Accumulation Of Assimilates Research Articles

SHORT-ROOT specifically functions in the chalazal region to modulate assimilate partitioning into seeds.

Nourishing the embryo with endosperm and enclosing both embryo and endosperm in the seed coat are two important evolutionary innovations. Seed coat is conventionally viewed as a protective layer that functions after the seed has matured. Here, we challenge this notion by showing that a subregion of the seed coat, termed the chalazal seed coat (CZSC), is geared to gate seed nutrition loading in developing seeds. The CZSC develops the coordinative system comprising the apoplastic isolation, mediated by the restricted suberization, and the active transport, mediated by the specific expression of a variety of transporters, at as early as the globular embryo stage in both Arabidopsis and soybean seeds. This coordinated system in the CZSC disrupts the vascular continuum to the maternal tissues and forces the nutrient transport into selective and active absorption. We further reveal that the precision of the spatiotemporal suberin deposition and transporter expression is controlled by the regulatory hierarchy of SHR-MYBs cascades. Our results provide a mechanistic insight into the assimilate accumulation in dicot seeds.

Excellent Canopy Structure in Soybeans Can Improve Their Photosynthetic Performance and Increase Yield

In the maize-soybean intercropping system, varying degrees of maize leaf shading are an important factor that reduces the uniformity of light penetration within the soybean canopy, altering the soybean canopy structure. Quantitative analysis of the relationship between the soybean canopy structure and canopy photosynthesis helps with breeding shade-tolerant soybean varieties for intercropping systems. This study examined the canopy structure and photosynthesis of intercropped soybeans during the shading stress period (28 days before the corn harvest), the high light adaptation period (15 days after the corn harvest), and the recovery period (35 and 55 days after the corn harvest), using a field high-throughput phenotyping platform and a plant gas exchange testing system (CAPTS). Additionally, indoor shading experiments were conducted for validation. The results indicate that shade-tolerant soybean varieties (STV varieties) have significantly higher yields than shade-sensitive soybean varieties (SSV varieties). This is attributable to the STV varieties having a larger top area, lateral width, and lateral external rectangular area. Compared to the SSV varieties, the four top areas of the STV varieties are, on average, 52.09%, 72.05%, and 61.37% higher during the shading stress, high light adaptation, and recovery periods, respectively. Furthermore, the average maximum growth rates (GRs) for the side mean width (SMW) and side rectangle area (SRA) of the STV varieties are 62.92% and 22.13% in the field, and 83.36% and 55.53% in the indoor environment, respectively. This results in a lower canopy overlap in STV varieties, leading to a more uniform light distribution within the canopy, which is reflected in higher photosynthetic rates (Pn), apparent quantum efficiency, and whole-leaf photosynthetic potential (WLPP) for the STV varieties, thereby enhancing their adaptability to shading stress. Above-ground dry matter accumulation was higher in STV varieties, with more assimilates stored in the source and sink, promoting assimilate accumulation in the grains. These results provide new insights into how the superior canopy structure and photosynthesis of shade-tolerant soybean varieties contribute to increased yield.

Investigating the impacts of different degrees of deficit irrigation and nitrogen interactions on assimilate translocation, yield, and resource use efficiencies in winter wheat

