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There are currently many problems related to excessive fertilizer application, low fertilizer-use efficiency and lack of an agricultural labor force for cotton production in China. Therefore, the objective of this paper was to explain the optimal application time for once fertilization based on cotton nutrient accumulation of nitrogen, phosphorus and potassium to provide technical support for simplified fertilization management in cotton production. A 2 yr field experiment and a 1 yr pot experiment were conducted with fertilizer (225, 67.5, and 225 kg ha−1 of N, P2O5, and K2O, respectively) applied once at 0 (FT1), 5 (FT2), 10 (FT3), 15 (FT4), or 20 (FT5) d after the appearance of the first flower and a triple application (preplant 30%, first bloom 40%, and peak bloom 30%) as the conventional control (FT6). The results showed that FT1 exhibited the greatest nutrient accumulation speed for both the average (5.81, 1.22, and 5.74 kg ha−1 of N, P2O5, and K2O, respectively) and the maximum (6.31, 1.44, and 6.24 kg ha−1 of N, P2O5, and K2O, respectively) during the fast accumulation period. Moreover, among the different treatments, FT1 exhibited the greatest nutrient recovery and partial productivity. The results suggest that applying the minimum amount of fertilizer at the appearance of the first flower is optimal for maximizing nutrient utilization while minimizing environmental disturbance. [ABSTRACT FROM AUTHOR]

Improving the management of water and fertilizers is an effective method for enhancing the seed‐setting performance of rice. This study aimed to explore the regulation of optimized water and nitrogen management on the root–leaf hormone balance and seed‐setting performance of drip‐irrigated rice. In a 2‐year field experiment, T‐43 (a drought‐resistant cultivar) and LX‐3 (a drought‐sensitive cultivar) were cultivated under two drip irrigation treatments (W1, limited, and W2, deficit) and three nitrogen fertilization treatments (N1, seedling:tillering:panicle:grain‐filling, 30%:50%:13%:7%; N2, 20%:40%:30%:10%; and N3, 10%:30%:40%:20%). Compared with other treatments, the W1N2 treatment increased the seed‐setting rate and grain biomass accumulation (2.7%–9.2% and 4.5%–69.8%) of the two cultivars on the basis of producing a higher effective panicle number, and T‐43 had a much higher seed‐setting rate and yield than LX‐3 (6.8%–14.6%). Increased fertilizer applications at the panicle and grain‐filling stages (N2) enhanced the root oxidation activity (ROA) and the zeatin+zeatin riboside (Z + ZR) and gibberellic acid (GA3) contents in the roots in the 0–10 cm layer and in the leaves from the heading stage to 20 days after heading. The grain biomass accumulation of T‐43 was significantly positively correlated with abscisic acid (ABA) and Z + ZR in the roots and leaves, while the grain biomass accumulation of LX‐3 was significantly positively correlated with auxin, ABA, Z + ZR/ABA, and GA3/ABA in the roots in the 10–20 cm layer. Overall, W1N2 promoted grain biomass accumulation by modulating the Z + ZR and ABA balance in roots and leaves, improved the root–shoot ratio, and enhanced ROA, thereby improving the seed‐setting performance of drip‐irrigated T‐43 rice. Core Ideas: Optimized water and nitrogen management improved seed‐setting rate on the basis of higher effective panicles.Increasing panicle and grain fertilizer enhanced the hormone content and root activity in 0–10 cm.The balance of the hormone content in roots and leaves promoted the transport of assimilates to grain. [ABSTRACT FROM AUTHOR]

BACKGROUND: Optimizing biochar application is vital for enhancing crop production and ensuring sustainable agricultural production. A 3‐year field experiment was established to explore the effects of varying the biochar application rate (BAR) on crop growth, quality, productivity and yields. BAR was set at 0, 10, 50 and 100 t ha−1 in 2018; 0, 10, 25, 50 and 100 t ha−1 in 2019; and 0, 10, 25 and 30 t ha−1 in 2020. Crop quality and growth status and production were evaluated using the dynamic technique for order preference by similarity to ideal solution with the entropy weighted method (DTOPSIS‐EW), principal component analysis (PCA), membership function analysis (MFA), gray relation analysis (GRA) and the fuzzy Borda combination evaluation method. RESULTS: Low‐dose BAR (≤ 25 t ha−1 for cotton; ≤ 50 t ha−1 for sugar beet) effectively increased biomass, plant height, leaf area index (LAI), water and fertility (N, P and K) productivities, and yield. Biochar application increased the salt absorption and sugar content in sugar beet, with the most notable increases being 116.45% and 20.35%, respectively. Conversely, BAR had no significant effect on cotton fiber quality. The GRA method was the most appropriate for assessing crop growth and quality. The most indicative parameters for reflecting cotton and sugarbeet growth and quality status were biomass and LAI. The 10 t ha−1 BAR consistently produced the highest scores and was the most economically viable option, as evaluated by DTOPSIS‐EW. CONCLUSION: The optimal biochar application strategy for improving cotton and sugar beet cultivation in Xinjiang, China, is 10 t ha−1 biochar applied continuously. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Deep drip irrigation combined with high‐density planting is one of the most economical and effective ways to address residual film pollution. This study aimed to explore the photosynthetic potential of and achieve water‐saving and high‐yielding filmless cotton (Gossypium hirsutum L.) by optimizing the irrigation amount. We analyzed the effect of source leaf activity on leaf nitrogen allocation and photosynthetic nitrogen utilization efficiency (PNUE) under different irrigation amounts (mm, 375 (W5), 348 (W4), 320 (W3), 293 (W2), and 265 (W1)) in a 2‐year field experiment under this planting mode. The photosynthetic pigment content, leaf mass per area, and light compensation point all decreased with increasing amounts of irrigation, while the apparent quantum yield of photosynthesis, light saturation point, maximum carboxylation rate (Vcmax), maximum electron transport rate (Jmax), triose phosphate utilization rate (VTPU), nitrogen content in the electron transfer component (NB), and nitrogen content in the carboxylation component (NC) showed opposite trends. At the later full boll stage, the W3 and W4 treatments increased the leaf area of a whole plant (LA) by 10.4% and 19.4%, respectively, compared to that in the W1 treatment, while the PNUE increased by 20.2% and 20.8%, respectively, compared to that in the W5 treatment. In addition, principal component analysis found that the factor variables total nitrogen content in the photosynthetic apparatus (NT), net photosynthetic rate (Pn), stomatal conductance (Gs), light‐saturated net photosynthetic rate (Amax), NC, and Vcmax had higher loadings and were all positively correlated with PNUE; LA had a higher loading and was positively correlated with reproductive organ biomass. Therefore, we recommend using an irrigation rate of 320 mm in this cultivation system to increase nitrogen in carboxylation and electron transport components, enhance photosynthetic capacity, and thereby improve PNUE to increase reproductive organ biomass and reduce the irrigation amount in arid areas. Core Ideas: Optimizing the irrigation amount can enhance the source leaf activity of filmless cotton.The content of nitrogen in carboxylation and electron transport components is the key to improve photosynthetic rate.Increasing the leaf area of a whole plant can increase reproductive biomass.The optimal irrigation system rate is 320 mm under deep drip irrigation without film. [ABSTRACT FROM AUTHOR]

