Lodging Percentage Research Articles

Caracterización morfoagronómica de poblaciones de maíz criollo (Zea mays L.), provincia de Manabí, Ecuador

Ecuador is a country with a wide genetic diversity of maize and there are populations of native maize conserved by farmers that have not yet been characterized. These genetic resources could be conserved and used in plant breeding programs. The objective of this research was to characterize the morpho-agronomic diversity of 38 populations of native maize from the province of Manabí, Ecuador, using 19 quantitative and 11 qualitative morpho-agronomic descriptors. During the dry season of 2022 (July - December) at the Portoviejo Experimental Station of the National Institute of Agricultural Research (INIAP), plots of 8 m2 were established for each population of native maize, with 0.3 m between plants and 0.8 m between furrows and each furrow was 5 m long. Cluster analysis showed the formation of four groups, where the populations of hard kernels with large ears and soft kernels with short ears were separated into different groups. The quantitative variables ear height, panicle length, percentage of lodging, number of kernels per row and biomass of the inflorescence rachis recorded "D" indices of 0.75, showing themselves as discriminant variables in the formation of the groups, while the most discriminating qualitative variables were kernel type (χ2 = 49.09***, P= 0.742, V= 0.64), kernel color (χ2= 51.955***, P= 0.75, V=0.64), row arrangement (χ2= 18.11*, P=0.56, V=0.39), and kernel surface shape (χ2 = 20.52*, P=0.58, V=0.41). The native maize races identified were Candela, Cubano, Tuxpeño, Tusilla, and Uchima, observing significant genetic diversity in the populations studied. It was concluded that the characterized native maize populations were a valuable genetic resource for the conservation and use of this cereal. Keywords: genotypes, landraces, genetic variability, conservation of genetic resources.

Hybrid Modeling and Management of Lodging in Subtropical Fiber Flax: Optimizing Plant Nutrition for Sustainable Cultivation

ABSTRACT Subtropical fiber flax faces significant challenges due to crop lodging, exacerbated by the high N regimes needed for increased fiber production. This study examines impact of balanced P and K applications under varied N regimes on lodging resistance, fiber yield, and quality of flax. Field experiments with 12 NPK treatments revealed that while 120:19:38 kg N, P, K ha−1 achieved highest plant height, stem-diameter, and fresh-weight while increased lodging percentage and reduced fiber quality when P and K were not balanced. Conversely, balanced P and K applications mitigated negative effects of high N, significantly reducing lodging and enhancing fiber yield, quality. Optimal fiber quality, including fiber length and bundle tenacity, was observed with 90:19:38 kg N, P, K ha−1. The novelty of this study lies in integration of stochastic and ML approaches to develop hybrid models for lodging. By combining LASSO with ANN, NLSVR, and RF techniques, hybrid models outperformed individual models in lodging prediction. Specifically, LASSO-NLSVR provided most accurate predictions due to its nonlinear mapping capabilities. Key predictive factors included fiber content, linear density, and tensile strength at 60 days post-sowing, offering valuable insights for breeders and agronomists to improve flax lodging resistance and fiber quality in subtropical climates.

Propagation of fig (Ficus caricaL.) cuttings under natural rooting at different submergence times

There is a possibility that the time of submersion in natural rooting, with respect to vegetative propagation by fig cuttings, may have a significant effect or differences in the formation and characteristics of the roots. For this reason, the research wascarried out in the Multipurpose Nursery, belonging to the Cota Cota Experimental Centre, under a completely randomised design with factorial arrangement, using a mother plant of more than 12 years old, which is an indication that propagation would be difficult, due to the characteristics of the plant material. The response variables evaluated were: days to root formation, percentage of survival, root length, number of roots, and percentage of lodging. The following results were obtained based on the averages of the data collected in the field research: T9 (lentil water, 48 hours) rooted in 54 days, being the best rooting time. The percentage of survival was influenced by the rooting factor directly, with the natural rooters of lentil water and willow infusion responding much better, with 85.70 and 83.66 % respectively. The rooting and submersion time presented a direct significance in root length, which is equal to 7.60 cm, with treatment 5 (willow infusion, 24 hours). In the variable number of roots, both lentil water and willow infusion achieved 8 and 7 root units respectively, both in a submersion time of 24 hours, and it is also important to note the significance in both factors. Treatment 9 (lentil water, 48 hours) with 90 % was the best average in the variable percent rooting. It was confirmed that the longer the soaking time, the more positive the rooting of the cuttings, depending on the rooting agent used.