Water and nitrogen (N) are recognized as the primary determinants influencing the development and output of winter wheat. They affect the growth of winter wheat not only through their own changes, but also through their interaction. The translocation and accumulation of pre- and post-anthesis assimilates (including dry matter and N) are important physiological processes in winter wheat, which are closely related to the resource use efficiency and yield. However, a dearth of research exists that examines the complex interplay between varying water levels, especially severe water deficit, and N deficiency levels on the growth dynamics of winter wheat. The purpose of this study was to quantify and compare the effects of different degrees of water deficit and N interaction on assimilate translocation, water and N use efficiency and yield of winter wheat. A four-year long-term field experiment conducted under the rain-out shelter including four irrigation and two N levels was launched during 2019–2023. This method avoided the impact of precipitation on water treatment and helped to achieve serious water deficit treatment. The findings indicated that the higher N application improved the wheat's ability by 49.6 % - 362.3 % to utilize the available soil water. The pre- and post-anthesis translocation and accumulation of assimilates (including dry matter and N) in winter wheat increase alongside elevated levels of water and N application, except under severe water deficit treatment. Plants under mild to moderate water deficit were better able to translocate the pre-anthesis assimilates. However, the severe water deficit hindered the re-translocation of assimilates before anthesis. Providing additional N during periods of severe water scarcity leads to a 13.4 % - 44.7 % reduction in water use efficiency (WUE). Furthermore, both the irrigation water use efficiency and WUE diminished by 10.3 % - 60.5 % and 4.5 % - 41.4 % with higher levels of irrigation, while improved by 24.4 % - 48.2 % and 12.6 % - 39.4 % with higher N application rates. Conversely, N partial factor productivity and N use efficiency followed the opposite trend. Similar to WUE, increasing N application under severe water deficit would result in a yield reduction of 38.7 %. The reduction in crop yield resulting from severe water stress was primarily ascribed to the decline in the kernels number per spike (up to 74.9 %), with the reduction in spike number per unit area following closely behind (up to 29.1 %). This integrated approach, combining resource use efficiency with a detailed assessment of assimilate dynamics, provides a holistic view of how water and N management strategies impact winter wheat performance. The findings will offer precise insights for developing targeted irrigation and N scheduling strategies for sustaining both winter wheat production and environmental sustainability.

Фотосинтетическая активность подроста хвойных в связи с промышленными рубками

The functioning of coniferous undergrowth of preliminary and subsequent generations after industrial felling was considered in the middle taiga subzone of the Komi Republic. Using spectrophotometric and gasometric methods we analyzed the pigment activity, photosynthetic, and respiratory abilities of the assimilation apparatus of pine (Pinus sylvestris L.) and spruce (Picea obovata Ledeb.) undergrowth at the 3- and 10-year old clearings. The pigment apparatus functional rearrangement of the preliminary generation spruce undergrowth at clearings was found. Needles adapt to environmental conditions at the pigment system level by changing the content and ratio of chlorophylls and carotenoids. Changes in plastids in the spruce undergrowth at the 3-year clearings occurred due to a decrease in chlorophyll and carotenoid concentrations, and at the 10-year clearings due to activation of pigment synthesis which affects the carbon dioxide absorption in chloroplasts. The assimilation apparatus of spruce undergrowth at clearing absorbs CO2 by 1.4 and 1.8 time more actively than that under the forest canopy. The photosynthetic and respiratory abilities of spruce needles at clearings do not differ. This indicates a stable level of important vital processes for the studied undergrowth at clearings during ten years after felling. Pine and spruce undergrowth needles are able to absorb CO2 at a fairly high rate up to 5.73 and 2.7 μmol CO2/(m2 · s) respectively. This rate contributes to the accumulation of assimilates in pine needles and their use for growth which logically increases the productivity of undergrowth at clearings. In general, the functional organization of spruce and pine undergrowth assimilating organs ensures their growth and favors the successful restoration of conifers at clearings in the middle taiga subzone of the European North-East.

Shading and waterlogging interactions exacerbate summer maize yield losses by reducing assimilate accumulation and remobilization processes

Persistent overcast rain was an essential limiting factor for summer maize production, of which immediate impact was the dual pressure of waterlogging and shading. However, the mechanism of independent and combined effects of waterlogging and shading induced maize yield losses are rarely studied, especially at different growth stages. Denghai 605 (DH605) was selected to be subjected shading, waterlogging, and their combined stress at the 3rd leaf stage (V3), the 6th leaf stage (V6), and tasseling stage (VT). Results showed that shading, waterlogging and their combination significantly limited the expansion of leaf area, and decreased leaf net photosynthetic rate (Pn) and net assimilation rate (NAR), thus reducing the crop growth rate (CGR) and biomass accumulation. At the same time, compared to control, the process of lignin synthesis was inhibited under stressed treatment, resulting in reduced stem mechanical strength and a poor development of the vascular system, of which change significantly reduced efficiency of assimilate remobilization to the ear and ultimately grain yield. The most significant effects of waterlogging and combined stresses on yield were occurred at V3 stage, followed by the V6 and VT stages. The most significant effects of shading were occurred at VT stage, followed by the V6 and V3 stages. Moreover, the compound stress exacerbated the damage brought about by a single stress. It is predicted that climate change will increase the frequency of abiotic stress assemblages, and the results of these findings provide some direction for further research on maize breeding in summer maize under continuous rainy conditions in the future.

