For direct-seeded cotton production following wheat or rapeseed harvested in the Yangtze River Basin, competition of space and nutrients from regenerated seedlings of previous crops (they are weeds actually here) hinders cotton seedlings'growth. This study aims to elucidate the mechanisms of potential removal of the constrain by modifying a commercialized seed coating agent with different exogenous substances (potassium dihydrogen phosphate (PDP), glucose (Glc), and diethyl aminoethyl hexanoate (DA-6)). Treatments included a water control (CK), a basic seed coating agent (BSC), and BSC supplemented with graded levels of PDP (1-8 g L-1 ), Glc (1.6-6.4 g L-1 ), or DA-6 (5-320 mg L-1 ). Effects on seed emergence, seedling growth, photosynthetic traits, and leaf anatomy were assessed through indoor, pot, and field experiments. Results indicated that 4 g L-1 PDP (PDP3) and 1.6 g L-1 Glc (Glc1) were more effective than other treatments, though no synergistic effects occurred when combined. PDP3 markedly improved seed emergence (93.33 %) and enhanced seedling leaf area, height, and biomass. It maintained auxin homeostasis by suppressing IAA oxidase (IAAO) activity, promoted upper epidermal cell expansion, and differentially regulated stomatal distribution, significantly increasing stomatal density on the upper epidermis by 37.0 % while decreasing it on the lower epidermis. PDP3 also elevated pigment content, ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity, and net photosynthetic rate (13.70 % higher than CK), resulting in greater accumulation of soluble sugars and sucrose. Field trials further showed that PDP3-treated cotton sustained larger leaf area and higher photosynthetic efficiency in later stages, increasing seed cotton and fiber yields by 18.00 % and 24.00 %, respectively. These findings demonstrate that the modified coating agent, especially PDP3, promotes vigorous seedling establishment by orchestrating a coordinated physiological program involving auxin homeostasis, optimized stomatal anatomy, and enhanced photosynthetic capacity, thereby providing a novel strategy to overcome the early competition bottleneck in direct-seeded cotton systems.

Nitrogen (N) management is crucial for sustaining crop yield, improving profitability, and ensuring environmental stewardship. Multiple soil N application is facing quite a few challenges, especially when the canopy is closing, such as low efficiencies in both N use and application, disturbance or even drop of the plant fruits during application. We suppose that N foliar spraying could be a potential candidate to partially replace soil application. Therefore, the aim of this study was to verify if the foliar N application could improve cotton yield, and its possible mechanisms in N absorption, root architecture and root-shoot relationship. A 2-season (2020-2021) field experiment with a randomized complete block design was conducted to evaluate the effects of foliar N spraying on cotton yield and its components, root development, biomass accumulation and N uptake, in comparison with the multiple soil application and the conventional farmers practice as well. The results showed that multiple soil and foliar N application at flowering period improved cotton yield over the conventional N managements, while a similar performance was observed between soil and foliar strategies. Further, foliar N spraying increased shoot biomass partitioning, establishing an allometric root-shoot relationship that ultimately resulted in a 5.3 % increase in total N uptake. Meanwhile, foliar N application reduced root allocation in the topsoil while promoting deeper root development, which confirmed as a critical factor for yield improvement by SHapley Additive exPlanations (SHAP) analysis. Overall, split foliar N application increased cotton yield by higher shoot partitioning, combined with a deeper and thinner root architecture, thereby alleviating leaf senescence. These findings highlighted the potential of foliar nitrogen strategies to support mechanised cotton production by improving nitrogen use efficiency and production sustainability, particularly in regions where soil-based fertilisation is constrained by climatic or management limitations like semi-arid regions.

Tinospora sagittata (Oliv.) Gagnep. is an essential medicinal tetraploid plant in the Menispermaceae family. Its tuber, “Radix Tinosporae,” is widely used in Traditional Chinese Medicine and is rich in terpenoids and benzylisoquinoline alkaloids (BIAs). To better understand the biosynthesis of these compounds and the evolution of the T. sagittata genome, we performed comparative genomics with 16 other plant species, estimating its evolutionary placement and divergence time within Ranunculales. Genome evolution analyses revealed one round of tandem duplication approximately 1.5 million years ago and one whole-genome duplication (WGD) around 86.9 Mya. WGD contributed to the expansion of the clade-specific cytochrome P450 gene families in Ranunculales. Genome-wide mining identified genes involved in BIA biosynthesis, and transcriptomic profiling was combined with targeted and untargeted metabolomics to analyze gene expression and metabolite accumulation. Finally, one CYP719 gene candidate (TsA02G014550) was functionally characterized to catalyze the formation of (S)-canadine in the jatrorrhizine biosynthetic pathway. Our integrative genomics, transcriptomics, and metabolomics analyses provide new insights into the evolution of the T. sagittata genome and BIA biosynthesis, supporting future sustainable production of these valuable secondary metabolites.