Soil degradation and associated environmental problems caused by the excessive use of fertilizers are the main challenges in agricultural production in arid or semiarid areas. The partial substitution of chemical fertilizer with organic manure fertilizer is an important measure for reducing fertilizer usage and improving agricultural production efficiency. We hypothesized that integrated water and fertilizer application under mulched drip irrigation and the optimization of organic liquid fertilizer (OLF) and chemical fertilizer application can result in the regulation of spatiotemporal differences in soil nutrient supply and cotton nutrient absorption efficiency and allow for simultaneous increases in cotton yield and fertilizer use efficiency. To test this hypothesis, three fertilization treatments were employed: no fertilizer (CK), chemical fertilizer (CF), and organic liquid fertilizer (OLF) combined with chemical fertilizer at five different ratios, with F0.6, F0.8, F1.0, F1.2, and F1.4 corresponding to 0.6, 0.8, 1.0, 1.2, and 1.4 of CF, respectively. In this paper, the effects of organic liquid fertilizer combined with chemical fertilizer application on soil nutrient content, dry matter accumulation, nutrient uptake, yield and fertilizer utilization efficiency were investigated through two years of field experiments. Our results demonstrated that compared to chemical fertilizer treatment, combined OLF and chemical fertilizer application in the F0.8 treatment substantially increased soil organic matter content by an average of 13.4% in shallow soils (0–20 cm) without affecting nitrate nitrogen, quick-acting phosphorus or quick-acting potassium levels. Furthermore, in the F0.8 treatment, a remarkable decrease in Mn and Fe content was observed in shallow soils (0–20 cm, wide rows), while Cu and Zn content significantly increased in the 40–100 cm soil layers (narrow rows). Compared with the CF treatment, this combined application strategy substantially enhanced the uptake of nitrogen (N), phosphorus (P 2 O 5), and potassium (K 2 O) in cotton plants, with average increases of 7.8−45.0%, 4.9−35.0%, and 6.0−25.0%, respectively. Additionally, it shortened the N and P2O5 rapid accumulation duration and increased the rate of accumulation by an average of 25.0∼37.0%, facilitating efficient nutrient transfer to cotton bolls. OLF combined with chemical fertilizer application significantly increased the efficiency of nitrogen and phosphorus fertilizer use in cotton. Moreover, seed cotton yield in the combined treatments increased by an average of 3.7–26.7% compared to that in the CF treatment, and the greatest increase was found in the F0.8 treatment. Overall, our findings suggest that in mulched drip irrigation systems, OLF with chemical fertilizer application can enhance soil organic matter content and nutrient availability, optimize nutrient uptake and distribution in cotton plants, and improve seed cotton yield and nutrient use efficiency. [Display omitted] ● Liquid organic fertilizer improves soil quality by increasing soil organic matter and available nutrients. ● Liquid organic fertilizer significantly improves the absorption and accumulation of N and P in plants. ● Liquid organic manure substitution increased yield and fertilizer use efficiency. ● This fertilization strategy has achieved a reduction in fertilizer usage and sustainable development. [ABSTRACT FROM AUTHOR]