Physiology and development of grafted dwarf cashew seedlings under different fertilization doses and irrigated with saline water

Salinity is one of the primary challenges faced by irrigated agriculture in semi-arid regions. This study aimed to investigate the effects of fertilization on the development of cashew seedlings irrigated with water of varying salinity levels. The research was conducted in a protected environment at Embrapa Agroindústria Tropical, Fortaleza, using grafted seedlings of the BRS 189 clone on CCP 06 rootstock. The treatments resulted from the combination of three levels of NPK fertilization (control - without fertilization, 50% less than conventional nutrition, and 100% of conventional nutrition used by the crop), which was incorporated into the substrate before sowing CCP 06, with four salinity levels (ECa of 0.8, 4.0, 7.0, and 10.0 dS m-1) of the irrigation water for the seedlings. Gas exchange, assimilate accumulation, growth, and nutrient content in the leaves, stems, and roots of the seedlings were evaluated 90 days after grafting. The data were subjected to analysis of variance, and when a significant effect was observed, the Tukey test was performed, while quantitative data were subjected to regression analysis. Overall, fertilization levels did not influence seedling growth. Fertilization did not interfere with photosynthate production, which performed better when the seedlings were subjected to a salinity of 7.0 dS m-1. The application of NPK to the substrate resulted in higher levels of nitrogen in the leaves, while phosphorus content decreased, and foliar potassium was not influenced by fertilization.

Phenotypic and transcriptome profiling of spikes reveals the regulation of light regimens on spike growth and fertile floret number in wheat.

The spike growth phase is critical for the establishment of fertile floret (grain) numbers in wheat (Triticum aestivum L.). Then, how to shorten the spike growth phase and increase grain number synergistically? Here, we showed high-resolution analyses of floret primordia(FP) number, morphology and spike transcriptomes during the spike growth phase under three light regimens. The development of all FP in a spike could be divided into four distinct stages: differentiation (Stage I), differentiation and morphology development concurrently (Stage II), morphology development (Stage III), and polarization (Stage IV). Compared to the short photoperiod, the long photoperiod shortened spike growth and stimulated early flowering by shortening Stage III; however, this reduced assimilate accumulation, resulting in fertile floret loss. Interestingly, long photoperiod supplemented with red light shortened the time required to complete Stages I-II, then raised assimilates supply in the spike and promoted anther development before polarization initiation, thereby increasing fertile FP number during Stage III, and finally maintained fertile FP development during Stage IV until they became fertile florets via a predicted dynamic gene network. Our findings proposed a light regimen, critical stagesand candidate regulators that achieved a shorter spike growth phase and a higher fertile floret number in wheat.

Spatiotemporal dynamics of the foxtail millet transcriptome during grain filling

AbstractFlag leaf, stem, and grain are all important for endosperm development (grain filling) in cereal crops. However, joint analysis of these three tissues during grain filling is limited. Hence, we employed RNA‐seq to compare the transcription dynamics in flag leaf, stem, and grain at different stages during grain filling. The differentially expressed genes (DEGs) between different tissues and stages were identified. The number of DEGs was increased from stage 2 to stage 4 in leaf and grain, while the number of DEGs was decreased in the stem. Through WGCNA analysis, genes associated with photosynthesis were specifically changed in flag leaves during grain filling. Lignin and branched chain amino acid synthesis‐related genes were specifically expressed in stem and grain, respectively. The phytohormone signal transduction and sucrose‐starch conversion pathway in stem and grain together promoted the offloading of assimilates from stem to grain and the assimilate accumulation in grain. These results provide new insights for further investigations on molecular regulatory mechanisms among different tissues of grain filling, and also provide a new idea for improvement of yield and quality in cereal crops.

