Stalk Mechanical Strength Research Articles

Identification and Analysis of the Mechanism of Stem Mechanical Strength Enhancement for Maize Inbred Lines QY1.

Enhancing stalk strength is a crucial strategy to reduce lodging. We identified a maize inbred line, QY1, with superior stalk mechanical strength. Comprehensive analyses of the microstructure, cell wall composition, and transcriptome of QY1 were performed to elucidate the underlying factors contributing to its increased strength. Notably, both the vascular bundle area and the thickness of the sclerenchyma cell walls in QY1 were significantly increased. Furthermore, analyses of cell wall components revealed a significant increase in cellulose content and a notable reduction in lignin content. RNA sequencing (RNA-seq) revealed changes in the expression of numerous genes involved in cell wall synthesis and modification, especially those encoding pectin methylesterase (PME). Variations in PME activity and the degree of methylesterification were noted. Additionally, glycolytic efficiency in QY1 was significantly enhanced. These findings indicate that QY1 could be a valuable resource for the development of maize varieties with enhanced stalk mechanical strength and for biofuel production.

Research Progress on Mechanical Strength of Rice Stalks.

As one of the most important food crops in the world, rice yield is directly related to national food security. Lodging is one of the most important factors restricting rice production, and the cultivation of rice varieties with lodging resistance is of great significance in rice breeding. The lodging resistance of rice is directly related to the mechanical strength of the stalks. In this paper, we reviewed the cell wall structure, its components, and its genetic regulatory mechanism, which improved the regulatory network of rice stalk mechanical strength. Meanwhile, we analyzed the new progress in genetic breeding and put forward some scientific problems that need to be solved in this field in order to provide theoretical support for the improvement and application of rice breeding.

Optimizing Row Spacing Increases Stalk Lodging Resistance by Improving Light Distribution in Dense Maize Populations

Dense planting effectively increases maize yield while increasing stalk lodging risk. Appropriate row spacing can improve the maize population structure and stalk lodging resistance, but its physiological ecological mechanisms and interaction with planting density are unclear. Here, a two-year field experiment to determine the joint effects of row spacing and planting density on maize stem characteristics and the quantitative relationship of the light condition within a maize population with stalk lodging resistance indicated that the stalk mechanical strength showed a quadratic function relationship with photosynthetically active radiation (PAR), whereas the lodging rate showed an exponential function relationship with basal light transmittance (LT). Further, the basal LT was significantly positively correlated with basal internode thickness, dry weight per unit stem length (DWUL), mechanical and cortical tissue thickness, and lignin and cellulose contents. Increasing the planting density decreased the basal LT and PAR; correspondingly decreased the basal internode thickness, DWUL, mechanical and cortical tissue thickness, lignin and cellulose contents, and stalk mechanical strength; and increased the lodging rate, while increasing row spacing did the opposite. Thus, optimizing the row spacing enhanced the lodging resistance through LT and PAR improvement of the lower part of the population and further increased the grain yield by optimizing the yield components. The appropriate row spacing varied with the planting density. The proper strategy for high stalk lodging resistance and grain yielding under this experimental condition was 67,500 plants ha−1 density with 60 + 60 cm equal row spacing.

Characteristics and candidate genes associated with excellent stalk strength in maize (Zea mays L.).

Lodging is a major problem in maize production, which seriously affects yield and hinders mechanized harvesting. Improving stalk strength is an effective way to improve lodging. The maize inbred line Jing2416 (J2416) was an elite germplasm in maize breeding which had strong stalk mechanical strength. To explore the characteristics its stalk strength, we conducted physiological, metabolic and transcriptomic analyses of J2416 and its parents Jing24 (J24) and 5237. At the kernel dent stage, the stalk rind penetrometer strength of J2416 was significantly higher than those of its two parents in multiple environments. The rind thickness, sclerenchyma tissue thickness, and cellulose, hemicellulose, and lignin contents of J2416 were significantly higher than those of its parents. Based on the significant differences between J2416 and 5237, we detected metabolites and gene transcripts showing differences in abundance between these two materials. A total of 212 (68.60%) metabolites and 2287 (43.34%) genes were up-regulated in J2416 compared with 5237. The phenylpropanoid and glycan synthesis/metabolism pathways were enriched in metabolites and genes that were up-regulated in J2416. Twenty-eight of the up-regulated genes in J2416 were involved in lignin, cellulose, and hemicellulose synthesis pathways. These analyses have revealed important physiological characteristics and candidate genes that will be useful for research and breeding of inbred lines with excellent stalk strength.