Background: Water deficit (WD) has serious effect on the productivity of crops. Formation of cuticular layer with increased content of wax and cutin on leaf surfaces is closely related to drought tolerance. Identification of drought tolerance associated wax components and cutin monomers and the genes responsible for their biosynthesis is essential for understanding the physiological and genetic mechanisms underlying drought tolerance and improving crop drought resistance. Result: In this study, we conducted comparative phenotypic and transcriptomic analyses of two Gossypium hirsutum varieties that are tolerant (XL22) or sensitive (XL17) to drought stress. XL17 consumed more water than XL22, particularly under the WD conditions. WD significantly induced accumulation of most major wax components (C29 and C31 alkanes) and cutin monomers (palmitic acid and stearic acid) in leaves of both XL22 and XL17, although accumulation of the major cutin monomers, i.e., polyunsaturated linolenic acid (C18:3n-3) and linoleic acid (C18:2n-6), were significantly repressed by WD in both XL22 and XL17. According to the results of transcriptome analysis, although many genes and their related pathways were commonly induced or repressed by WD in both XL22 and XL17, WD-induced differentially expressed genes specific to XL22 or XL17 were also evident. Among the genes that were commonly induced by WD were the GhCER1 genes involved in biosynthesis of alkanes, consistent with the observation of enhanced accumulation of alkanes in cotton leaves under the WD conditions. Interestingly, under the WD conditions, several GhCYP86 genes, which encode enzymes catalyzing the omega-hydroxylation of fatty acids and were identified to be the hub genes of one of the co-expression gene modules, showed a different expression pattern between XL22 and XL17 that was in agreement with the WD-induced changes of the content of hydroxyacids or fatty alcohols in these two varieties. Conclusion: The results contribute to our comprehending the physiological and genetic mechanisms underlying drought tolerance and provide possible solutions for the difference of drought resistance of different cotton varieties. [ABSTRACT FROM AUTHOR]

The application of organic liquid fertilizer combined with chemical fertilizer is one of the key technologies used to simultaneously improve cotton yield and efficiently utilize resources. However, organic fertilizer is usually applied once as a base fertilizer during production, and few studies have been conducted on topdressing with water during the growth period. Therefore, in this study, Xinluzao 74 was used as the experimental material, and a single fertilizer application (CF) was used as a control in 2019–2020 under the conditions of integrated control of water and fertilizer with mulch drip irrigation. Five combinations of reduction in chemical fertilizer combined with organic fertilizer (OF1, OF2, OF3, OF4, and OF5) were used to investigate the influences of chemical fertilizer combined with organic liquid fertilizer on the leaf area index (LAI), canopy openness (DIFN), mean foliage tilt angle (MTA), photosynthetically active radiation (PAR), canopy apparent photosynthesis (CAP), and yield and quality of cotton. The results show that among the different fertilization treatments, the OF2 treatment had the best results, not only ensuring a suitable LAI (4.8) and maintaining a large DIFN (0.1) but also increasing the light transmittance of the middle and lower canopies (0.02–0.03). At the same time, CAP increased significantly compared with that in the CF treatment, with an average increase of 12.8%. The high value lasted for a long time, and the late decay stage remained at 8.9 μmol m−2 s−1. The ratio of the population respiration rate to total photosynthesis (CR/TCAP) decreased significantly, with an average decrease of 13.5%. Compared with that in CF, the lint yield increased by 27.0% in the other treatments. The correlation analysis showed that lint yield was positively correlated with the relative chlorophyll content (SPAD value), PAR transmittance (PARU) and CAP in the upper canopy (p < 0.05) and significantly negatively correlated with PAR transmittance (PARM) in the middle canopy and PAR transmittance (PARD) and CR/TCAP in the lower canopy (p < 0.05). Therefore, under mulch drip irrigation, the OF2 treatment (OF + 80% CF) improved the canopy structure of cotton at the late growth stage, increased the population photosynthetic rate, and increased lint yield significantly; thus, this approach can be used as an effective fertilization method to achieve the goal of decreasing costs and increasing efficiency in cotton production. [ABSTRACT FROM AUTHOR]

Sophora lopecuroides L. is a medicinal plant containing a variety of biologically active substances, in which alkaloids are the main active substances, and a variety of alkaloids have been identified in S. alopecuroides. Drought stress can stimulate the accumulation of biologically active substances in medicinal plants. In this respect, the imposition of appropriate degree of drought stress may be an effective way to increase the alkaloid content in S. alopecuroides. However, the changes in the types and abundance of alkaloids in S. alopecuroides under drought stress and the molecular mechanism of regulating alkaloid biosynthesis are still unclear. In this study, the metabolome and transcriptome analysis were conducted to explore the influence of mild (D1), moderate (D2), and severe (D3) drought stress on the types and abundance of alkaloids in S. alopecuroides , and to identify the key regulatory genes in the alkaloid synthesis pathways. The results showed that the total alkaloid content in S. alopecuroides in the D1 and D2 group significantly decreased by 13.49% and 10.40%, respectively compared with that in the control group, but the total alkaloid content in S. alopecuroides in the D3 group significantly increased by 8.16% compared with that in the control group. Sixty-eight alkaloids were identified in S. alopecuroides , with quinolizidine alkaloids being the main type of alkaloids. Of the 25 differentially accumulated metabolites (DAMs), the number of DAMs with increased relative abundance in the D1, D2, and D3 group were 0, 7, and 20, respectively. The relative abundance of 6 DAMs increased in both D2 and D3 group, and 14 DAMs only increased in the D3 group such as methoxyindoleacetic acid, indole, and piperidine. Besides, the biosynthetic pathways of three major types of alkaloids (quinolizidine-, piperidine-, and plumerane-type alkaloids) were illustrated, and key genes (i.e., asd , DapL , PrAOs , DDC , and ALDH) associated with the alkaloid biosynthesis were identified. This study also found that 22 TFs (SaERF1 ∼ SaERF5 , SaWRKY1 ∼ SaWRKY3 , SabHLH1 ∼ SabHLH3 , SaMYB1 ∼ SaMYB6 , SabZIP1 ∼ SabZIP5) were positively correlated with the alkaloid biosynthesis. This study deepens our understanding of the molecular mechanism of S. alopecuroides in response to drought stress, and helps to develop biotechnology strategies to manipulate the level of alkaloids in S. alopecuroides. [Display omitted] • Severe drought stress promotes alkaloid biosynthesis in Sophora alopecuroides. • Quinolizidine alkaloids are the main type of alkaloids in Sophora alopecuroides. • asd , DapL , PrAOs , DDC , and ALDH are the key genes regulating alkaloid biosynthesis. • SaERFs , 3 SaWRKYs , 3 SabHLHs , 6 SaMYBs , and 5 SabZIPs affect alkaloid biosynthesis. [ABSTRACT FROM AUTHOR]