Nitrogen (N) deficiency is considered one of the key factors limiting cotton growth and productivity. Kinetic and root morphological parameters influencing nutrient absorption efficiency are often overlooked in crop breeding programs. This hydroponic study examined the growth, morphology, and uptake kinetics parameters including maximum absorption velocity (Vmax), Michaelis-Menten constant (Km), minimum concentration (Cmin) for NO3- and NH4+ in cotton varieties, N-efficient Ghotki-Uhad (GH-Uhad) and N-inefficient Faisalabad-Hybrid (FH-444) subjected to 0.5 and 5 mM N supply. The studied parameters considerably responded to N application either in the form of NO3- or NH4+. High-N treatment significantly increased shoot dry weight (SDW) (46.7%), root dry weight (RDW) (28.3%), and total biomass (42.7%) compared to low-N and results were more obvious (16% higher biomass) under NO3--N than NH4+-N. Compared to NH4+-N, root length (RL) and root surface area (RSA) increased under low NO3--N while high NO3--N improved mean root diameter and root volume. Furthermore, GH-Uhad had low Km and Cmin for both N forms, suggesting that it functioned in a high-affinity transport system (HATS) under low N-supply. Contrarily, FH-444 exhibited higher Vmax for NH4+ but had low affinity irrespective of N forms. However, GH-Uhad preferred NO3- over NH4+, while FH-444 switched between the two at low and high N levels. Root morphological traits, Vmax, Cmin, and N content were positively associated with growth attributes while kinetic parameters had a negative correlation with root morphological traits. In crux, GH-Uhad performed better for growth, root morphology, and exhibited high affinity for N uptake, showing its adaptation to N-limited conditions.

Cotton, as a globally important economic crop, has high nitrogen (N) demand but low N uptake and N utilization efficiency (NUE). Optimizing N input by improving NUE represents a critical challenge for sustainable cotton production. We applied six N levels (0, 0.04, 0.4, 1, 4, 8mM Ca(NO3 )2 , designated as N0, N0.04, N0.4, N1, N4, and N8, respectively) to examine their effects on morphology, biomass, nutrient absorption, and NUE at four treatment durations. Results showed that seedling growth and nutrient accumulation initially increased and subsequently decreased with increasing N levels. The optimal N ranges for seedling growth at 7, 14, 21 and 28d were 0.4, 0.4-1, 1-4 and 4-8mM Ca(NO3 )2 , respectively. Under optimal N, seedlings achieved maximum accumulations of N, P, K, and Ca (55.8, 8.8, 64.9, and 26.2mg/plant at 28d, respectively), while maintaining consistent N:P:K:Ca ratios of approximately 1:0.2:1.2:0.5 across seedling stage. Under low N, nutrients were preferentially allocated to roots, promoting root growth. NUE exhibited positive correlations with root traits and nutrient proportion, whereas shoot traits showed positive associations with nutrient accumulation and shoot nutrient proportion. These findings provide a theoretical basis for scientific fertilization, and establish a theoretical foundation for understanding the physiological mechanisms of efficient N use in cotton.