Protecting spring wheat plants using selenium and pesticides.

The research was carried out in order to find ways to optimize the system of protection of spring wheat crops. In the conducted studies, the effect of combinations of sodium selenite and various pesticides, differing in the specifics of action and biological activity, on the yield and quality of spring wheat of the Yubileinaya 80 variety was studied. Currently, there is a need to achieve a sufficient effect of the action of chemical plant protection products and to obtain a minimum impact on human health and the environment. The purpose of the research is to study the influence of various combinations of chemical plant protection products and methods of using sodium selenite on the yield and grain quality indicators of spring wheat variety Yubileinaya 80. The studies were carried out under the conditions of a vegetative experiment with spring wheat variety Yubileinaya 80. Two methods of using sodium selenite and chemical plant protection agents of different specifics of action were studied: fungicide, herbicide, and insecticide, which were applied in different combinations and at different times. As a result of the studies, the phytotoxicity of the studied preparations of chemical plant protection was revealed, which apparently manifests itself as a result of inhibition of the morphometric indicators of the growth of the root system and vegetative organs of wheat plants, resulting in a violation of the processes of accumulation of assimilates and their outflow to the reproductive organs. Optimal combinations of pesticides and sodium selenite have been established, allowing to obtain reliable changes in yield and quality indicators of wheat grain. It was revealed that the use of selenium treatment before sowing seeds contributed to a decrease in the phytotoxicity of the studied pesticides, as a result of stimulating the processes of absorption by plants and the redistribution of nitrogen to the reproductive organs of wheat, which had a positive effect not only on the yield and quality of spring wheat of the Yubileynaya 80 variety, but also on the external surface microstructure of the fruit shell of the grain. The noted features of the surface of the fruit shell of the grain will reduce losses during grain processing and obtain processed products from such grain of higher quality.

Grain Yield, Biomass Accumulation, and Leaf Photosynthetic Characteristics of Rice under Combined Salinity-Drought Stress

Simultaneous stresses of salinity and drought often coincide during rice-growing seasons in saline lands, primarily due to insufficient water resources and inadequate irrigation facilities. Consequently, combined salinity-drought stress poses a major threat to rice production. In this study, two salinity levels (NS, non-salinity; HS, high salinity) along with three drought treatments (CC, control condition; DJ, drought stress imposed at jointing; DH, drought stress imposed at heading) were performed to investigate their combined influences on leaf photosynthetic characteristics, biomass accumulation, and rice yield formation. Salinity, drought, and their combination led to a shortened growth period from heading to maturity, resulting in a reduced overall growth duration. Grain yield was reduced under both salinity and drought stress, with a more substantial reduction under the combined salinity-drought stress. The combined stress imposed at heading caused greater yield losses in rice compared with the stress imposed at jointing. Additionally, the combined salinity-drought stress induced greater decreases in shoot biomass accumulation from heading to maturity, as well as in shoot biomass and nonstructural carbohydrate (NSC) content in the stem at heading and maturity. However, it increased the harvest index and NSC remobilization reserve. Salinity and drought reduced the leaf area index and SPAD value of flag leaves and weakened the leaf photosynthetic characteristics as indicated by lower photosynthetic rates, transpiration rates, and stomatal conductance. These reductions were more pronounced under the combined stress. Salinity, drought, and especially their combination, decreased the activities of ascorbate peroxidase, catalase, and superoxide dismutase, while increasing the contents of malondialdehyde, hydrogen peroxide, and superoxide radical. Our results indicated a more significant yield loss in rice when subjected to combined salinity-drought stress. The individual and combined stresses of salinity and drought diminished antioxidant enzyme activities, inhibited leaf photosynthetic functions, accelerated leaf senescence, and subsequently lowered assimilate accumulation and grain yield.