Premature senescence is a major concern for crop production especially for high-density cotton in Xinjiang, China, when nitrogen (N) rates are reduced. This study aimed to examine the potential of late N fertilization in mitigating senescence, improving light and N use efficiency, and enhancing cotton productivity under reduced N rate. A three-year field experiment was conducted from 2019 to 2021, employing a total of 240 kg N ha-1, which was one-third lower than the traditional rate of 360 kg ha-1. Five different N application ratios based on cotton stages were tested, with N 064 (0:6:4 ratio at early: middle: late growth stages) representing late N fertilization, and N 262 representing traditional ratio in fertilization. The effects of N application timing-based ratios on yield components, N use efficiency, canopy photosynthesis, and root traits were evaluated. The results showed that N 064 had the highest lint yield 2727–3305 kg ha-1 (2019–2021) among all treatments over the three years. Late N fertilization (N 064) resulted in significant increases in boll density (4.6–10.7%), seed cotton yield (5.8–8.1%), and N use efficiency (10.5–14.1%) when compared to traditional N 262. During late peak boll-setting to boll opening stages, N 064 decreased leaf area index (3.5–6.6%), canopy light interception rate (3.8–11.4%), and boll capacity of root (18.1%) compared to N 262 , while increasing SPAD (2.3–4.8%), diffuse non-interceptance (3.9–16.6%), canopy apparent photosynthetic rate (13.2–49.4%), root biomass (19.5%), root/shoot ratio (15.0%). N 064 also resulted in a higher root surface area density in deep soil than N 262. Late N fertigation enhanced post-flowering canopy photosynthetic production by improving the cotton root-shoot relationship and delaying root and canopy senescence, resulting in improved yields and N use efficiency. This N management strategy implemented under reduced N cultivation shows promise for sustainable cotton production in Xinjiang and similar ecological regions. • Shifting N to late fertilization inhibited canopy senescence and improved light penetration. • Early N deficit increased root biomass and deep root surface area. • Late N fertilization alleviated pressure on roots to load bolls. • The optimized root-shoot relationship and their architecture improved production efficiency. [ABSTRACT FROM AUTHOR]

• Limited irrigation under high population levels are beneficial in terms of saved irrigation without reducing yield. • Leaf area index and radiation use efficiency in upper and middle canopy provides carbohydrates during boll formation. • Improvements in lint yield and water use efficiency depends on effective conservation of radiation use efficiency. Increasing plant density under insufficiency or deficit irrigation is considered a new water-saving technique in cotton production, especially in Xinjiang, China, an arid area with a short growing period. Increasing plant density reduces light intensity within the canopy; therefore, we hypothesized that resource use efficiency may be the main factor affecting cotton yield and water use efficiency under limited irrigation conditions. To test this hypothesis, 2-year field experiments were conducted to explore the effects of two irrigation patterns (I 500 , conventional irrigation; I 425 , limited irrigation) and three planting densities (D 12 , 12; D 24 , 24; D 36 , 36 plants m−2) on cotton yield, fiber quality, light interception rate, canopy photosynthesis and irrigation water use efficiency (IWUE). I 425 D 36 raised yield and IWUE by 1.40–22.4% and 13.4–34.5%, respectively, but it did not affect fiber quality compared with other treatments. Further, I 425 D 36 increased the leaf area index and the top- and middle-canopy light interception rates after 105 days after sowing, which improved the canopy apparent photosynthetic rate. Seed cotton yield was associated with leaf area index and the top- and bottom-canopy light interception rates. We conclude that irrigation of cotton with limited irrigation at a 425-mm level and a plant density at 36 plants m−2 had significant benefits in terms of economized irrigation without reducing yield in arid areas. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer and fortified DPC (DPC+) chemical topping agent management is essential for replacing manual topping and achieving simplified cotton cultivation. However, the response of cotton physiological characteristics to the interaction between nitrogen fertilizer and DPC+ and the relationship between this interaction and yield remain unclear. A 2-year field experiment was conducted to investigate the effects of nitrogen rates (N 1 , 150; N 2 , 300; N 3 , 450 kg ha−1) and DPC+ doses (D 1 , 450; D 2 , 750; D 3 , 1050 mL ha−1) and D 0 (manual topping) on antioxidant enzymes, endogenous hormone content and balance, reproductive organ dry matter (RODM) and yield. N 1 D 1 , N 2 D 2 , and N 3 D 3 significantly improved the RODM and yield, with N 2 D 2 having 3.5 − 37.1% higher RODM levels than N 1 D 1 and N 2 D 2. At the N 1 level, D 1 decreased malondialdehyde (MDA) content by 4.1 − 35.6% compared to D 0 , D 2 and D 3 , and increased catalase (CAT) activity and abscisic acid (ABA) content by 69.7% and 34.2% than D 0 , respectively. At the N 2 level, D 2 decreased the MDA content by 16.1 − 51.9% and increased peroxidase and CAT activity and ABA and gibberellic acid contents by 12.7 − 355.7% compared to D 0 , D 1 , and D 3. Furthermore, D 2 decreased indole-3-acetic acid (IAA) content and IAA/ABA by 12.1% and 30.5% in boll opening but increased trans-zeatin-riboside (ZR) content by 25.5% compared to D 0. At the N 3 level, D 3 increased ZR/ABA by 20.1% compared to D 0. Overall, the interactions between appropriate nitrogen levels and DPC+ doses can increase cotton yield by enhancing antioxidant enzyme activity and promoting endogenous hormone homeostasis, with N 2 D 2 performing best. • Appropriate nitrogen levels and DPC+ doses decreased cotton malondialdehyde content. • Appropriate nitrogen levels and DPC+ doses can enhance antioxidant enzyme activity. • Appropriate nitrogen levels and DPC+ doses can promote endogenous hormone homeostasis and a dynamic balance between hormones. • Maintained endogenous hormone balance in the late growth stage is conductive to reproductive organ dry matter and yield increment. [ABSTRACT FROM AUTHOR]

