RNA editing factor SlORRM2 regulates the formation of fruit pointed tips in tomato.

Domestication of tomato (Solanum lycopersicum) has led to large variation in fruit size and morphology. The development of the distal end of the fruit is a critical factor in determining its overall shape. However, the intricate mechanisms underlying distal fruit development require further exploration. This study aimed to investigate the regulatory role of an organelle RNA recognition motif (RRM)-containing protein SlORRM2 in tomato fruit morphology development. Mutant plants lacking SlORRM2 exhibited fruits with pointed tips at the distal end. However, this phenotype could be successfully restored through the implementation of a "functional complementation" strategy. Our findings suggest that the formation of pointed tips in the fruits of the CR-slorrm2 mutants is linked to alterations in the development of the ovary and style. We observed a substantial decrease in the levels of indole-3-acetic acid (IAA) and altered expression of IAA-related response genes in the ovary and style tissues of CR-slorrm2. Moreover, our data demonstrated that SlORRM2 plays a role in regulating mitochondrial RNA editing sites, particularly within genes encoding various respiratory chain subunits. Additionally, the CR-slorrm2 mutants exhibited modified organellar morphology and increased levels of reactive oxygen species (ROS). These findings provide valuable insights into the mechanisms underlying the formation of fruit pointed tips in tomato and offer genetic resources for tomato breeding.

Phosphorylated SHMT2 Regulates Oncogenesis Through m6A Modification in Lung Adenocarcinoma.

Targeting cancer-specific metabolic processes is a promising therapeutic strategy. Here, this work uses a compound library that directly inhibits metabolic enzymes to screen the potential metabolic targets in lung adenocarcinoma (LUAD). SHIN1, the specific inhibitor of serine hydroxymethyltransferase 1/2 (SHMT1/2), has a highly specific inhibitory effect on LUAD cells, and this effect depends mainly on the overexpression of SHMT2. This work clarifies that mitogen-activated protein kinase 1 (MAPK1)-mediated phosphorylation at Ser90 is the key mechanism underlying SHMT2 upregulation in LUAD and that this phosphorylation stabilizes SHMT2 by reducing STIP1 homology and U-box containing protein 1 (STUB1)-mediated ubiquitination and degradation. SHMT2-Ser90 dephosphorylation decreases S-adenosylmethionine levels in LUAD cells, resulting in reduced N6-methyladenosine (m6A) levels in global RNAs without affecting total protein or DNA methylation. Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and RNA sequencing (RNA-Seq) analyses further demonstrate that SHMT2-Ser90 dephosphorylation accelerates the RNA degradation of oncogenic genes by reducing m6A modification, leading to the inhibition of tumorigenesis. Overall, this study elucidates a new regulatory mechanism of SHMT2 during oncogenesis and provides a theoretical basis for targeting SHMT2 as a therapeutic target in LUAD.

SUCLG2 Regulates Mitochondrial Dysfunction through Succinylation in Lung Adenocarcinoma.

Mitochondrial dysfunction and abnormal energy metabolism are major features of cancer. However, the mechanisms underlying mitochondrial dysfunction during cancer progression are far from being clarified. Here, it is demonstrated that the expression level of succinyl-coenzyme A (CoA) synthetase GDP-forming subunit ß (SUCLG2) can affect the overall succinylation of lung adenocarcinoma (LUAD) cells. Succinylome analysis shows that the deletion of SUCLG2 can upregulate the succinylation level of mitochondrial proteins and inhibits the function of key metabolic enzymes by reducing either enzymatic activity or protein stability, thus dampening mitochondrial function in LUAD cells. Interestingly, SUCLG2 itself is also succinylated on Lys93, and this succinylation enhances its protein stability, leading to the upregulation of SUCLG2 and promoting the proliferation and tumorigenesis of LUAD cells. Sirtuin 5 (SIRT5) desuccinylates SUCLG2 on Lys93, followed by tripartite motif-containing protein 21 (TRIM21)-mediated ubiquitination through K63-linkage and degradation in the lysosome. The findings reveal a new role for SUCLG2 in mitochondrial dysfunction and clarify the mechanism of the succinylation-mediated protein homeostasis of SUCLG2 in LUAD, thus providing a theoretical basis for developing anti-cancer drugs targeting SUCLG2.