Effects of Nitrogen Fertilizer Management on Stalk Lodging Resistance Traits in Summer Maize

Stalk lodging in Huang-Huai-Hai summer maize is a serious problem that reduces maize yields and precludes the use of mechanical grain harvesting equipment. In order to determine the effect of nitrogen management on the lodging resistance of maize stalk, three nitrogen application rates of 150, 250, and 350 kg ha−1 (denoted as N150, N250, and N350), and different nitrogen application periods (sowing, 6-leaf, 12-leaf, silking) were set. Plant morphology, stalk mechanical strength, total carbohydrate, nitrogen content, and yield were measured in the different treatments. The results showed that as the nitrogen application rate increased and nitrogen application was postponed, the stalk breaking force, plant height, ear height, center of gravity height, stalk basal internode diameter, rind penetration strength, content of carbohydrate, and total N of maize stalk also increased. The stalk lodging resistance was improved by the increased nitrogen application rate and postponed nitrogen application by increasing the stalk material accumulation and mechanical strength. The nitrogen application rates had no significant effect on grain yield. Under N250 and N350, the treatments with no base fertilizer significantly decreased the kernel number per ear, reflected in some in grain yield. In summary, under the conditions of integrated water and fertilizer drip irrigation and fractional nitrogen fertilizer applications, increased nitrogen fertilizer input can stimulate the growth of high-quality maize populations, significantly improve stalk lodging resistance in the early growth stage, delay stalk senescence, improve stalk strength and influence stalk composition in later growth stages. Based on the summer maize grain yield and stalk lodging resistance, under N250 treatment, a base fertilizer combined with topdressing at the 12-leaf and silking stages was beneficial to the growth of summer maize.

Lignin metabolism regulates lodging resistance of maize hybrids under varying planting density

Hybrids and planting density are the main factors affecting maize lodging resistance. Here, we aimed to elucidate the mechanism of the regulation of maize lodging resistance by comparing two hybrids at various planting densities from the perspective of lignin metabolism. Our results showed that compared to lodging-susceptible hybrid Xundan 20 (XD20), lodging-resistant hybrid Denghai 605 (DH605) showed a lower center of gravity and culm morphological characteristics that contributed to the higher lodging resistance of this hybrid. Lignin content, activities of key lignin synthesis-related enzymes and G-, S- and H-type monomer contents were significantly higher in hybrid DH605 than in hybrid XD20. Stalk mechanical strength, lignin accumulation and enzyme activity decreased significantly with increasing planting density in the two hybrids. While G-type monomers first decreased with increasing planting density but then remained stable, S-type monomers showed a decreasing trend, and H-type monomers showed an increasing trend. Correlation analysis showed that lodging rate was significantly correlated with plant traits and lignin metabolism. Therefore, maize hybrids characterized by high lignin accumulation, high lignin synthesis-related activities, high S-type monomer content, low center of gravity, high stem puncture strength, high cortical thickness, and small vascular bundle area are more resistant to lodging. High planting densities reduce stalk lignin accumulation, relevant enzyme activities and mechanical strength, thereby, ultimately increasing the lodging rate significantly.

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

BackgroundThe 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.ResultsThe 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.ConclusionThis 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.

Device for determining critical wind speed of stalk breaking to evaluate maize lodging resistance

The accurate evaluation of the lodging resistance of maize plants can provide a basis for the breeding of lodging-resistant cultivars and the regulation of cultivation measures. However, the traditional methods for evaluating maize lodging resistance in terms of plant morphology and stalk mechanical strength have certain limitations. The objective of this research was to develop a device for determining the critical wind speed of maize stalk breaking. The device used a centrifugal fan to supply airflow and was powered by a frequency conversion motor. The frequency converter adjusted the motor speed and thus adjusted the wind speed. The wind speed decreased first and then increased with increasing height above the outlet of the device, and maximum wind speed can reach 40 m/s. This device was convenient for transportation in the field, has a low cost, and can quickly, accurately, and objectively determine the lodging resistance. Field tests showed that the device ran stably for a long time. The coefficient of variation of three repeated measurements was between 1.5% and 4.8% for four maize cultivars. The new device can measure the critical wind speed of maize lodging and identify the lodging resistance for different maize cultivars, cultivation practices, and plant health conditions, and can thus overcome barriers to measuring the maize lodging resistance under natural wind conditions. Keywords: maize, stalk lodging, critical wind speed, turbofan, measuring device, wind pressure DOI: 10.25165/j.ijabe.20201305.6033 Citation: Xue J, Ming B, Wang K R, Xie R Z, Hou P, Li S K. Device for determining critical wind speed of stalk breaking to evaluate maize lodging resistance. Int J Agric & Biol Eng, 2020; 13(5): 1–7.