Highlights • We evaluated the effect of presowing fertigation on water use in cotton. • Presowing fertigation increased soil water absorption and promoted transportation. • Presowing fertigation enhanced water productivity after the full flowering stage. • Presowing fertigation led to high ability of aerial parts to compete for water. Abstract To increase the yield and water-use efficiency of cotton in arid regions, irrigation and fertilizer management must be optimized. This study evaluated the effects of two irrigation levels (i.e., with (W 80 ) and without (W 0 ) presowing irrigation) combined with two basal fertilization methods (i.e., surface application (F 10 ) and deep application (F 30 )) on soil water absorption and transport, and relationships with water-use efficiency. Our results showed significantly positive relationships between water-use efficiency and the root surface area in the 0–30 cm soil layer (RSA-30), root vigor in the 0–30 cm soil layer (RV-30), root vigor in the 60–80 cm soil layer (RV-80), the leaf transpiration rate, stomatal conductance, sap flow, and water productivity. Principal component analysis showed that the W 80 F 10 treatment initially positively influenced RSA-30, RV-30, and RV-80 and that these parameters affected the leaf transpiration rate, stomatal conductance, sap flow, and leaf area (i.e., the main transpiration area), which finally influenced water productivity and water-use efficiency. In addition, the W 80 F 10 treatment increased the ability of aerial parts to compete for water after 69 days after emergency. These findings indicate that the combination of presowing irrigation and basal fertilizer surface application can enhance the ability of aerial parts to compete for water and increase water-use efficiency by promoting water absorption and consumption after the full flowering stage. This research provides valuable information on agricultural management in aridregions. [ABSTRACT FROM AUTHOR]

Appropriate drought stress could promote the accumulation of specialized metabolites in plants, especially in medicinal plants. Sophora alopecuroides L. (Leguminosae), a medicinal plant with a variety of bioactive specialized metabolites, has an excellent drought resistance. In this study, drought stress-induced metabolomic and transcriptomic changes in S. alopecuroides were identified, to explore the mechanism of specialized metabolite changes in response to mild, moderate and severe drought stress. The metabolic analysis results showed that a total of 919 annotated metabolites were detected and quantified, of them, flavonoid metabolites were the main metabolites in S. alopecuroides. Moreover, a total of 411 differentially accumulated metabolites (DAMs) were identified, among them, 6-Hydroxydaidzein, 2-Hydroxy-2,3-dihydrogenistein, prunetin, and biochanin A significantly increased under mild drought stress but isoflavonoids significantly decreased under moderate and severe drought stress. Transcriptional analysis showed that a total of 21,307 differentially expressed genes (DEGs) were identified, and most of them were enriched in the biosynthesis of secondary metabolites pathway. The integrated metabolomic and transcriptomic analyses results proved that these DAMs and DEGs were most significantly enriched in isoflavonoid biosynthesis pathway (ko00943). In addition, some structural genes such as 2-hydroxyisoflavanone synthase (IFS), 2-hydroxyisoflavanone dehydratase (HID), isoflavone 7-O-glucosyltransferase (IF7GT), and isoflavone 7-O-glucoside-6''-O-malonyltransferase (IF7MAT) and seven MYB transcription factors (SaMYB1 ∼ SaMYB7) were identified, which played crucial regulatory roles in the isoflavonoid synthesis. This study provides useful insights into the molecular mechanism of S. alopecuroides in response to drought stress, and help develop biotechnological strategies to manipulate the levels of therapeutic specialized metabolites in S. alopecuroides. • Flavonoids were the main specialized metabolites in Sophora alopecuroides L. • Mild drought stress promoted the accumulation of flavonoid metabolites. • Structural genes (IFS , HID , IF7GT , and IF7MAT) contributed to the isoflavonoid accumulation. • Seven SaMYBs may involve in the regulation of isoflavonoid biosynthesis. [ABSTRACT FROM AUTHOR]

Nitrogen (N) loss is becoming one of the main limitations for sustainable agricultural production globally, particularly for crops such as cotton. 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. Two field experiments were carried out to investigate cotton yield, N use efficiency (NUE), N accumulation characteristics, and 15N 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). 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 (∆t) shortened by 15.2–24.4%. N 064 partitioned 15.6% more 15N to reproductive organs. NUE was significantly positively correlated with K, t 1 (the day when ∆t started), Vt, Vm, Tm (the day on which Vm occurred) and 15N accumulation in middle and upper canopy bolls, and negatively correlated with ∆t of total N accumulation in reproductive organs. 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. This N management strategy is a potential way to improve NUE and achieve sustainable and efficient production of cotton in arid areas. • 240 kg N ha−1 with wide-row and high-density planting was a N-reduced cultivation pattern. • Early N starvation increased cotton yield and NUE under N-reduced cultivation. • The increased in NUE was due to higher total N accumulation in reproductive organs. • Higher total N in reproductive organs was because of more fertilizer N allocated to bolls. [ABSTRACT FROM AUTHOR]