Temporal and Spatial Dynamics of Organ Water Content in Maize with Different Senescence Types.

Understanding the water status of specific organs can be helpful in evaluating the life activities and growth conditions of maize. To accurately judge organ growth conditions and thus design appropriate interventions, it is necessary to clarify the true water dynamics of each maize organ. Using multiple maize cultivars with different growth periods, spatio-temporal water dynamics were analyzed here in the leaves, stalks, and ear components. Leaf water content was found to gradually decrease from both the bottom and top of the plant to the middle, whereas stalk water content decreased sequentially from the top to the bottom. Each successively higher node from the bottom of the plant was associated with decreases of 0.99% and 1.27% water content in the leaves and stalks, respectively. The water dynamics in leaves and internodes showed three clear stages: the slow loss, rapid loss, and balance stage. A water content of 60% appeared to be an irreversible turning point for initiation of senescence. Using normalized growth period as a measure, each of the tested cultivars could be assigned into one of two types based on their water dynamics: stay-water or general type. General-type cultivars had a shorter duration with a high water content and a water loss rate approximately twice as high as that of the stay-water type. This may have been related to the leaf senescence characteristics. However, the stay-water trait did not interfere with water dynamics of the ear components. Therefore, it may not be robust to evaluate the kernel dehydration of maize according to leaf senescence conditions due to the weak correlation between kernel water content and leaf senescence characteristics.

STUB1-mediated ubiquitination regulates the stability of GLUD1 in lung adenocarcinoma.

The dysregulation of glutamine metabolism provides survival advantages for tumors by supplementing tricarboxylic acid cycle. Glutamate dehydrogenase 1 (GLUD1) is one of the key enzymes in glutamine catabolism. Here, we found that enhanced protein stability was the key factor for the upregulation of GLUD1 in lung adenocarcinoma. We discovered that GLUD1 showed a high protein expression in lung adenocarcinoma cells or tissues. We elucidated that STIP1 homology and U-box-containing protein 1 (STUB1) was the key E3 ligase responsible for ubiquitin-mediated proteasomal degradation of GLUD1. We further showed that lysine 503 (K503) was the main ubiquitination site of GLUD1, inhibiting the ubiquitination at this site promoted the proliferation and tumor growth of lung adenocarcinoma cells. Taken together, this study clarifies the molecular mechanism of GLUD1 in maintaining protein homeostasis in lung adenocarcinoma, which provides a theoretical basis for the development of anti-cancer drugs targeting GLUD1.

Amino acid metabolism regulated by lncRNAs: the propellant behind cancer metabolic reprogramming.

Metabolic reprogramming is one of the main characteristics of cancer cells and plays pivotal role in the proliferation and survival of cancer cells. Amino acid is one of the key nutrients for cancer cells and many studies have focused on the regulation of amino acid metabolism, including the genetic alteration, epigenetic modification, transcription, translation and post-translational modification of key enzymes in amino acid metabolism. Long non-coding RNAs (lncRNAs) are composed of a heterogeneous group of RNAs with transcripts of more than 200 nucleotides in length. LncRNAs can bind to biological molecules such as DNA, RNA and protein, regulating the transcription, translation and post-translational modification of target genes. Now, the functions of lncRNAs in cancer metabolism have aroused great research interest and significant progress has been made. This review focuses on how lncRNAs participate in the reprogramming of amino acid metabolism in cancer cells, especially glutamine, serine, arginine, aspartate, cysteine metabolism. This will help us to better understand the regulatory mechanism of cancer metabolic reprogramming and provide new ideas for the development of anti-cancer drugs. Video Abstract.

Reducing plastic film mulching and optimizing agronomic management can ensure food security and reduce carbon emissions in irrigated maize areas.