Low nitrogen (N) is a major limitation of cotton sustainability and productivity. N-efficient genotype cultivation can enhance productivity under the economical N usage. This study was conducted to characterize 15 cotton genotypes for N use efficiency (NUE) under differential N (0.0125 and 0.125 g kg-1 of sand) supply. All studied traits significantly responded to genotypes and N treatments. Under low N conditions, plants experienced reduced seedling height, root weight, shoot weight and total biomass (TDM) production, chlorophyll content, photosynthetic efficiency, NPK content, and N uptake efficiency (NUpE). Thus, intercellular CO2 concentration, photosynthetic N use efficiency (PNUE), and NUtE enhanced in low N supply, although these changes varied in magnitude. Based on variations in TDM production (14.6-33.1%) and NUtE (3.3-20.4%), GH-Uhad, FH-Anmol, FH-Super, GH-Haadi, and SLH-Chandani were categorized as efficient and responsive (ER), while J-7, CIM-343, FH-155, FH-492, FH-444 found as inefficient and non-responsive. The efficient and non-responsive group contained FH-142, GH-Baghdadi, and FH-490 whereas FH-152 and Cyto-179 were classified as inefficient and responsive. The scoring method provided further insight into genotypic NUE related to biomass distribution, photosynthetic rate (Pn), NUpE, and NUtE under low N. The highest cumulative score (15-18) of ER genotypes for these attributes indicated selected traits orchestrated to determine the NUE. Moreover, agronomical and NUE-related traits were positively associated with Pn, suggesting that photosynthesis is a primary manipulator of plant growth which coordinates biomass production and NUE. Overall, cultivars exhibited greater genotypic variation for NUE, providing a scientific basis to evaluate the existing germplasm and proposing that cultivation of N-efficient genotypes can decrease N application and help cotton breeding for sustainable production.

Medicinal plants are vital in synthesizing crucial substrates, fortifying stress resilience, and serving clinical and industrial domains. The optimization of pharmacological potential necessitates a nuanced understanding of the factors governing the synthesis of secondary metabolites sourced from plants. Cultivation success hinges upon many factors dictating the production of these vital compounds. Biotic factors, encompassing pathogens and herbivores, alongside abiotic factors such as light exposure, altitude, temperature variations, irrigation patterns, soil fertility, drought susceptibility, and salinity levels, collectively orchestrate medicinal plants' growth, development, and metabolic pathways. This comprehensive review delves into the intricate interplay of factors influencing the formation of secondary metabolites, exploring the roles of endophytes, pathogens, light availability, temperature fluctuations, drought stress, pollution impacts, and plant growth regulators. Grasping the dynamics of these factors is imperative for devising strategic interventions to enhance secondary metabolite production, thereby ensuring the sustainable and efficient cultivation of medicinal plants.

Tinospora sagittata (Oliv.) Gagnep. is an important medicinal tetraploid plant in the Menispermaceae family. Its tuber, Radix Tinosporae, used in traditional Chinese medicine, is rich in diterpenoids and benzylisoquinoline alkaloids (BIAs). To enhance our understanding of medicinal compounds’ biosynthesis and Menispermaceae’s evolution, we herein report assembling a high-quality chromosome-scale genome with both PacBio HiFi and Illumina sequencing technologies. PacBio Sequel II generated 2.5 million circular consensus sequencing (CCS) reads, and a hybrid assembly strategy with Illumina sequencing resulted in 4483 contigs. The assembled genome size was 2.33 Gb, consisting of 4070 scaffolds (N50 = 42.06 Mb), of which 92.05% were assigned to 26 pseudochromosomes. T. sagittata’s chromosomal-scale genome assembly, the first species in Menispermaceae, aids Menispermaceae evolution and T. sagittata’s secondary metabolites biosynthesis understanding.

Tinospora sagittata is rich in secondary metabolites used in traditional medicine. However, environmental factors impact key enzymes in metabolite synthesis, highlighting the need for improved growth conditions. This study employs transcriptomics and metabolomics to assess nitrogen's impact on enzymes in secondary metabolites biosynthesis pathways. The gene expressions of berberine bridge enzymes (BBEs) like TsBBE2 had peak expression in low nitrogen treatments (A0 and A1) but were absent in higher nitrogen treatments (A2 and A3). Similar trends were observed for other enzymes such as (S)-scoulerine 9-O-methyltransferase (TsCMT3), Tetrahydroberberine oxidase (TsSTOX), and Columbamine O-methyltransferase (TsCoCOMT2-4) in response to nitrogen levels. In examining gene families related to diterpene synthases (diTPS), 1-deoxyxylulose 5-phosphate synthase (TsDXR1) expression increased with higher nitrogen fertilizer, while TsDXR2 peaked at maximal nitrogen levels. Geranylgeranyl diphosphate synthase (TsGGPP3 and TsGGPP5) decreased with nitrogen levels. (-)-kolavenyl diphosphate synthase (KPS) genes had higher expression in treatments, while ent-kaurene synthase (KSL) genes, especially TsKSL1 and TsKSL2, showed higher expression in control conditions with lower nitrogen fertilizer. Metabolite analysis confirmed more upregulated compounds in A3 compared to A0. These findings have practical implications for agriculture and pharmaceuticals, highlighting the link between nitrogen fertilization and specialized metabolism in medicinal plants.