Plant population density (PPD) is an important practice for optimizing canopy structure and improving canopy photosynthetic capacity of field-grown cotton ( Gossypium hirsutum L.). A 2-yr field experiment was conducted to determine if and how PPD (7.5, 19.5 or 31.5 plants m −2 ) affects the light-saturated photosynthetic rate and photosynthetic nitrogen use efficiency in cotton leaves, with a focus on the key canopy characteristics for efficient utilization of light and nitrogen. The results showed that leaf N allocation and partitioning among different components of the photosynthetic apparatus were significantly affected by PPD. As PPD changed, cotton optimized photosynthetic N use efficiency and photosynthetic capacity by adjusting leaf mass per area, which in turn affected leaf N allocation to the photosynthetic apparatus. In the upper canopy layer, leaf N allocation to the photosynthetic apparatus increased as PPD increased, resulting in an increase in leaf photosynthetic N use efficiency. In contrast, in the mid- and lower-canopy layers, leaf N allocation to the photosynthetic apparatus decreased as PPD increased, resulting in declines in leaf light-saturated photosynthetic rate and photosynthetic N use efficiency. The overall results indicated that high photosynthetic capacity of leaves in the upper-canopy layer and high leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic nitrogen in the mid- and lower-canopy layers were two key canopy characteristics for efficient utilization of light and nitrogen by cotton. The medium-PPD is the optimum plant density due to high light utilization efficiency, superior spatial distribution of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N in leaves within the canopy. [ABSTRACT FROM AUTHOR]

Plastic film mulching under drip irrigation is a key cotton cultivation technology that can save water and increase yield in arid regions. However, the long-term promotion of film mulching has resulted in increasingly serious problems related to residual film pollution. We hypothesized that deep drip irrigation and optimized irrigation can ensure the sustainability of yield of non-film cotton; thus, film is not necessary under this planting system. To address the above issues, we investigated the effects of different irrigation volumes (in m3 ha−1: W 1 , 2649; W 2 , 2925; W 3 , 3201; W 4 , 3477; W 5 , 3753) on the soil water and salt distribution, agronomic attributes, biomass accumulation, yield composition and water use efficiency (WUE) of non-film cotton grown under deep drip irrigation in a two-year field trial. We also explored possible ways to exploit the full potential of decreasing water consumption and enhancing cotton production. The results showed that the seed cotton yield of W 3 was 7.5%, 7.1% and 3.2% higher than those of W 1 , W 2 and W 5 , respectively, while it was 5.2% lower than that of W 4 across the two-year study. Moreover, there was no significant difference in seed yield or WUE between the W 3 and W 4 treatments. Compared with the W 2 treatment, the W 3 treatment delayed the total growth period by only 0–2 d, the conductivity in the 0–10 cm soil layer was increased by 9.3–22.9%, and the soil water content in the 0–20 cm soil layer was increased by 1.7–4.0%. The cotton plant biomass and reproductive organ biomass increased with the amount of irrigation and followed this order W 5 > W 4 , W 3 , W 2 > W 1. Seed cotton yield was significantly correlated with effective bolls, while WUE was negatively correlated with vegetative organ biomass at the flowering and boll setting stages. Overall, the results suggested that under the non-film conditions, an irrigation amount of 3201 m3 ha−1 would improve the eco-friendliness and efficiency of cotton production systems in arid regions. • Non film deep-drip irrigation (NDI) system can solve the residual membrane pollution. • Salt accumulates on the surface of the soil under NDI system. • Optimizing irrigation under NDI system can achieve high-efficiency cotton production. • Maintaining proper vegetative organs in the later growth stage is conducive to yield increment. [ABSTRACT FROM AUTHOR]

In the arid region of Northwest China, exploring the feasibility of using non-film deep drip irrigation (DDI) instead of film drip irrigation to solve the problem of residual film pollution is an urgent task. Therefore, in this study, we hypothesized that efficient and clean production can be achieved by optimizing the irrigation amount of non-film cotton, thus improving the canopy environment and increasing the accumulation and distribution of biomass. A 2-year field experiment was performed to compare the cotton canopy microenvironment, biomass accumulation, lint cotton yield and fibre quality attributes under various irrigation levels. The experiment was arranged in a randomized complete block design with five irrigation amount treatments (m3 ha−1): 2649 (W 1); 2925 (W 2); 3201 (W 3); 3477 (W 4); and 3753 (W 5). The results revealed that an increase in the irrigation amount decreased the transmittance of canopy photosynthetically active radiation (PAR) by 4.1–18.7%, while the cotton plant biomass (CPB) and reproductive organ biomass (ROB) were significantly increased by 7.6–5.9% and 22.0–54.1%, respectively. The fibre quality did not differ significantly among treatments. Moreover, under the W 4 treatment, the leaf area index (LAI), mean tilt angle (MTA), canopy humidity and cotton lint yield were increased by 1.4–22.3%, 0.3–8.7%, 0.6–2.9% and 4.4–18.7%, respectively, and the canopy temperature was decreased by 0.2–2.2% as compared to the other treatments. The lint cotton yield was negatively correlated with the canopy humidity from the initial squaring stage to the full boll stage. This comprehensive evaluative analysis suggests that the optimal irrigation amount of non-film cotton is 3477 m3 ha−1 under the studied conditions, and this irrigation method is recommended as an alternative to film drip irrigation as it allows cotton to be planted without worrying about plastic pollution in irrigated agricultural areas. This study enriches the high-efficiency cotton planting technologies of non-film DDI and provides scientific guidance for the further popularization and application of non-film cotton. Fig. 1 Graphical abstract illustrating the whole theme of the study. [Display omitted] • Deep-drip irrigation (DDI) can compensate the negative effects of non-film cotton cultivation on the canopy structure. • Increasing irrigation amount increased the leaf area index and mean tilt angle under DDI. • Lint cotton yield depends on the photosynthetically active radiation in the upper and middle canopy under DDI. • DDI without plastic mulching has the potential to replace mulched drip irrigation. [ABSTRACT FROM AUTHOR]