Key indicators affecting maize stalk lodging resistance of different growth periods under different sowing dates

The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields. Here, we established five different sowing dates to create different conditions for maize growth. We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology, moisture content, mechanical strength and dry matter, and the relationship between stalk breaking force and these indicators during the silking stage (R1), milk stage (R3), physiological maturity stage (R6), and 20 days after R6. Plant height at R1 positively affected stalk breaking force. At R3, the coefficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance. At R6, the key indicators were the coefficient of the center of gravity height and plant fresh weight. After R6, the key indicator was the coefficient of the center of gravity height. The crushing strength of the fourth internode correlated significantly and positively with the stalk breaking force from R1 to R6, which indicates that crushing strength is a reliable indicator of stalk mechanical strength. These results suggest that high stalk strength and low ear height benefit lodging resistance prior to R6. During and after R6, the coefficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.

Traits of plant morphology, stalk mechanical strength, and biomass accumulation in the selection of lodging-resistant maize cultivars

• There is no correlation in current maize cultivar’s resistance to stalk or root lodging. • Stalk breakage is primarily affected by dry weight per unit length during grain filling. • Vertical root pulling resistance is primarily affected by the ratio of root depth to width. • High ratios of shoot fresh weight to vertical root pulling resistance increase maize root lodging risk. Lodging resistance is a major desired trait in modern maize breeding. Identifying parameters to evaluate lodging resistance could help crop breeders develop maize cultivars with improved lodging resistance. Thirty-four summer maize cultivars currently planted in China were grown in 2017 and 2018 in order to identify relationships between stalk and root lodging resistance and to analyze the main reasons for differences in lodging resistance between maize cultivars. Twenty-five lodging resistance indicators, including aspects of morphology, dry matter, moisture content, and the mechanical strength of the stalk and root, were investigated at silking and 35 d after silking. The experiments showed that the ratio of shoot fresh weight to vertical root pulling resistance (VRPR) was a better indicator of root lodging potential than VRPR alone. Stalk breaking force was not associated with VRPR and was significantly positively correlated with shoot fresh weight/VRPR. Classification of the 34 cultivars revealed that resistance to stalk and root lodging were not correlated. Correlation and regression analyses revealed that approximately 63 % of the breaking force was explained by the average dry weight per unit length (DWUL) of the basal three internodes, ear height, and fresh weight of the basal three internodes at silking. At 35 d after silking, approximately 88 % of the difference in breaking force was explained by the plant height, ear ratio, crush strength (CS) of the fourth internode, average DWUL and fresh weight per unit volume (FWUV) of the basal three internodes. The main indicator affecting VRPR was the ratio of root depth to width at 35 d after silking. Therefore, an important strategy for increasing maize lodging resistance is to breed cultivars with high internode DWUL, low ear position, and deep roots.

Device for determining critical wind speed of stalk breaking to evaluate maize lodging resistance

The accurate evaluation of the lodging resistance of maize plants can provide a basis for the breeding of lodging-resistant cultivars and the regulation of cultivation measures. However, the traditional methods for evaluating maize lodging resistance in terms of plant morphology and stalk mechanical strength have certain limitations. The objective of this research was to develop a device for determining the critical wind speed of maize stalk breaking. The device used a centrifugal fan to supply airflow and was powered by a frequency conversion motor. The frequency converter adjusted the motor speed and thus adjusted the wind speed. The wind speed decreased first and then increased with increasing height above the outlet of the device, and maximum wind speed can reach 40 m/s. This device was convenient for transportation in the field, has a low cost, and can quickly, accurately, and objectively determine the lodging resistance. Field tests showed that the device ran stably for a long time. The coefficient of variation of three repeated measurements was between 1.5% and 4.8% for four maize cultivars. The new device can measure the critical wind speed of maize lodging and identify the lodging resistance for different maize cultivars, cultivation practices, and plant health conditions, and can thus overcome barriers to measuring the maize lodging resistance under natural wind conditions. Keywords: maize, stalk lodging, critical wind speed, turbofan, measuring device, wind pressure DOI: 10.25165/j.ijabe.20201305.6033 Citation: Xue J, Ming B, Wang K R, Xie R Z, Hou P, Li S K. Device for determining critical wind speed of stalk breaking to evaluate maize lodging resistance. Int J Agric & Biol Eng, 2020; 13(5): 1–7.