Improving Photosynthesis and Grain Yield in Wheat through Ridge–Furrow Ratio Optimization

The ridge–furrow planting pattern is an effective strategy to improve grain yield, and changes in the ridge and furrow microenvironments affect wheat yield. However, the mechanism by which wheat yields are increased at different ridge–furrow ratios is unclear. In this study, four planting modes, namely the traditional planting mode (M1) and ridge–furrow ratios of 50:50 cm (M2), 75:50 cm (M3), and 100:50 cm (M4), were established for wheat under field conditions from 2021 to 2023; the effects of different treatments on light energy utilization, dry matter accumulation and transport, and grain yield were studied. The findings demonstrated that the M3 treatment exhibited the highest enhancements in parameters such as leaf area index (LAI), canopy photosynthetically effective radiation interception rate, relative chlorophyll content (SPAD) index, and net photosynthetic rate. Moreover, the M3 treatment displayed superior grain filling compared to other treatments. The post-anthesis assimilate accumulation in the M3 treatment was 11.93%, 4.69%, and 13.13% higher than that of M1, M2, and M4 treatments, respectively, and the grain yield in M3 increased by 7.70–9.56%, 3.13–4.91%, and 8.69–10.90% compared with those in M1, M2, and M4 in the two growing seasons, respectively. In summary, under the conditions of this study, the M3 treatment led to higher LAI and SPAD values in flag leaves post-anthesis compared to the other treatments. Moreover, M3 optimized canopy structure, led to the highest canopy interception rate, and increased photosynthetic rates per individual plant. Consequently, there was a significant increase in post-anthesis dry matter accumulation, resulting in the highest grain yield achieved among the treatments.

Diurnal Regulation of Leaf Photosynthesis Is Related to Leaf-Age-Dependent Changes in Assimilate Accumulation in Camellia oleifera.

In order to clarify the mechanism of diurnal changes in photosynthesis of leaves of different leaf ages in Camellia oleifera, current-year leaves (CLs) and annual leaves (ALs) were used as the test materials to analyze the diurnal changes in photosynthetic parameters, assimilate contents and enzyme activities, as well as structural differences and expression levels of sugar transport regulating genes. The rate of net photosynthesis in CLs and ALs was highest in the morning. During the day, there was a decrease in the CO2 assimilation rate, and this decrease was greater in ALs than in CLs at midday. The maximal efficiency of photosystem II (PSII) photochemistry (Fv/Fm) showed a decreasing trend as the sunlight intensity increased, but no significant difference between CLs and ALs was found. Compared with CLs, ALs showed a greater decrease in the carbon export rate at midday and the levels of sugars and starch increased significantly in ALs, accompanied by higher enzyme activity of sucrose synthetase and ADP-glucose pyrophosphorylase. In addition, compared with CLs, ALs had a larger leaf vein area and higher leaf vein density, as well as higher expression levels of sugar transport regulating genes during the day. It is concluded that the excessive accumulation of assimilate is an important factor contributing to the midday depression of photosynthesis in Camellia oleifera annual leaves on a sunny day. Sugar transporters may play an important regulatory role in excessive accumulation of assimilate in leaves.

Eco-physiological response of secondary metabolites of teas: Review of quality attributes of herbal tea

Herbal tea is a rich source of secondary metabolites which are reputed to have medicinal and nutritional efficacy. These secondary metabolites are influenced by the abiotic and biotic stresses that improve the production of herbal teas in terms of biomass production, accumulation and partitioning of assimilates of compounds. In this study, various examples of herbal teas have been shown to respond differently to secondary metabolites affected by environmental factors. Thus, the meta-analysis of this study confirms that different herbal teas' response to environmental factors depends on the type of species, cultivar, and the degree of shade that the plant is exposed. It is also evident that the metabolic processes are also known to optimize the production of secondary metabolites which can thus be achieved by manipulating agronomic practices on herbal teas. The different phenolic compound in herbal teas possesses the antioxidant, antimicrobial, antiatherosclerosis, anti-inflammatory, antimutagenic, antitumor, antidiabetic and antiviral activities that are important in managing chronic diseases associated with lifestyle. It can be precluded that more studies should be conducted to establish interactive responses of biotic and abiotic environmental factors on quality attributes of herbal teas.