Increasing crop yields to ensure food security while also reducing agriculture's environmental impacts to ensure green sustainable development are great challenges for global agriculture. Plastic film, widely used to improve crop yield, also creates plastic film residue pollution and greenhouse gas emissions that restricts the development of sustainable agriculture. So, one of those challenges is to reduce plastic film use while also ensuring food security, and thus promote green and sustainable development. A field experiment was conducted during 2017-2020 at 3 farmland areas, each with different altitudes and climate conditions, in northern Xinjiang, China. We investigated the effects on maize yield, economic returns, and greenhouse gas (GHG) emissions of plastic film mulching (PFM) versus no mulching (NM) methods in drip-irrigated maize production. We also chose maize hybrids with 3 different maturation times and used 2 planting densities to further investigate how those differences more specifically affect maize yield, economic returns, and greenhouse gas (GHG) emissions under each mulching method. We found that by using maize varieties with a utilization rate of accumulated temperature (URAT) <86.6 % with NM, and increasing the planting density by 3 plants m-2, yields and economic returns improved and GHG emissions reduced by 33.1 %, compared to those of PFM maize. The maize varieties with URATs between 88.2 % to 89.2 %, had the lowest GHG emissions. We discovered that by matching the required accumulated temperatures of various maize varieties to environmental accumulated temperatures, along with filmless and higher density planting, and modern irrigation and fertilization practices, yields increased and residual plastic film pollution and carbon emissions reduced. Therefore, these advances in agronomic management are important steps toward reducing pollution and achieving carbon peak and carbon neutrality goals.

Improving maize quality from mechanical grain harvesting by matching maize varieties with accumulated temperature in northeast China.

BACKGROUND: Global warming has led to methods of planting late-maturing maize varieties in northeast China that have hindered the development of physiological maturity (PM) at harvest and the use of mechanical grain harvesting (MGH). Under these conditions it is difficult to balance the drying characteristics of maize varieties and to make full use of accumulated temperature resources in such a way as to reduce grain moisture content (GMC) at harvest. RESULTS: The effective accumulated temperature (AcT) and the drying rates of different varieties vary. In northeast China, with a GMC of 25%, the growth periods of a fast-drying variety (FDV) and a slow-drying variety (SDV) were 114-192 days and 110-188 days respectively. After PM, the FDV needed 47 days and the SDV needed 51 days to reduce the GMC to be ready for MGH. Harvested with a GMC of 20%, the growth period for the FDV was 97-175 days and for the SDV it was 90-171 days. After PM, the FDV required 64 days and the SDV needed 70 days to reduce the GMC to be ready for MGH. CONCLUSION: Matching cultivars with AcT can help farmers to choose suitable varieties. Promoting MGH may boost maize production, thus ensuring China's food security. © 2023 Society of Chemical Industry.

The effects of photoperiod and temperature-related factors on maize leaf number and leaf positional distribution in the field.

Quantifying the effects of various environmental conditions on maize leaf number is essential to understanding the environmental adaptations and population structure of maize plants and for enhancing maize productivity. In this study, seeds of three temperate-adapted maize cultivars, each belonging to different maturity classes, were sown on eight different dates. Sowing dates ranged from the middle of April to early July, which allowed us to cover a wide range of environmental conditions. Random forest regression and multiple regression models with variance partitioning analyses were used to assess the effects of environmental factors on the number of leaves and their distributions on maize primary stems. We demonstrated that the total leaf number (TLN) increased in the three cultivars in the following order: FK139 < JNK728 < ZD958, and variations in TLN for each cultivar were 1.5, 1.76, and 2.75 leaves, respectively. The variation in TLN was ascribed to changes in LB (leaf number below the primary ear), which were higher than variations in LA (leaf number above the primary ear). Variations in TLN and LB were mainly affected by the photoperiod during growth stages V7 to V11, and differences in TLN and LB in response to different photoperiods ranged from 1.34 to 2.95 leaves h-l. Variations in LA was mainly affected by temperature-related factors. Therefore, the results of this study enhanced our current understanding of key environmental conditions that affect maize leaf numbers, and provides scientific support for the benefits of adjusting sowing dates and selecting suitable cultivars to mitigate the effects of climate change on maize production.

Quantitative analysis of maize leaf collar appearance rates.