Multiple nitrogen (N) application is proved to increase cotton yield, while whether foliar spraying can replace soil application remains unclear, although foliar application may be easier to carry out and probably more efficient than that of the conventional soil application method under mechanical system. A field experiment was conducted in 2020 and 2021, with eight N managements including three N frequency treatments for both soil and foliar application, with a comparison to two controls treatments to investigate cotton radiation and water use efficiency, and the subsequent yield. Results showed that, averaged across years, twice foliar N applications achieved the highest value in seedcotton and lint yield with no difference from the soil applying but higher than each of the two controls. Those yield advantages were attributed to higher gas exchanges attributes in foliar N application treatments, which were 5.2% and 15.6% higher in net photosynthetic rate, and 14.9% and 32.8% higher in stomatal conductance than soil application and CK treatments in two years averaged, respectively. Meanwhile, N foliar spraying decreased canopy light transmittance at boll opening stage by 9.6–15.1% and increased maximal canopy light interception by 2.6–5.0% and the duration of canopy light interception (CLI) >70% by 0.9–1.5 d compared with that of soil applied and the controls, showing an improved radiation use efficiency which contributed directly to cotton yield (r = 0.78). Optimal cotton yield was achieved at foliar N application in two times, and this yield advantages was attributed from the synergistic increase in efficient radiation and leaf water utilization. Thus, foliar spraying can replace soil N topdressing to realize efficient yield formation in late sown cotton production system in the Yangtze River Valley, China, and areas with similar ecology.

Sustainable cotton production has been an everlasting challenge due to multiple measures. An innovative cotton cropping system characterized by late sowing, once fertilization and higher density has been successfully practiced in China. But, it is still unsure that mepiquat chloride (MC) application is an essential input in this cropping model or not. We hypothesized that MC application might reduce the cotton growth and yield and thus can be ignored to increase the net farm income. To test this hypothesis, a 2-year field experiment was performed where cotton was sown in late-May at 10 plants m−2 planting density and with 225 kg N ha−1 single fertilization. Foliar application of MC was done thrice with 5 leaf intervals which were initiated from the 6th leaf stage in 5 dosages (0, 30, 60, 90, and 120 g ha−1). Cotton growth attributes including leaf area index and leaf area duration were drastically reduced and control treatments (MC0) showed maximum increase by 28–35