Ethephon Improved Stalk Strength of Maize (Zea Mays L.) Mainly through Altering Internode Morphological Traits to Modulate Mechanical Properties under Field Conditions

Stalk strength is critical for reducing maize stalk lodging and maintaining grain yield. Ethephon has been widely applied to molding compact plant-type to reduce the lodging risk in maize production. However, there is little information on how ethephon regulates internode mechanical properties to improve maize stalk strength. Multiyear field experiments (2013–2017) were conducted to determine the effects of foliar-applied ethephon on summer maize internode morphological, chemical and mechanical characteristics. The hypothetical structural equation model was used to analyze the contribution of ethephon-induced changes of internode morphological and chemical traits to stalk mechanical strength. Ethephon significantly reduced the basal internode length, while increasing internode diameters and breaking resistance. Meanwhile, ethephon significantly increased the ratio of structural dry matter to total dry matter and the amount of structural dry matter per unit length and volume. Mechanical assays suggested that ethephon significantly altered geometric properties and increased the maximum bending moment, maximum failure force, while depressing the material properties. Furthermore, correlation and path analyses revealed strong correlations and significant contribution of internode morphological properties to stalk mechanical strength, respectively. These results support the conclusion that ethephon-induced morphology alteration played a major role in improving maize internode strength.

Dual Application of Ethephon and DCPTA Increases Maize Yield and Stalk Strength

Core Ideas Combined treatment with ethephon and DCPTA enhanced stalk mechanical strength of maize. Combined treatment with ethephon and DCPTA improved the post‐anthesis dry matter accumulation of maize. Combined treatment with ethephon and DCPTA improved the grain yield of maize. The combination of ethephon (2‐chloroethyl phosphonic acid, ETH) and 2‐diethylaminoethyl‐3,4‐dichlorophenylether (DCPTA) has been used in maize (Zea mays L.) production in Northeast China, but limited information is available on the effectiveness of ETH+DCPTA. In this study, field experiments were conducted with two maize hybrids, ZhengDan 958 (‘ZD958’) and DongNong 254 (‘DN254’), which were planted at a density of 75,000 plants ha−1, to study the influence of ETH, DCPTA, and ETH+DCPTA on stalk quality (rind penetration strength [RPS], stalk bending strength [SBS], dry weight per unit, cross‐sectional area, and rind thickness), photosynthetic characteristics, bleeding sap, dry matter accumulation (DMA), and yield. Ethephon significantly reduced the lodging rate, plant height, ear height, and center of gravity of both maize hybrids and increased the RPS, SBS, dry weight per unit, cross‐sectional area, and thickness over the 2 yr. Ethephon also significantly decreased the leaf area index (LAI), chlorophyll content (SPAD value), net photosynthetic rate (Pn) and bleeding sap levels and accelerated leaf senescence, which ultimately decreased the yields. Although the application of DCPTA tended to increase the LAI, Pn, and bleeding sap levels and delayed leaf senescence, the plant height, ear height and the center of gravity also increased markedly, resulting in poorer stalk lodging resistance and higher lodging rate. Greater green leaf area, photosynthetic ability and bleeding sap levels and delayed leaf senescence in response to ETH+DCPTA mainly contributed to the increased postanthesis DMA. Thus, the application of ETH+DCPTA could provide a stable method for increasing the maize grain yield.

Correction to: Effect of paclobutrazol, a potential growth regulator on stalk mechanical strength, lignin accumulation and its relation with lodging resistance of maize

In the original publication of the article, the Table 3 was wrongly published. The correct Table 3 is provided here.

Effect of paclobutrazol, a potential growth regulator on stalk mechanical strength, lignin accumulation and its relation with lodging resistance of maize

Effect of paclobutrazol, a potential growth regulator on stalk mechanical strength, lignin accumulation and its relation with lodging resistance of maize