Phyllochron, the reciprocal of the leaf appearance rate, is a critical genetic parameter in crop models for predicting growth characteristics and yield. Previous studies have shown that existing observations and predictive algorithms do not adequately represent a broad range of cultivars and environments. Here, we conducted a series of experiments in the field to quantify and disentangle the effects of sowing date and cultivar on maize leaf collar appearance (LCA). A bilinear model was found to accurately fit maize LCA (R2adj > 0.99); this model revealed a slower rate of LCA for the first leaves compared to the last leaves. Turning points in the model occurred between the 9.2th and the 13.1th leaf, nearly always below the ear leaf and around a leaf age index (LAI) of 60.0%. The phyllochron before the turning point (PHYLL Ⅰ) was significantly higher than the phyllochron after the turning point (PHYLL Ⅱ) for all three maize cultivars, and PHYLL Ⅰ was approximately two times higher than PHYLL Ⅱ on average. Both PHYLL Ⅰ and PHYLL Ⅱ were significantly affected by sowing date and cultivar. Variations in PHYLL Ⅰ and PHYLL Ⅱ indicated strong plasticity in maize phyllochron at different leaf ranks. The results of this study are critical for improvement of maize management practices and extend the applicability of phyllochron-collar measurements in crop models.

SlRIP1b is a global organellar RNA editing factor, required for normal fruit development in tomato plants.

RNA editing in plant organelles involves numerous C-U conversions, which often restore evolutionarily conserved codons and may generate new translation initiation and termination codons. These RNA maturation events rely on a subset of nuclear-encoded protein cofactors. Here, we provide evidence of the role of SlRIP1b on RNA editing of mitochondrial transcripts in tomato (Solanum lycopersicum) plants. SlRIP1b is a RIP/MORF protein that was originally identified as an interacting partner of the organellar editing factor SlORRM4. Mutants of SlRIP1b, obtained by CRISPR/Cas9 strategy, exhibited abnormal carpel development and grew into fruit with more locules. RNA-sequencing revealed that SlRIP1b affects the C-U editing of numerous mitochondrial pre-RNA transcripts and in particular altered RNA editing of various cytochrome c maturation (CCM)-related genes. The slrip1b mutants display increased H2 O2 and aberrant mitochondrial morphologies, which are associated with defects in cytochrome c biosynthesis and assembly of respiratory complex III. Taken together, our results indicate that SlRIP1b is a global editing factor that plays a key role in CCM and oxidative phosphorylation system biogenesis during fruit development in tomato plants. These data provide important insights into the molecular roles of organellar RNA editing factors during fruit development.

Maize Lodging Resistance with Plastic Film Removal, Increased Planting Density, and Cultivars with Different Maturity Periods.

While plastic film mulching and proper high-density planting are important methods that can improve maize yield, years of accumulated residual film have created soil pollution and degraded soil, and thus has impeded sustainable agriculture development. Here, we compared the stalk and root lodging resistances of three maize cultivars grown at two planting densities both with (FM) and without (NM) plastic film mulch. Our aim was to provide a theoretical basis that may help assure a future of successful no-film planting with increased planting density. The results showed that, compared with FM, the average dry weight per unit length and bending strength of basal internode decreased for all cultivars at both planting densities in the NM treatment. At 9.0 × 104 plants ha-1, the stalk breaking force (SFC) of Xinyu77, KWS9384, and KWS2030 in the NM treatment decreased by 4%, 21%, and 22%, respectively. At 12.0 × 104 plants ha-1, SFC of Xinyu77 and KWS2030 increased by 14% and 1%, respectively, while KWS9384 decreased by 10%. Additionally, the root diameter, length, volume, width, depth, and the vertical root-pulling force of maize decreased. Although the lodging resistance of maize grown without film mulch was lower than that of maize grown with it, those adverse effects can be mitigated by selecting suitable cultivars and by using proper high-density planting and appropriate cultivation measures.

Unaligned Multimodal Sequences for Depression Assessment From Speech.