Double direct seeding of cotton (with wheat or rapeseed) is a new method for cotton-growing regions in the Yangtze River Basin to adapt to the development of mechanization. It would help to reduce manual labor, optimize the amount of nitrogen fertilizer to be used, reduce the physical and chemical production costs, and improve the benefits of cotton fields. We selected five counties from the major cotton-producing areas of Hubei Province for three consecutive seasons, from winter 2020 to spring 2022. The experimental sites used no tillage with straw returning to the field, double direct seeding, late sowing at high density, and one-time fertilization to study the effects of different nitrogen fertilizer rates on the yield characteristics of cotton, wheat, and rape and calculate the economic benefits of the two cultivation modes under different nitrogen fertilizer input levels through parameters such as land-use efficiency, production efficiency, and profitability. In both cotton–wheat and cotton–rapeseed cropping systems, the number of bolls per plant in cotton was the lowest in the N165 (90 cotton + 75 wheat/rape kg ha−1) treatment. The cotton yield was the highest at N247.5 (135 cotton + 112.5 wheat/rape kg ha−1) in the cotton after the wheat system and N412.5 (225 cotton + 187.5 wheat/rape kg ha−1) in the cotton after the rape system. The yield of wheat and rape increased with the increase in the levels of nitrogen fertilizer, with the N165 treatment showing the lowest values. With an increase in nitrogen fertilizer, the harvest index of wheat first maximized and then started decreasing. The harvest index in wheat was the highest at N247.5 (135 cotton + 112.5 wheat/rape kg ha−1) and N330 (180 cotton + 150 wheat/rape kg ha−1), whereas, in rape, it increased with nitrogen fertilizer application, with the highest value at N495 (270 cotton + 225 wheat/rape kg ha−1). Economically, the expenses and income of both cotton–wheat and cotton–rape systems increased as nitrogen fertilizer increased. The net profit and benefit ratio first increased and then decreased with increasing nitrogen fertilizer, with N247.5 (135 cotton + 112.5 wheat/rape kg ha−1) scoring the maximum values for both of these parameters. The land-use efficiency and production efficiency increased with the increase in nitrogen fertilizer, and the production efficiency of the N165 (90 cotton + 75 wheat/rape) treatment was significantly lower than that of the other four treatments. The profitability increased first and then decreased with the increase in nitrogen fertilizer, with the N247.5 (135 cotton + 112.5 wheat/rape) treatment showing the highest profit. The production cycle of cotton–rape was slightly shorter than that of cotton–wheat, and the system productivity was also lower. The expenses and land-use and production efficiency of the rapeseed system were lower than those of wheat, while the gross income, net profit, and productivity of the cotton–rape system were higher than those of cotton–wheat. The application of nitrogen fertilizer in the cotton–wheat double-cropping system under straw return can achieve the maximum net profit, production ratio, and yield at the low nitrogen level of N247.5, (135 cotton + 112.5 wheat/rape kg ha−1). Due to the price advantage of rape, the net profit, production ratio, and income of the cotton–rape production system are higher than those of the cotton–wheat production system.

Context: Nitrogen (N) loss is becoming one of the main limitations for sustainable agricultural production globally, particularly for crops such as cotton. Research question: To alleviate this issue, a promising strategy may be to exploit the N-saving potential of cotton plants by optimizing N application ratios at different growth stages under lower N rate and higher planting density with wide-row spacing. Methods: Two field experiments were carried out to investigate cotton yield, N use efficiency (NUE), N accumulation characteristics, and N-15 uptake and distribution in response to N fertilization. First, a two-year experiment was conducted with N fertilization of either 0, 120, 240, 360 (control) or 480 kg ha(-1). A three-year experiment was then carried out with 240 kg N ha(-1) being applied with different ratios across three periods (squaring, flowering to peak boll, and late peak boll), i.e., 0:6:4 (N-064), 1:6:3 (N-163), 2:6:2 (N-262, control), 3:6:1 (N-361) and 4:6:0 (N-460). Results: Compared with conventional N fertilization (360 kg N ha(-1)), moderate fertilization at 240 kg N ha(-1) resulted in steady and higher seed cotton yields of 5945 and 5603 kg ha(-1) in 2017 and 2018, respectively, and improved NUE by 49.1-53.6%. Compared with conventional N-262, a shift to later N application (N-064) increased both lint yield and partial factor fiber productivity of nitrogen (PFFPN) by 4.4-7.7%, and accumulated 6.1-14.4% more total N (K) in reproductive organs due to higher average (Vt) and maximum (Vm) accumulation rates by 25.2-49.0% and 15.0-48.7%, respectively, while the fast N accumulation period (Delta t) shortened by 15.2-24.4%. N-064 partitioned 15.6% more N-15 to reproductive organs. NUE was significantly positively correlated with K, t(1) (the day when Delta t started), Vt, Vm, Tm (the day on which Vm occurred) and N-15 accumulation in middle and upper canopy bolls, and negatively correlated with Delta t of total N accumulation in reproductive organs. Conclusions: Allocating N from the squaring period to the late peak boll period led to an increase in N uptake during the reproductive growth stage and greater allocation of N to cotton bolls under reduced-N cultivation and drip fertigation. Significance: This N management strategy is a potential way to improve NUE and achieve sustainable and efficient production of cotton in arid areas.