The plant growth regulator mepiquat chloride (1,1-dimethylpiperidinium chloride, DPC) has been successfully used worldwide in cotton production. Fortified DPC (DPC+) can slightly damage young tissues of the epidermis, which has shown potential in cotton chemical topping in China. The underlying mechanism remains unclear. We investigated whether apical meristem and leaf morpho-physiological traits contribute to delayed growth of the main stem and increased seed yield in DPC or DPC+ as a chemical inhibitor. Two different DPC-sensitive varieties (Xinluzao 60, L60; Jinken 1402, JK1402) were field-grown using three different topping treatments manual topping (MT), no topping (NT) and chemical topping (DPC+ and DPC) in irrigated arid lands of Xinjiang for two years. The plant height decreased by 1.4–13.6% for the DPC+ and DPC treatments compared with the NT treatment and increased by 3.8 –9.2% compared with the MT treatment. The thickness of the leaves, palisade tissue (Pt) and spongy tissue (St) increased by 5.1–21.5% under DPC treatment compared with other treatments. The 3-indoleacetic acid (IAA) content of the leaves significantly increased by 25.0–93.8% at 10 days under the DPC treatment compared with that under the MT and NT treatments. The zeatin riboside (ZR) content of the leaves and apical buds increased up to 7.5 times at 40 days under the DPC+ and DPC treatments compared with that under the NT treatment. The accumulation of reproductive organ biomass and proportion of reproductive organ dry matter to total dry matter under the DPC+ and DPC treatments increased by 2.0–39.7% compared with that under the MT and NT treatments. The seed cotton yield between the DPC+ and DPC treatments showed no significant difference. However, the seed cotton yield of JK1402 under the DPC+ and DPC treatments significantly increased by 9.5–11.7% compared with that under the MT and NT treatments. The main stem length was significantly correlated with the stem length of the upper part and gibberellin (GA) content in the apical buds. The leaf Pt and ZR contents were significantly correlated with the boll weight and seed cotton yield. Collectively, the data suggest that improved morpho-physiological traits of the apical part, such as an increase in the IAA and GA contents in the apical buds, leaf Pt and ZR contents, and boll weight, inhibited growth of the main stem and increased seed cotton yield for DPC, which is cheaper than DPC+ as a chemical inhibitor under chemical regulation during the whole growth period. • Chemical topping delays growth of the upper main stem. • Chemical topping enhances thickness and ZR contents of leaves. • DPC can increase boll weight and seed cotton yield in DPC-sensitive varieties. • DPC has the potential to replace manual and other chemical topping agents. [ABSTRACT FROM AUTHOR]

• Limited drip irrigation improves boll subtending leaves and capsule wall photosynthetic capacity. • Limited drip irrigation increased the maximum growth rate of seed cotton biomass. • Higher photosynthetic capacity of boll subtending leaves and thicker capsule wall favors more seed cotton yield. Drought stress is considered to be the main source of yield reduction around the world. Improving plant performance under stressful environments by understanding growth and physio-biochemical responses are important. However, the detail mechanism of how boll capsule wall and subtending leaves anatomy, physio-biochemical characteristics and key enzymes i.e. Ribulose-1,5-bisphosphate carboxylase (RUBPC) and phosphoenolpyruvate carboxylase (PEPC) affect cotton (Gossypium hirsutum L.) yield have not yet been reported. To cover this knowledge gap, a two-year field experiment evaluated three drip irrigation rates [W 1 (4800 m³ ha−1), W 2 (3840 m³ ha−1) and W 3 (2880 m³ ha−1)] effects on cotton main stem leaves, boll subtending leaves, capsule wall anatomy, biomass accumulation, RUBPC and PEPC activity. Compared with W 1 , W 2 had 10.4–15.7 %, 8.3–24.6 %, 4.4–22.7 % and 5.0–15.3 % higher boll subtending leaf net photosynthetic rate, chlorophyll content, RUBP and PEPC activity at 21–42 days after anthesis. The palisade tissue thickness at 35 DAA (days after anthesis) and the ratio of palisade tissue to sponge tissue (p/s) of boll subtending leaf during 21–49 DAA were 7.7 % and 3.6–10.2 % higher for W 2 over W 1. Under W 2 treatment,improvements in these attributes significantly prolonged biomass accumulation rate (T , 6.9 d and 22.1 d) of main stem leaves and boll subtending leaf resulted in the maximum growth rate of seed cotton weight (Vx , 0.195 g d-1). Conclusively, higher photosynthetic capacity of the boll subtending leaves during 21–42 DAA and thicker capsule wall are the main drivers for achieving higher seed cotton weight under limited drip irrigation systems in arid region. [ABSTRACT FROM AUTHOR]