Selection based on the phenomenic approach and agronomic ideotic of white oat

AbstractThis work aimed to propose multivariate selection strategies reconciling the agronomic ideotype and vegetation indices to obtain genotypes with high tillering, early cycle, tolerant to lodging, and foliar diseases. The sowing of white oat lines was carried out on April 27, 2023, allocated in an experimental design of blocks augmented with interspersed controls. The regular treatments correspond to 593 lines of white oat and the common treatments were represented by the cultivars URS Olada, URS Altaneira, and IPR Artêmis arranged in four replications. The measurements of variables of agronomic interest took place in each experimental unit as follows: percentage of tillering, days to flowering, percentage of lodging, percentage of leaf rust, percentage of stem rust, and percentage of leaf spots. The phenomic analyses took place through flights carried out with a specialized drone, equipped with a 20 MP resolution camera and standard height (80 m). The best proposed indices were index for reducing the percentage of lodging with normalized green (NG), green–red ratio (IGR), soil color index (SCI), green leaf index (GLI), visible atmospheric resistant index (VARI), green leaf index 2 (GLI2), red–blue (RB), blue green pigment (BGI), normalized red–blue difference index (NRBDI), green–blue ratio, BIM, normalized green–blue difference index (NGBDI), and ExGR; index for reducing days to flowering with brightness index (BI), NRBDI, days to flowering (DF), gray (GRAY), IGR, average intensity (L), normalized red (NR), RGRI, SCI, BGI, BIM, GLI, NGBDI, and NG; and index for reducing the percentage of stem rust with NG, BI, Gray2, GLI2, RGRI, GLI, VARI, BGI, L, NR, RB, and coloration index. Only two lines were selected concomitantly with multivariate indices, line L167 (M5, SA) and L426 (M6, ETMS), that combine lodging tolerance and leaf rust genes.

Effect of planting density on yield and architecture suitability of groundnut (Arachis hypogaea) varieties

A field experiment was conducted during rainy (kharif) seasons of 2018 and 2019 at the research farm of Sri Venkateswara Agricultural College (Acharya N. G. Ranga Agricultural University), Tirupati, Andhra Pradesh, to study the effect of planting density on yield and architecture suitability of groundnut (Arachis hypogaea L.) varieties. The experiment included 4 sowing densities (D1, 33.3 plants/m2; D2, 50 plants/m2; D3, 66.6 plants/m2 and D4, 100 plants/m2) and 3 genotypes with varying architecture (G1, Kadiri 6-erect; G2, Kadiri 9-decumbent 2; and G3, Dharani-decumbent 3). The results showed that across planting densities, Dharani and Kadiri 9 genotypes showed higher architectural traits, structural carbohydrates and kernel yield compared to the Kadiri 6. A significant positive correlation was detected between the lodging percentage and both plant height (r = 0.88**) and internodal length (r = 0.61*). Significant negative correlations, were identified between lodging percentage and several parameters, including leaf thickness (r = -0.92**), specific leaf weight (r = -0.93**), stem diameter (r = -0.79**), specific stem weight (r = -0.97**), number of branches (r = -0.72**), cellulose content (r = -0.80**), and lignin content (r = -0.79**). These findings indicate that the decumbent architecture is optimal for achieving groundnut lodging resistance and kernel yield in high-density planting systems.

Response of maize stalk to plant density on cellulose accumulation by modulating enzymes activities

Hybrids and plant density are the main factors affecting maize lodging resistance, and cellulose plays an important role in lodging resistance. High plant density often decreases the stalk cellulose, but the cause is unclear. Therefore, we hypothesized that enzymatic activity might be the main factor affecting maize cellulose accumulation. For testing this hypothesis, three plant densities （4.5, 9.0 and 13.5 plants m−2） were set up and three maize hybrids （high lodging resistant cultivars: Xianyu 335, Zhengdan 958; low lodging resistant cultivar: Xinyu 41）with different lodging resistance were selected as materials. The results showed that high plant densities reduced the stalk cellulose contents and strength, and hence lodging risk increased. Through logistic curve fitting, we found that the period of rapid accumulation of cellulose in stalks was 10–26 DPV6 (days post 6-leaf stage). Analyse changes of stalk sucrose and related enzyme activity during 10–26 DPV6 showed that with the increase of plant density, the sucrose content of the stalks significantly decreased (P＜0.05), sucrose content began to differ at 16-DPV6. Both sucrose phosphate synthase(SPS) and sucrose synthase(SS) activity of stalks in this stage decreased with the increase of plant densities. At 20 DPV6, there has a great difference in SPS among different plant densities during this period. Compared with 4.5 plants m−2, the decreases for SPS in Xianyu 335 and Zhengdan 958 was lower than Xinyu 41 at 9.0 plants m−2 and 13.5 plants m−2. The SPS for Xianyu 335 decreased by 10.0%− 16.0% and 28.7%− 37.7% at 9.0 plants m−2 and 13.5 plants m−2, respectively. However, the SPS for Xinyu 41 decreased by 24.4%− 27.3% and 40.2%− 50.2%, respectively. At 16 DPV6, there was a large difference in SS among different plant densities, the decreases for SS in Xianyu 335 and Zhengdan 958 was lower than Xinyu 41. Xianyu 335 decreased by 3.6%− 15.9%, 18.8%− 32.7% at at 9.0 plants m−2 and 13.5 plants m−2, respectively. Similarly Xinyu 41 decreased by 18.2%− 26.4% and 31.8%− 50.6%, respectively. Thus, under high plant density, the activities of SS and SPS in maize stalks were decreased, the accumulation and conversion of sucrose into cellulose were inhibited, and the activity of cellulose synthesis-related enzymes in varieties with poor lodging resistance were more sensitive to the increase of density. Therefore, we concluded that higher activity of SS and SPS increased cellulose accumulation and stalk strength in maize varieties with better lodging resistance reduced the lodging percentage under close density conditions.