Effects of nitrogen application rate on the accumulation of 13C assimilates after flowering and water-nitrogen use efficiency of wheat under supplemental irrigation based on soil moisture.

This study aimed to explore nitrogen fertilizer management measures to synergistically improve wheat yields and water and nitrogen use efficiency under supplemental irrigation based on soil moisture in the Huang Huai winter wheat area. Wheat variety "Yannong 1212" was used as the test material. There were three nitrogen application levels, 150 kg·hm-2 (N1), 210 kg·hm-2 (N2), and 270 kg·hm-2 (the conventional nitrogen application rate in the Huang Huai winter wheat area, N3), with the relative soil water content of 0-40 cm of each treatment was supplemented to 70% at the jointing and flowering stages. We investigated the effects of nitrogen rates on photosynthetic characteristics of flag leaves after flowering, 13C assimilate accumulation and transport, and water and nitrogen use efficiency after flowering of wheat. The results showed that photosynthetic capacity of flag leaves in the N2 and N3 was significantly higher than that in N1 14-35 days after flowering, and that there was no significant diffe-rence between N2 and N3 treatments. The 13C isotope tracing results showed that the translocation amount of 13C assimilates in vegetative organs in N2 was 12.1% and 7.1% higher than that in N1 and N3, respectively. The distribution amount of 13C assimilates in grains at maturity was 10.1% and 5.3% higher than that of N1 and N3, respectively. The amount of nitrogen fertilizer affected water consumption, water consumption proportion, and total water consumption in different growth stages of wheat. Water consumption during the whole growth period showed no difference between N2 and N3 treatments, but both were significantly higher than that for N1. Water consumption and water consumption proportion of N2 were higher from the jointing to maturity stages, water use efficiency of N2 was 7.5% and 4.8%, and grain yield was 4.7% and 10.9% higher than that of N3 and N1 treatments, respectively. The partial productivity of nitrogen fertilizer was 34.6% higher in the N2 than that of N3. Considering wheat grain yield and water and nitrogen use efficiency, 210 kg·hm-2 nitrogen application was the best rate under water-saving condition of supplementary irrigation after soil moisture measurement in the study area.

Adubação orgânica e estresse salino no desempenho agronômico da cultura do milho

ABSTRACT Irrigation water salinity can cause serious problems in crop production, while organic fertilizer sources potentially mitigate saline stress. Thus, this study aimed to evaluate the productivity of maize crops under irrigation with saline water and organic fertilization. The study was conducted in the field from August to November 2020 at the experimental farm of the Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), Redenção-CE. A randomized block design was used, in subdivided plots, in which the plots consisted of two levels of irrigation water salinity (0.8 and 3.0 dS m-1). Four combinations of organic fertilizer sources were applied in the subplots, composed of 10 plants each, with four replications: C1, cattle manure + poultry biofertilizer + goat biofertilizer; C2, cattle manure + goat biofertilizer; C3, cattle manure + poultry biofertilizer; and C4, control treatment. The combination of organic fertilizer sources did not influence the accumulation of assimilates and productivity of maize crops under the irrigation water salinity of 3.0 dS m-1, except for C3, which attenuated the saline effect.

Effect of Nitrogen Application on Root and Yield Traits of Chinese Spring Wheat (Triticum aestivum L.) under Drip Irrigation