A growing area of mental health research pertains to how an individual's degree of depression might be automatically assessed through analyzing multimodal-based objective markers. However, when combined with machine learning, this research can be challenging due to the existence of unaligned multimodal sequences and the limited amount of annotated training data. In this paper, a novel cross-modal framework for automatic depression severity assessment is proposed. The low-level descriptions (LLDs) from multiple clues (such as text, audio and video) are extracted, after which multimodal fusion via cross-modal attention mechanism is utilized to facilitate the learning of more accurate feature representations. For the features extracted from each modality, the cross-modal attention mechanism is utilized to continuously update the input sequence of the target mode, until the score of the patient's health questionnaire (PHQ-8) can finally be obtained. Moreover, Self-Attention Generative Adversarial Networks (SAGAN) is employed to increase the amount of training data available for depression severity analysis. Experimental results on the depression sub-challenge dataset of the Audio/Visual Emotion Challenge (AVEC 2017 and AVEC 2019) demonstrate the effectiveness of our proposed method.

Quantitative Relationship Between Solar Radiation and Grain Filling Parameters of Maize.

A quantitative understanding of the factors driving changes in grain filling is essential for effective prioritization of increasing maize yield. Grain filling is a significant stage in maize yield formation. Solar radiation is the energy source for grain filling, which is the ultimate driving factor for final grain weight and grain filling capacity that determine maize yield. Here, we first confirmed the quantitative relationships between grain filling parameters and photosynthetically active radiation (PAR) by conducting field experiments using different shading and plant density conditions and cultivars in 2019 and 2020 in Xinjiang, China. The results showed that with every 100 MJ m-2 increase in PAR, the average grain filling rate (G ave), maximum grain-filling rate (G max), and the kernel weight at the time of maximum grain-filling rate (W max) increased by 0.073 mg kernel-1 day-1, 0.23 mg kernel-1 day-1, and 0.24 mg kernel-1, and the time of maximum grain-filling rate (T max) delayed by 0.91 day. Relative changes in PAR were significantly and positively correlated with relative changes in yield and G ave. With every 1% change in PAR, yield and G ave changed by 1.16 and 0.17%, respectively. From the perspective of grain filling capacity, DH618 was a more shade-resistant cultivar than XY335 and ZD958. It is urgent to breed maize cultivars with low light tolerance and high grain yield in the face of climate change, particularly the decrease in solar radiation.

SlRBP1 promotes translational efficiency via SleIF4A2 to maintain chloroplast function in tomato.

Many glycine-rich RNA-binding proteins (GR-RBPs) have critical functions in RNA processing and metabolism. Here, we describe a role for the tomato (Solanum lycopersicum) GR-RBP SlRBP1 in regulating mRNA translation. We found that SlRBP1 knockdown mutants (slrbp1) displayed reduced accumulation of total chlorophyll and impaired chloroplast ultrastructure. These phenotypes were accompanied by deregulation of the levels of numerous key transcripts associated with chloroplast functions in slrbp1. Furthermore, native RNA immunoprecipitation-sequencing (nRIP-seq) recovered 61 SlRBP1-associated RNAs, most of which are involved in photosynthesis. SlRBP1 binding to selected target RNAs was validated by nRIP-qPCR. Intriguingly, the accumulation of proteins encoded by SlRBP1-bound transcripts, but not the mRNAs themselves, was reduced in slrbp1 mutants. Polysome profiling followed by RT-qPCR assays indicated that the polysome occupancy of target RNAs was lower in slrbp1 plants than in wild-type. Furthermore, SlRBP1 interacted with the eukaryotic translation initiation factor SleIF4A2. Silencing of SlRBP1 significantly reduced SleIF4A2 binding to SlRBP1-target RNAs. Taking these observations together, we propose that SlRBP1 binds to and channels RNAs onto the SleIF4A2 translation initiation complex and promotes the translation of its target RNAs to regulate chloroplast functions.

Solar Radiation Effects on Dry Matter Accumulations and Transfer in Maize.