An improved approach to estimating crop lodging percentage with Sentinel-2 imagery using machine learning

It is imperative to rapidly and precisely acquire crop lodging area and severity for disaster prevention and yield prediction. However, estimation of crop lodging area at a large scale remains challenging due to the relatively low sensitivity of remote sensing signal to the lodging variation, limited availability of remote sensing images, and lodging statistical data. This study proposes a new method for lodging area estimation based on the optimal grid cell of Sentinel-2 and crop lodging percentage, overcoming the limitation of traditional pixel-based mapping approaches that fail to obtain quantitative lodging information. Basing the spatial aggregation method, we analyzed the optimal grid size of Sentinel-2 data for lodging percentage estimation. Then we investigated the spectral response for different lodging percentage levels and analyzed the potential of lodging percentage estimation for Sentinel-2 metrics (including selected spectral bands and their derived vegetation indexes (VIs)). A quantitative model was established between the training set and the Sentinel-2 metrics using the random forest (RF) algorithm. Finally, around 1462.62 ha fields from six counties or districts in Heilongjiang province in China were estimated for lodging percentage. Results indicate that the proposed method can estimate the crop lodging percentage on the testing set with an R2 and RMSE of 0.64 and 25.24, respectively, which can explain around 95 % spatial variation of lodging crop. Moreover, the overall magnitude of reflectance increased with the increase in lodging percentage. Among all Sentinel-2 optimal metrics, the Green, SWIR1, and Red edge 1 bands are the most crucial indicators for lodging percentage estimation. Our results on lodging percentage estimation in the study area indicate that there is more lodging maize in the Meilisidawoerzu district than in other areas. Although typhoons passed over Fuyu and Lindian counties, the lodging percentage in these areas is relatively low. The lodging percentage map has great value in agriculture management and insurance claim.

Spraying Ethephon Effectively Increased Canopy Light Transmittance of Densely Planted Summer Maize, Thus Achieving Synergistic Improvement in Stalk Lodging Resistance and Grain Yield.

Increasing planting density is an effective way to improve maize yield, but high plant populations often cause a lodging problem. This experiment was conducted to investigate the effect of increasing planting density on stalk lodging resistance and grain yield, and to explore the effects on stalk and yield properties of spraying ethephon in densely planted summer maize. The summer maize hybrid, Xundan20 (XD20), was used as experimental material. It was grown by spraying water (CK) or ethephon (E) at BBCH (BASF, Bayer, Ciba-Geigy and Hoechst) 17 under three different planting densities of 60,000 plants ha−1 (L), 75,000 plants ha−1 (M) and 90,000 plants ha−1 (H) in order to explore the possibility of synergistic improvement in stalk lodging resistance and grain yield. The results from this experiment suggested that the gravity center height of densely planted summer maize was significantly increased, the stem diameter, area and number of vascular bundles were significantly decreased and the dry weight per unit internode was significantly decreased, thereby weakening the stalk rind penetration strength and bending performance, resulting in a significant increase in lodging percentage. The ear height was significantly decreased and the SPAD (soil and plant analysis development) and canopy light transmittance were increased after spraying ethephon; then, the internode dry weight per unit length was increased and the stalk rind penetration strength and bending performance were enhanced so as to significantly reduce the lodging percentage and increase the grain yield. The correlation analysis further showed that lodging percentage was significantly negatively correlated with stem diameter, area and number of vascular bundles and stalk bending performance, but there were no strong relationships with grain yield. This suggested that the synergistic improvement in stalk lodging resistance and grain yield was not contradictory. Under the experiment conditions, the effect of spraying ethephon was most significant when the planting density was 90,000 plants ha−1. At the time, the lodging percentage and grain yield were 12.2% and 11,137.5 kg ha−1, which were decreased by 44.6% and increased by 8.0% compared with the control treatment. Scientific chemical regulation could significantly improve the stalk lodging resistance and grain yield of densely planted summer maize.

