurrently smaller kernels were produced. Water limitation generally decreased kernel number. Drought‐stressed Fabregas plants consumed less water after PAC treatment, resulting in significant improvements of water‐use efficiency (WUEgrain) during silking and thus most likely alleviating stress intensity. For both cultivars, PAC treatment and water limitation showed almost no significant impact on root dry matter, root length density, and root surface area, either determined for different soil layers down to 80 cm or on a per‐plant basis. It is concluded that grain yield performance of maize plants, exposed to water limitation during flowering, was not source‐limited but sink‐limited. Consequently, even if PAC can cause improvement of antioxidant activity and photosynthesis, due to sufficient availability of assimilates in the maize kernels a positive effect on grain yield is improbable. Considering source–sink relationships during flowering and kernel set, enhanced root growth due to PAC treatment did apparently not occur.

Source–Sink manipulations have major implications for grapevine berry and wine flavonoids and aromas that go beyond the changes in berry sugar accumulation

Sugar levels in grape berries are necessary for wine production but also, they are the main driver of most ripening processes. Sugar levels are very responsive to canopy and crop load adjustments. The aim of this study is to test the effect of different levels of defoliation and cluster thinning on grape ripening and wine composition. ‘Cabernet sauvignon’ grapevines (Vitis vinifera L.) were subjected to defoliation (keeping 100 %, 66 % and 33 % of the leaves) and fruit thinning treatments (keeping 100 %, 66 % and 33 % of the clusters) combined in a factorial design. The experiment was repeated for 2 consecutive seasons (2017 and 2018) and the plants were left untreated for a third season (2019) to observe the carry-over effects of the treatments. The treatments implied precise adjustments of leaf and cluster numbers. However, the proportion of leaf area to fruit mass tended to compensate each other and interact resulting in smaller differences in leaf area or fruit mass by harvest. Berry mass was strongly reduced by defoliation even in the subsequent season where no defoliation was applied. Berry ripening indicators (soluble solids, acidity and anthocyanin levels) were also more affected by defoliation than fruit thinning. Anthocyanin profile was shifted to a higher proportion of Malvidin-derived anthocyanins for defoliated vines and lower proportion of Malvidin-derived anthocyanins in the case of thinned vines. However, when it came down to wine, the physicochemical parameters as well as the aroma profile were more affected by cluster thinning. There was a clear relationship between sugar levels of the unfermented must and many wine-aroma compounds. Green aromas (2-isobutyl-3-methoxypyrazine, hexanol and cis-3-Hexen-1-ol) were among those presenting a negative correlation to must sugar whereas other compounds like Isobutyric acid, Benzyl alcohol, 1-Octen-3-ol and γ-Nonalactone had a positive correlation. This study reveals a higher level of complexity of source sink relations where leaves and clusters do not only act as a source and a sink of carbon, respectively. Therefore, the results of this study should be considered before making comparisons of leaf area to fruit mass ratios across different vine-growing systems.

Effects of NSC in different organs and at different growth stages on the yield of oil peony Fengdan with different ages.

Non-structural carbohydrates (NSC) as resource reserves of plants play important roles in energy supply for normal growth and reproduction under environmental stress. The yield of perennial crops is mainly determined by the carbohydrate production and allocation in the current growth season, as well as the re-allocation of NSC reserves. However, the contribution of NSC to crop yield has not been fully determined. Fengdan (Paeonia ostii) is a variety of oil Peony that is newly developed in China. The effects of tree age and NSC on yield were examined by investigated the variations of biomass, soluble sugars, starch, and NSC in the organ and whole tree levels in the dormant and ripening stages of Fengdan populations with 4-, 6-, and 8-year-old in 2020 and 5-, 7-, and 9- year old in 2021. Results showed that the biomass, yield (seed biomass), soluble sugars, starch, and NSC reserve of Fengdan at the whole tree level increased with the increase in age. Although consistent correlations were observed between soluble sugars, starch and NSC storage, and yield among the plants with different ages, Fengdan showed allometric growth relationships between the accumulation of soluble sugars, starch, and NSC and yield and biomass (standardized major axis analyses slope b ≠ 1). Tree age significantly affected biomass and its allocation and NSC levels, especially the yield of Fengdan plants. The results of the investigation of the variations in the relationships between the yield and seasonal fluctuations of NSC and biomass indicate that roots is the key storage structure, whereas stems both serve as sink and/or source functions for the adult (7-9a) plants. NSC level, particularly the concentration of soluble sugars, in stems mainly influences Fengdan yield. These findings together provide new insights into the mechanisms underlying the yield formation of Fengdan and have implications for manipulating sink-source relationship to achieve high yield.

Quantitative Analysis of Source-Sink Relationships in Two Potato Varieties under Different Nitrogen Application Rates

Nitrogen is an essential nutrient for plant growth. However, the excessive use of nitrogen fertilizers not only increases production cost, but also has negative a impact on the environment. The purpose of this study was to quantify the source-sink characteristics and length of each growth stage in two potato varieties under different nitrogen application rates. This clarifies the source-sink coordination characteristics of the nitrogen-efficient variety and the source-sink coordination mechanisms of high nitrogen use efficiency (NUE). Field experiments were conducted in 2019, 2020, and 2021 using a split-plot design, with a nitrogen application rate of (0; 150 kg·ha−1; 300 kg·ha−1) as the main plot and variety (J, nitrogen-efficient variety Jizhang 12; Y, nitrogen-inefficient variety Youjia 70) as the subplot. The results showed that the yield and NUE of Jizhang 12 at 300 kg·ha−1 were, on average, 90.73% and 75.15% higher than those of Youjia 70, respectively. The NUE and nitrogen utilization efficiency of Jizhang 12 increased on average, with decreasing N application at 68.66% and 24.53%, which were higher than those of Youjia 70 at 62.89% and 10.86%. Quantitative analysis of the source and sink showed that the Jizhang 12 had a higher source and sink capacity of 23.45 g and 51.85 g, respectively, and the maximum source and sink activity was on average 0.28 g·plant−1·d−1 and 1.47 g·plant−1·d−1 higher, and the growth period of the source and sink was on average 24 days and 7 days longer, respectively. On the basis of these results, the nitrogen-efficient varieties had a higher yield base and a smaller reduction in NUE with reduced N application. In terms of source-sink growth, N-efficient varieties lasted longer at the seedling and tuber initiation stages, when potatoes grew above ground and source organs grew for longer periods, providing a solid foundation for later sink growth, as evidenced by their higher source-sink activity, capacity, and growth time than N-inefficient varieties.

Improved cotton yield: Can we achieve this goal by regulating the coordination of source and sink?

Cotton is one of the major cash crops globally. It is characterized by determinate growth and multiple fruiting, which makes the source-sink contradiction more obvious. Coordination between source and sink is crucial for normal growth, yield, and quality of cotton. Numerous studies reported how the assimilate transport and distribution under varying environmental cues affected crop yields. However, less is known about the functional mechanism underlying the assimilate transport between source and sink, and how their distribution impacts cotton growth. Here, we provided an overview of the assimilate transport and distribution mechanisms , and discussed the regulatory mechanisms involved in source-sink balance in relation to cotton yield. Therefore, this review enriched our knowledge of the regulatory mechanism involved in source-sink relationship for improved cotton yield.