Solar radiation is the energy source for crop growth, as well as for the processes of accumulation, distribution, and transfer of photosynthetic products that determine maize yield. Therefore, learning the effects of different solar radiation amounts on maize growth is especially important. The present study focused on the quantitative relationships between solar radiation amounts and dry matter accumulations and transfers in maize. Over two continuous years (2017 and 2018) of field experiments, maize hybrids XY335 and ZD958 were grown at densities of 4.5 × 104 (D1), 7.5 × 104 (D2), 9 × 104 (D3), 10.5 × 104 (D4), and 12 × 104 (D5) plants/ha at Qitai Farm (89°34'E, 44°12'N), Xinjiang, China. Shading levels were 15% (S1), 30% (S2), and 50% (S3) of natural light and no shading (CK). The results showed that the yields of the commonly planted cultivars XY335 and ZD958 at S1, S2, and S3 (increasing shade treatments) were 7.3, 21.2, and 57.6% and 11.7, 31.0, and 61.8% lower than the control yields, respectively. Also, vegetative organ dry matter translocation (DMT) and its contribution to grain increased as shading levels increased under different densities. The dry matter assimilation amount after silking (AADMAS) increased as solar radiation and planting density increased. When solar radiation was <580.9 and 663.6 MJ/m2, for XY335 and ZD958, respectively, the increase in the AADMAS was primarily related to solar radiation amounts; and when solar radiation was higher than those amounts for those hybrids, an increase in the AADMAS was primarily related to planting density. Photosynthate accumulation is a key determinant of maize yield, and the contributions of the vegetative organs to the grain did not compensate for the reduced yield caused by insufficient light. Between the two cultivars, XY335 showed a better resistance to weak light than ZD958 did. To help guarantee a high maize yield under weak light conditions, it is imperative to select cultivars that have great stay-green and photosynthetic efficiency characteristics.

Improving photosynthesis to increase grain yield potential: an analysis of maize hybrids released in different years in China.

In this work, we sought to understand how breeding has affected photosynthesis and to identify key photosynthetic indices that are important for increasing maize yield in the field. Our 2-year (2017-2018) field experiment used five high-yielding hybrid maize cultivars (generated in the 1970s, 2000s, and 2010s) and was conducted in the Xinjiang Autonomous Region of China. We investigated the effects of planting density on maize grain yield, photosynthetic parameters, respiration, and chlorophyll content, under three planting density regimens: 75,000, 105,000, and 135,000 plants ha-1. Our results showed that increasing planting density to the medium level (105,000 plants ha-1) significantly increased grain yield (Y) up to 20.32% compared to the low level (75,000 plants ha-1). However, further increasing planting density to 135,000 plants ha-1 did not lead to an additional increase in yield, with some cultivars actually exhibiting an opposite trend. Interestingly, no significant changes in photosynthetic rate, dark respiration, stomatal density, and aperture were observed upon increasing planting density. Moreover, our experiments revealed a positive correlation between grain yield and the net photosynthetic rate (Pn) upon the hybrid release year. Compared to other cultivars, the higher grain yield obtained in DH618 resulted from a higher 1000-kernel weight (TKW), which can be explained by a longer photosynthetic duration, a higher chlorophyll content, and a lower ratio of chlorophyll a/b. Moreover, we found that a higher leaf area per plant and the leaf area index (HI) do not necessarily result in an improvement in maize yield. Taken together, we demonstrated that higher photosynthetic capacity, longer photosynthetic duration, suitable LAI, and higher chlorophyll content with lower chlorophyll a/b ratio are important factors for obtaining high-yielding maize cultivars and can be used for the improvement of maize crop yield.

Prevalence of Intimate Partner Violence and Associated Factors Among Men Who Have Sex with Men in China.