Nitrogen management improves lodging resistance and production in maize (Zea mays L.) at a high plant density

Lodging in maize leads to yield losses worldwide. In this study, we determined the effects of traditional and optimized nitrogen management strategies on culm morphological characteristics, culm mechanical strength, lignin content, root growth, lodging percentage and production in maize at a high plant density. We compared a traditional nitrogen (N) application rate of 300 kg ha−1 (R) and an optimized N application rate of 225 kg ha−1 (O) under four N application modes: 50% of N applied at sowing and 50% at the 10th-leaf stage (N1); 100% of N applied at sowing (N2); 40% of N applied at sowing, 40% at the 10th-leaf stage and 20% at tasseling stage (N3); and 30% of N applied at sowing, 30% at the 10th-leaf stage, 20% at the tasseling stage, and 20% at the silking stage (N4). The optimized N rate (225 kg ha−1) significantly reduced internode lengths, plant height, ear height, center of gravity height and lodging percentage. The optimized N rate significantly increased internode diameters, filling degrees, culm mechanical strength, root growth and lignin content. The application of N in four split doses (N4) significantly improved culm morphological characteristics, culm mechanical strength, lignin content, and root growth, while it reduced internode lengths, plant height, ear height, center of gravity height and lodging percentage. Internode diameters, filling degrees, culm mechanical strength, lignin content, number and diameter of brace roots, root volume, root dry weight, bleeding safe and grain yield were significantly negatively correlated with plant height, ear height, center of gravity height, internode lengths and lodging percentage. In conclusion, treatment ON4 significantly reduced the lodging percentage by improving the culm morphological characteristics, culm mechanical strength, lignin content, and root growth, so it improved the production of the maize crop at a high plant density.

Effects of paclobutrazol application on plant architecture, lodging resistance, photosynthetic characteristics, and peanut yield at different single-seed precise sowing densities

The key to high-yielding peanut cultivation is the optimization of agricultural production practices. Regulating single-seed precise sowing (SSPS) density and paclobutrazol (Pbz) application concentration are effective practices that increase peanut yield by improving plant architecture, lodging resistance, and photosynthetic characteristics. Therefore, we conducted a two-factor field optimization experiment for the sowing density (D1: 1.95 × 105 plants ha−1, D2: 2.40 × 105 plants ha−1, D3: 2.85 × 105 plants ha−1, and D4: 3.30 × 105 plants ha−1) and Pbz application concentration (P0: 0 mg L−1 and P1: 100 mg L−1). The objective was to optimize agricultural production practices and provide a theoretical basis for high-yielding peanut cultivation by evaluating the effects of sowing density and Pbz application on plant architecture, lodging resistance, photosynthetic characteristics, and yield. The results showed that at the same Pbz application concentration, increasing sowing density increased lodging percentage and reduced leaf photosynthetic capacity. At the same sowing density, Pbz application reduced lodging percentage by decreasing plant height (PH), improving lignin biosynthesis-related enzyme activities, and enhancing stem puncture strength (SPS) and breaking strength (SBS). The paclobutrazol-induced alterations in plant architecture and lodging resistance improved light transmission at the middle and bottom leaf strata, resulting in the increase in relative chlorophyll content and net photosynthetic rate (Pn) of leaves. Furthermore, D3P1 treatment had the highest peanut yield among all treatments. In summary, the production strategy combining the sowing density of 2.85 × 105 plants ha−1 with the application of 100 mg L−1 Pbz was found to be the optimal agricultural production practice for giving full play to production potential and achieving higher peanut yield.