To clarify the regulatory effects of different N fertilizer treatments on the root morphology, physiological characteristics, and assimilate accumulation of drip-irrigated spring wheat under the northern border climate, we used strong wheat Xinchun 38 (cv. XC 38) and medium gluten wheat Xinchun 49 (cv. XC 49) as test materials in 2019 and 2020, and cultivated them in soil columns at Nck (300 kg·ha−1), A1 (240 kg·ha−1), A2 (210 kg·ha−1), and N0 (0 kg·ha−1). We also studied the effects of N application on root morphological characteristics, key enzymes of N metabolism, antioxidant enzymes, dry matter accumulation distribution, and yield of drip-irrigated wheat. The results showed that the root morphological characteristics, key enzymes of nitrogen metabolism, antioxidant enzymes, shoot dry matter accumulation, spike dry matter, and yield all showed an increasing and then decreasing trend with increasing nitrogen application. Among them, A1 treatment showed the best root length density (RLD), root volume density (RVD), root mass density (RMD), nitrate reductase (NR), glutamine synthetase (GS), glutamate synthetase (GOGAT), glutamic-pyruvic transaminase (GPT), superoxide dismutase (SOD), peroxidase (POD), root activity, shoot dry matter accumulation, spike dry matter, and yield, which were significantly higher than other treatments. The malondialdehyde (MDA) content decreased by 3.36–15.70% compared with other treatments. Correlation analysis showed that yields were positively correlated with RLD, RVD, RMD, GS, and GPT and negatively correlated with MDA. Nitrogen treatments and varietal intercropping had significant effects on RLD, root activity, NR, GS, GPT, POD, and yield. Therefore, moderate N reduction (240 kg·ha−1) under the drip irrigation pattern in Xinjiang can improve the morphological characteristics and physiological functions of wheat roots, promote the distribution and transport of dry matter to spikes, and facilitate yield formation.

The era of cultivating smart rice with high light efficiency and heat tolerance has come of age.

How to improve the yield of crops has always been the focus of breeding research. Due to the population growth and global climate change, the demand for food has increased sharply, which has brought great challenges to agricultural production. In order to make up for the limitation of global cultivated land area, it is necessary to further improve the output of crops. Photosynthesis is the main source of plant assimilate accumulation, which has a profound impact on the formation of its yield. This review focuses on the cultivation of high light efficiency plants, introduces the main technical means and research progress in improving the photosynthetic efficiency of plants, and discusses the main problems and difficulties faced by the cultivation of high light efficiency plants. At the same time, in view of the frequent occurrence of high-temperature disasters caused by global warming, which seriously threatened plant normal production, we reviewed the response mechanism of plants to heat stress, introduced the methods and strategies of how to cultivate heat tolerant crops, especially rice, and briefly reviewed the progress of heat tolerant research at present. Given big progress in these area, the era of cultivating smart rice with high light efficiency and heat tolerance has come of age.

Quantifying source-sink relationships of drip-fertigated potato under various water and potassium supplies

Water and fertilizer supply can affect the processes of assimilate production (source) and assimilate accumulation (sink), thereby causing differences in potato yield. However, little is known about the coupling effects of irrigation amount and potassium rate on potato tuber yield and its potential source-sink relationships. The objective of this study was to quantify how water and potassium supplies affected the source-sink relationships of drip-fertigated potato after tuber emergence. A two-year field experiment was conducted during the potato growing seasons of 2019 and 2020, with three irrigation levels (W1: 60% ET c , W2: 80% ET c and W3: 100% ET c , where ET c is the crop water requirements) and four potassium rates (K0: 0 kg ha -1 , K1: 135 kg ha -1 , K2: 270 kg ha -1 and K3: 405 kg ha -1 ). The results showed that compared with K0, the treatments viz ., K1, K2 and K3 increased average tuber yield by 1.3%, 17.3% and 15.5% in 2019 and 10.7%, 24.0% and 19.3% in 2020, respectively. However, compared with W3, the treatments viz ., W1 and W2 reduced the average tuber yield by 8.0% and 12.9% in 2019 and 8.9% and 14.7% in 2020, respectively. The beta sigmoid growth function well fitted the relationship of source capacity and sink capacity. The source capacity and source activity increased with the increase of potassium rate under W2 and W3 in 2019 and under W3 in 2020, while the sink capacity and sink activity first increased and then declined with the increasing potassium rate. Increasing water and potassium supply generally increased the vegetative growth and tuber growth time. The tuber growth rate first increased and then decreased with the increase of potassium rate, while it increased with the increasing irrigation amount. The sink-source ratio decreased with the increase of potassium rate, but there was no significant difference between K1 and K2, and the sink-source ratio under K3 was significantly lower than that in the other potassium treatments. It was concluded that potato was in source-sink balance under K1 and K2, but not under K3. The quantitative approach produced parameters that characterized the differences of source and sink capacity in response to various water and potassium supplies. Sufficient irrigation (W3) with moderate potassium application (K2) increased potato yield mainly by maintaining its source-sink balance. • A model approach was proposed to quantify source-sink relationships of potato under various water and potassium supplies. • The mechanism analysis of yield difference from various water and potassium supplies was conducted by source-sink balance. • Source-sink capacity was affected by different water and potassium management practices. • The sink-source ratio was not significantly different between 135 and 270 kg ha -1 , indicating the source-sink balance. • Various water and potassium application amounts influenced plant potassium absorption and tuber yield.