Intimate partner violence (IPV) in the heterosexual population has gained increasing public concern in China, but little is known about it among men who have sex with men (MSM).1 This study aimed to investigate the prevalence of IPV and associated factors among MSM in Chengdu, China. Participants were recruited from a local MSM-friendly health consulting center. This study used the adjusted Intimate Partner Violence Scale among Gay and Bisexual Men (IPV-GBM scale) to capture lifetime IPV experiences including physical, sexual and emotional violence, monitoring, and controlling behaviors. Among 431 participants, 153 (35.5%) reported any IPV experiences, and 119 (27.6%) reported themselves as being the perpetrator. Adjusted logistic regression models revealed that having been engaged in transactional sex was positively associated with victimization through monitoring behaviors (adjusted odds ratio [ORa] = 2.7, 95% confidence interval CI = [1.7, 7.4]) and perpetration of monitoring behaviors (ORa = 3.9, 95% CI = [1.5, 13.3]); drug use was positively associated with victimization through controlling behaviors (unadjusted odds ratio [ORu] = 2.5, 95% CI = [1.2, 5.0]) and emotional violence (ORa = 1.9, 95% CI = [1.0, 3.5]); older age (≥18 years) of first homosexual intercourse was negatively associated with perpetration of physical violence (ORu = 0.3, 95% CI = [0.2, 0.7]) and sexual violence (ORu = 0.4, 95% CI = [0.2, 1.0]); higher self-esteem was negatively associated with both victimization and perpetration of sexual and emotional violence. We found that victimization and perpetration experiences were correlated in all dimensions of IPV. Violence was prevalent among MSM and merits public attention. This study provides more evidence about IPV among Chinese MSM and identifies two significant factors contributing to IPV (self-esteem and age of first homosexual intercourse), which have been overlooked in previous studies. Researchers should take these factors into consideration for interventions developments.

Evaluation of maize lodging resistance based on the critical wind speed of stalk breaking during the late growth stage.

BACKGROUND: The accurate evaluation of the stalk-lodging resistance during the late stage of maize growth can provide a basis for the selection of cultivars, the evaluation of cultivation techniques, and timely mechanical grain harvesting. In this study, the critical wind speed of stalk breaking, plant morphology, stalk mechanical strength, and lodging rate were investigated in 10 maize cultivars to identify the parameters evaluate lodging resistance during the later growth stage of maize. Clarify the relationship with the stalk mechanical strength, critical wind speed of stalk breaking, and natural lodging rate in the field. RESULTS: The results showed that, in the late growth stage, with increasing number of days after physiological maturity, (1) the stalk lodging rate gradually increased, (2) the stalk breaking force and rind penetration strength (RPS) of the third internode above the soil gradually decreased, and (3) the critical wind speed of stalk breaking increased first and then decreased, and was highest at about 16-24 days after physiological maturity. The position of stalk lodging mostly occurred between second and fifth internodes. The torque at the base of maize plant increased as wind speed increased, and the different of torque was excited among different maize cultivars under same wind speed. Furthermore, the stalk lodging rate was significantly negatively correlated with the critical wind speed of stalk breaking. Additionally, the critical wind speed of stalk breaking was significantly positively correlated with the stalk breaking force and the RPS. CONCLUSION: This indicates that the critical wind speed of stalk breaking is a superior way to determine the stalk lodging resistance. These results suggest that, in the late growth stage, the decrease in the stalk mechanical strength is an important reason for the decrease in the critical wind speed of stalk breaking and the increase in the lodging rate.

Marginal superiority of maize: an indicator for density tolerance under high plant density.

Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions. In this study, in order to clarify the response of marginal superiority to maize morphology and plant-density tolerance, field experiments without water and nutrition stress were conducted at Qitai Farm in Xinjiang, China, in 2013-2014 and 2016-2019. The results showed that no more than three border rows of all the cultivars had marginal superiority under high density, about 90% of all the cultivars had no more than two border row that had marginal superiority and a significant negative correlation was observed between marginal superiority and population grain yield (first border row: y = - 2.193x + 213.9, p < 0.05; second border row: y = - 2.076x + 159.2, p < 0.01). Additionally, marginal superiority was found to have a significant positive relationship with plant density (first border row: y = 6.049x + 73.76, p < 0.01; second border row: y = 1.88x + 95.41, p < 0.05) and the average leaf angle above the ear (first border row: y = 2.306x + 103.1, p < 0.01). These results indicated that the smaller the leaf angle above the ear, the weaker the marginal superiority and the higher the grain yield. It suggests that the magnitude of marginal superiority in the border rows can be an indicator for plant-density tolerance under high density. What's more, cultivars with small leaf angle above the ear can be selected to weaken the marginal superiority and improve grain yield under high plant density. Conversely, cultivars with a large leaf angle above the ear can be selected to achieve higher individual yield in intercropping systems with no more than four rows alternated with other crops.