Nitrogen (N) is an essential plant macro-nutrient for crop sustainability and productivity. Substantial quantities of N fertilizers are being applied in soil, but only about 33% is utilized by the plants. Its availability in soil varies to a great extent in terms of time and space. Plant root systems should efficiently respond to fluctuating N by tailoring root growth and development. However, N fertilizer production consumes massive energy resource, and excessive application has negative consequences on the environment and human health. Therefore, innovative solutions are imperative to enhance crop yields and N use efficiency (NUE) simultaneously, while maintaining and/or reducing N application amount. Crop NUE is a complex attribute, because it is controlled by numerous genetic as well as environmental factors interact to govern the mechanisms involved in N sensing, uptake, translocation, assimilation, and remobilization in plants. Hence, a better understanding of these mechanisms is a key factor for improving NUE in cropping systems. In this review, we discussed the molecular, biochemical, and enzymatic mechanisms involved in NUE in crop plants, ways to increase NUE through the identification of plant factors with special consideration of their interaction, and different management strategies. In addition, adaptation of classical approaches, i.e., root architecture studies, quantitative trait loci (QTLs), and selection of genes for better NUE, are briefly discussed. Broadly, from root uptake to accumulation of N assimilates in various plant tissues, an array of physiological mechanisms is involved which is still not fully understood. Moreover, employing an integrated approach by combining expertise from fundamental and applied investigations in crop sciences may add further to available knowledge regarding crop N utilization.

Context: Conventional relay intercropping of cotton in wheat is being replaced by late-sown cotton after wheat to increase wheat output and decrease labor and nitrogen (N) input of cotton with no yield reduction in Yangtze River Valley of China. Objective: However, the mechanistic basis for yield stabilization in a higher plant density with decreased N rate of late-sown cotton from the perspective of light interception and N partitioning has not been evaluated. Methods: A split plot experiment with two planting densities (D1, 6 plants m- 2; D2, 8 plants m-2) as the main plot and three N rates (N1, 150 kg ha -1; N2, 180 kg ha -1; N3, 210 kg ha -1) as the subplot was conducted in Wuhan from 2018 to 2019 to determine their interaction on cotton yield, canopy light interception (CLI), temperatures and humidity, and N partitioning in different sections of the plant. Results: Results showed that a significant interaction of plant density and N rate existed, which indicated that at 8 plants m- 2, N rate could be reduced to 180 kg ha- 1 without yield reduction compared with 210 kg ha -1. CLI at peak bloom stage, the maximal light interception, and the duration of CLI > 70% were increased by 30.1%, 3.5%, and 9.4% at 8 plants m- 2 compared with those at 6 plants m- 2, respectively. However, a lower maximal canopy temperature and relative humidity at flowering under 8 plants m- 2 compared to 6 plants m- 2 was recorded, showing a negative correlation with cotton yield (P<0.05). Cotton had 14.9% and 2.8% higher N uptake and sink N partitioning at 8 plants m- 2 compared to those at 6 plants m- 2, respectively. Thus, N use efficiency at 8 plants m- 2 was increased. Conclusions: A reduction in the rate of N at high plant density increased CLI and sink N partitioning and thus did not reduce yield in late-sown cotton. Implications: Therefore, the optimal seedcotton yield was achieved at 8 plants m- 2 combined with 180 kg N ha -1, which attributed to higher canopy light interception and N utilization in late-sown cotton after wheat harvest.

A new competitive and cost-effective planting model specified with late-sowing, high-density and reduced-nitrogen (N) rate with once-fertilization is a potential alternate to the conventional high-cost cotton cropping system. In this model, as the N rate is reduced, a question remains as to what the optimal K application rate should be due to its significant role in cotton physiology and yield formation. So, three K rates: K-1 = 168 K2O kg ha(-1), K-2 = 210 K2O kg ha(-1), and K-3 = 252 K2O kg ha(-1) under reduced N rate (210 N kg ha(-1)) with four replications were used to quantify the effect on leaf C/N ratio, amino acid pools, and yield of cotton during 2016 and 2017. The results exhibited that higher K rates (K-2 and K-3) considerably lowered leaf C/N ratio and amino acid pools while enhancing the lint yield and seed cotton yield in both growing seasons. Enhanced leaf K level resulted in reduced amino acid pools and low leaf C/N ratio. The increase in boll weight with increased leaf K and decreased leaf C/N ratio improved the yield. Results further directed that a higher K rate rationally balanced the C/N ratio and amino acid pools to a low range in cotton leaf. However, from economic view point, K rate equal to N is appropriate to get satisfactory yield in late-sown cotton with high-density.