• Presowing fetigation considerably increased root growth and physiological characteristics. • P absorption was positively associated with root length and acid phosphatase activity. • Sap flow had a negative relationship with root phosphorus content. • Presowing irrigation combined with basal surface fertilization improved P utilization. Phosphorus (P) plays a key role in regulating plants physio-biochemical processes of plants and is indispensable for cotton production. However, the mechanism how does root morpho-physiological characteristics can affect P uptake, assimilation and use efficiency in different soil layers at various fertigation depths have not been studied. To fill this knowledge gap, a two-year pot experiment under field conditions was conducted to evaluate the effects of two irrigation levels, i.e., presowing irrigation (W 80 , 0.28 m3 water equivalent to 80 ± 5 % field capacity) and no presowing irrigation (W 0 , no water applied to the entire depth of the tube), and two basal fertilization methods [surface application (F 10) and deep application (F 30)] on root physiology, biomass accumulation, P uptake, transportation, and distribution in the cotton crop. The W 80 treatment had 2.4–11.1% lower soil available P content (SAP) in the 0−50 cm soil layer but 6.1–14.4% higher SAP in the 60−120 cm soil layer than those in the W 0 treatment. In the fertilization treatments, F 10 had 0.35–17.0% greater SAP content in the 0−20 cm soil layer than F 30. The W 80 F 10 combination resulted in higher root length (RL) in the 0−20 cm soil layer, higher root acid phosphatase activity (ACP) in the 0−40 cm and 60−80 cm soil layers, and increased root phosphorus content (RP) in the 0−60 cm soil profile. W 80 F 10 increased sap flow (SF), dry matter, and P accumulation in the reproductive organs compared with those in the other treatments. P utilization was positively associated with RL and root ACP in the 0−40 cm soil layer. Root ACP RL in the 0−40 cm soil layer and root ACP in the 60−80 cm soil layer were also positively related with SF, but SF had a negative relationship with RP in the 0−60 cm soil layer. In conclusion, presowing irrigation in conjunction with basal surface fertilization can increase P absorption and translocation by improving RL and ACP in the 0−40 cm and 60−80 cm soil layers before the full flowering stage. This also improves the competitive ability of the reproductive organs to access RP in the 0−60 cm soil layer, leading to higher P utilization in cotton. [ABSTRACT FROM AUTHOR]

Due to the changing climate, frequent episodes of drought have threatened cotton lint yield by offsetting their physiological and biochemical functioning. An efficient use of irrigation water can help to produce more crops per drop in cotton production systems. We assume that an optimal drip irrigation with low mepiquat chloride application could increase water productivity (WP) and maintain lint yields by enhancing leaf functional characteristics. A 2-year field experiment determines the response of irrigation regimes (600 (W1), 540 (W2), 480 (W3), 420 (W4) 360 (W5) m3 ha−1) on cotton growth, photosynthesis, fiber quality, biomass accumulation and yield. Mepiquat chloride was sprayed in different concentration at various growth phases (see material section). Result showed that W1 increased leaf area index (LAI) by 5.3–36.0%, net photosynthetic rate (Pn) by 3.4–23.2%, chlorophyll content (Chl) by 1.3–12.0% than other treatments. Improvements in these attributes led to higher lint yield. However, no differences were observed between W1 and W2 in terms of lint and seed cotton yield, but W2 increased WP by 3.7% in both years. Compared with other counterparts, W2 had the largest LAI (4.3–32.1%) at the full boll stage and prolonged reproductive organ biomass (ROB) accumulation by 30–35 d during the fast accumulation period (FAP). LAI, the average (VT) and maximum (VM) biomass accumulation rates of ROB were positively correlated with lint yield. In conclusion, the drip irrigation level of 540–600 m3 ha−1 with reduced MC application is a good strategy to achieve higher WP and lint yield by improving leaf photosynthetic traits and more reproductive organ biomass accumulation. [ABSTRACT FROM AUTHOR]

The changing climatic conditions are causing erratic rains and frequent episodes of moisture stress; these impose a great challenge to cotton productivity by negatively affecting plant physiological, biochemical and molecular processes. This situation requires an efficient management of water-nutrient to achieve optimal crop production. Wise use of water-nutrient in cotton production and improved water use-efficiency may help to produce more crop per drop. We hypothesized that the application of nitrogen into deep soil layers can improve water-nitrogen productivity by promoting root growth and functional attributes of cotton crop. To test this hypothesis, a two-year pot experiment under field conditions was conducted to explore the effects of two irrigation levels (i.e., pre-sowing irrigation (W80) and no pre-sowing irrigation (W0)) combined with different fertilization methods (i.e., surface application (F10) and deep application (F30)) on soil water content, soil available nitrogen, roots morpho-physiological attributes, dry mass and water-nitrogen productivity of cotton. W80 treatment increased root length by 3.1%–17.5% in the 0–40 cm soil layer compared with W0. W80 had 11.3%–52.9% higher root nitrate reductase activity in the 10–30 cm soil layer and 18.8%–67.9% in the 60–80 cm soil layer compared with W0. The W80F10 resulted in 4.3%–44.1% greater root nitrate reductase activity compared with other treatments in the 0–30 cm soil layer at 54–84 days after emergence. Water-nitrogen productivity was positively associated with dry mass, water consumption, root length and root nitrate reductase activity. Our data highlighted that pre-sowing irrigation coupled with basal surface fertilization is a promising option in terms of improved cotton root growth. Functioning in the surface soil profile led to a higher reproductive organ biomass production and water-nitrogen productivity. [ABSTRACT FROM AUTHOR]