Whole-genome resequencing identified QTLs, candidate genes and Kompetitive Allele-Specific PCR markers associated with the large fruit of Atlantic Giant (Cucurbita maxima).

Atlantic Giant (AG) pumpkin (Cucurbita maxima) produces the world’s largest fruit. Elucidating the molecular mechanism of AG fruit formation is of scientific and practical importance. In this research, genome-wide resequencing of an F2 population produced by a cross between AG and its small-fruit ancestor Hubbard was used to identify quantitative trait loci (QTLs) and candidate genes. Transgressive segregation of fruit size-related traits was observed in the F2 population, suggesting that fruit size was a quantitative trait controlled by multiple genes. A genetic map with an average physical distance of 154 kb per marker was constructed, and 13 QTLs related to fruit size were identified using bin-map construction. RNA sequencing analysis revealed that pathways associated with assimilate accumulation into the fruit, including carbohydrate metabolism, were significantly enriched in differentially expressed genes. According to the predicted impact of mutation on the biological function of certain proteins, 13 genes were selected as candidate genes associated with fruit size, among which two phytohormone-related genes, CmaCh17G011340 (a flavin-containing monooxygenase) and CmaCh04G029660 (a leucine-rich repeat protein kinase) were chosen for further investigation. Finally, one insertion-deletion (inDel) and three single nucleotide polymorphisms (SNPs) were successfully transformed to Kompetitive Allele-Specific PCR (KASP) markers. The novel QTLs and candidate genes identified provide insights into the genetic mechanism of large fruit formation of AG, and the genetic map and tightly linked KASP markers developed in this study can be employed for marker-assisted breeding to alter fruit size of C. maxima.

Shade Delayed Flowering Phenology and Decreased Reproductive Growth of Medicago sativa L.

Alfalfa (Medicago sativa L.) is an important forage in intercropping or rotation ecosystem, and shading is the principal limiting factor for its growth under the crop or forest. Agronomic studies showed that shading would systematically reduce the biomass of alfalfa. However, little is known about the reproduction of alfalfa under shading conditions. In order to study the effect of shading on the reproductive characteristics of alfalfa, two alfalfa cultivars (“Victoria” and “Eureka”) were used to study the effect of shading levels (full light, 56.4% shade, and 78.7% shade) on alfalfa flowering phenology, pollen viability, stigma receptivity, and seed quality. Results showed that shading delayed flowering phenology, shortened the flowering stage, faded the flower colors, and significantly reduced pollen viability, stigma receptivity, the number of flowers, quantity, and quality of seeds. Under shading conditions, seed yield per plant was obviously positively correlated with germination potential, germination rate, pollen viability, and 1,000-seed weight. The number of flower buds, pollen viability, 1,000-seed weight, and germination rate had the greatest positive direct impact on seed yield per plant. Our findings suggested that delayed flowering and reducing reproduction growth were important strategies for alfalfa to cope with shading and pollen viability was the key bottleneck for the success of alfalfa reproduction under shading. However, given that alfalfa is a perennial vegetative-harvest forage, delaying flowering in a weak light environment was beneficial to maintain the high aboveground biomass of alfalfa. Therefore, this should be taken into account when breeding alfalfa cultivars suitable for intercropping. Future research should further reveal the genetic and molecular mechanism of delayed flowering regulating the accumulation and distribution of assimilates between vegetative and reproductive organs of alfalfa under shading, so as to provide a theoretical basis for breeding of shade-tolerant alfalfa cultivars.