Potassium (K) is an essential and critical determinant of plant physiological and biochemical processes. Despite the fact, this nutrient is depleted or imbalanced due to intensive cropping and the problem is more serious in cotton-wheat or cotton-rapeseed cropping systems. To find out whether potassium application under reduced nitrogen (N) is necessary to keep the stress (imposed by K imbalance) away in densely and late-planted cotton or not. For this, a 2-year field experiment was carried out with the application of three K rates relative to reduced N (210 kg ha−1) viz. K1 = 80% of N, K2 = 100% of N, and K3 = 120% of N. Under higher K supply (K2 and K3), cotton leaf exhibited a substantial increase in leaf mass, relative water content, and specific leaf area, while decreased lipid peroxidation and proline content compared with low K treatment. Low K application not only decreased these parameters but also enhanced the production of hydrogen peroxide along with increases in antioxidant enzyme activities. Similarly, higher K rates showed a significant increase in lint yield by 10–20% and 10–24% compared with K1 in 2016 and 2017, respectively. The negative relationship between antioxidant enzyme activity and leaf K concentration was recorded. These findings concluded that the K supply equal to or higher than N, helped the cotton plant to maintain a favorable nutritional balance for growth and metabolism. However, from the economic point of view, the K supply must be equal to N to obtain adequate yield and satisfactory profit in cotton.

Summary Tinospora sagittata (Oliv.) Gagnep. is an important medicinal tetraploid plant in the Menispermaceae family. Its tuber, namely “Radix Tinosporae” used in Traditional Chinese Medicine, is rich in medicinal terpenoids and benzylisoquinoline alkaloids (BIAs), To enhance understanding the biosynthesis of medicinal compounds, we, herein, report the assembly of a high quality chromosome-scale genome with both PacBio HiFi and Illumina sequencing technologies. The size of assembled genome was 2.33 Gb consisting of 4070 scaffolds (N50=42.06Mb), of which 92.05% were assigned to 26 pseudochromosomes in A and B sub-genomes. A phylogenetic analysis with the T. sagittata and other 16 plant genomes estimated the evolutionary placement of T. sagittata and its divergence time in Ranunculales. Further genome evolution analysis characterized one round tandem duplication about 1.5 million years ago (MYA) and one whole-genome duplication (WGD) about 86.9 MYA. WGD contributed to the duplication of clade-specific cytochrome P450 gene family in Ranunculales. Moreover, sequencing mining obtained genome-wide genes involved in the biosynthesis of alkaloids and terpenoids. TsA02G014550 , one candidate, was functionally characterized to catalyze the formation of ( S )-canadine in the jatrorrhizine biosynthetic pathway. Taken together, the assembled genome of T. sagittata provides useful sequences to understand the biosynthesis of jatrorrhizine and other BIAs in plants.

Tripterygium wilfordii Hook F. is a traditional medicinal plant known for its valuable secondary metabolites, including triptolide and celastrol, and can potentially be developed into pharmaceuticals. However, the production of these secondary metabolites in Tripterygium wilfordii is influenced by various environmental factors, making it essential to optimize fertilization techniques. This study aimed to measure the content of triptolide and celastrol in the above-ground and under-ground sections of Tripterygium wilfordii during three years of experiments in three types of growth media. Additionally, untargeted metabolomics analysis was conducted on Tripterygium wilfordii roots under five levels of nitrogen fertilizer rates. Excessive nitrogen fertilizer significantly increased the fresh shoot weight of Tripterygium willfordii and decreased the plant height and fresh root weight, whereas nitrogen fertilizer deficiency significantly decreased the fresh shoot and root weight, as well as the plant height. Additionally, both excessive and deficient nitrogen fertilizer levels limited the accumulation of triptolide and celastrol in Tripterygium wilfordii roots and shoots, with higher content observed at a moderate fertilizer level. This study also identified a total of 197 alkaloids, 216 flavonoids, 12 lignans, 25 coumarins, 227 phenolic acids, 13 tannins, 147 terpenoids, and 43 other secondary metabolites. Notably, alkaloids were up-regulated at a moderate nitrogen fertilizer level (30-60 g N/pot), whereas flavonoids were down-regulated at a higher nitrogen level (90-120 g N/pot). These findings emphasize the value of nitrogen fertilizer and controlled growth conditions in enhancing the production of secondary metabolites in Tripterygium wilfordii.