108 Forage Mass and Nutritive Value of Stockpiled Alfalfa-bermudagrass Systems

Abstract The development of newer alfalfa cultivars with improved adaptation to local growing conditions and dual-purpose applications has increased alfalfa incorporation into grass systems in the southern United States. The complementary growth of both species helps to extend the forage production season length, decreasing producer reliance on supplementation. The objective was to determine forage mass (FM) and nutritive value, botanical composition, and structural responses of alfalfa-bermudagrass systems managed under five stockpiling strategies (6-, 8-, 10-, 12- and 14-weeks of accumulation) in Shorter, AL. A randomized complete block design with eight replications was used. Harvested forage samples were manually separated into individual components and placed into 60° C until constant weight, then weighed. Measurements of ground cover, and alfalfa density and persistence were taken prior to plot harvest. There was a treatment × year interaction (P= 0.009) and greater FM was observed for 10- and 12-wks of regrowth (4,279 and 4244 kg DM/ha, respectively) in Year 2. This response was associated with greater (P < 0.001) bermudagrass percentage in the mixture in Year 2 than 1 (averaged 57 vs 23%, respectively). Weeds remained below 4% in both years. There was a direct relationship between increased regrowth period length with leaf shattering and lodging. Over 10-wks of regrowth, percentage of lodging was >30% and rate of leaf shattering doubled. This response directly affected leaf area index observed for the alfalfa-bermudagrass mixtures at 14-wk with a reduction of 30% when compared to 6-wks regrowth (2.6 vs 3.9, respectively). Greater (P < 0.001) digestibility was associated with shorter regrowth period (6-wk), although the values observed ranged from 62 to 87% which represents high nutritive value forage that can meet higher animal requirements. Based on results, stockpiling alfalfa-bermudagrass mixtures using varying accumulation period lengths may be a viable system to provide high quality feed and extend the grazing season length into the fall and winter. This can also be an important strategy aiming to increase diversity and sustainability in forage-based livestock systems.

Effect of Foliar Application time and rates of exogenous salicylic acid on growth and grain yield performances of sorghum [Sorghum bicolor L. Moench

The experiment included two sorghum varieties, four salicylic acid (SA) rates, and three application times in a factorial design. Following foliar application of 0.5 or 1mM salicylic acid (SA), stem borer severity and stem lodging percentage were significantly reduced compared to controls (distilled water). For Meko, applying 0.5mM SA after 30 days of planting resulted in a 15% increase in grain yield above the control. Similarly, the application of 1Mm SA, 15 days after planting, increased the grain yield of ESH-1 by more than 20% than control. When sprayed with 0.5mM SA 30 days after planting, the hybrid ESH-1 produced the maximum dry biomass per plant (210.4g), while plants treated with distilled water produced the lowest dry biomass per plant (154.2 g). Similarly, for Meko, the highest dry biomass per plant (207.5 g) was found in plants sprayed with 0.5mM SA 45 days after planting, while the lowest dry biomass (124.3 g) was found in plants sprayed with distilled water 15 days after planting. So, in the Melkassa area, foliar sprays of 0.5 mM and 1 mM salicylic acid (SA) can boost grain yield of Meko and ESH-1 sorghum genotypes.

Effects of nitrogen fertilizer and chemical regulation on spring maize lodging characteristics, grain filling and yield formation under high planting density in Heilongjiang Province, China

Now, lodging is a major constraint factor contributing to yield loss of maize (Zea mays L.) under high planting density. Chemical regulation and nitrogen fertilizer could effectively coordinate the relationship between stem lodging and maize yield, which significantly reduce lodging and improve the grain yield. The purpose of this study was to explore the effects of chemical regulation and different nitrogen application rates on lodging characteristics, grain filling and yield of maize under high density. For this, we established a field study during 2017 and 2018 growing seasons, with three nitrogen levels of N100 (100 kg ha–1), N200 (200 kg ha–1) and N300 (300 kg ha–1) at high planting density (90 000 plants ha–1), and applied plant growth regulator (Yuhuangjin, the mixture of 3% DTA-6 and 27% ethephon) at the 7th leaf. The results showed that chemical control increased the activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), 4-coumarate:CoA ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD), and increased the lignin, cellulose and hemicellulose contents at the bottom of the 3rd internode, which significantly reduced the lodging percentage. The lignin-related enzyme activities, lignin, cellulose and hemicellulose contents decreased with the increase of nitrogen fertilizer, which significantly increased the lodging percentage. The 200 kg ha–1 nitrogen application and chemical control increased the number, diameter, angle, volume, and dry weight of brace roots. The 200 kg ha–1 nitrogen application and chemical control significantly increased the activities of ADP-glucose pyrophosphorylase (AGPase), soluble starch synthase (SSS) and starch branching enzyme (SBE), which promoted the starch accumulation in grains. Additional, improved the maximum grain filling rate (Vmax) and mean grain filling rate (Vm), which promoted the grain filling process, significantly increased grain weight and grain number per ear, thus increased the final yield.

Effect of altered leaf angle on maize stalk lodging resistance

AbstractIncreasing light intensity in the mid and low canopy can improve maize (Zea mays L.) stalk lodging resistance. Field experiments involving altered leaf angle were designed to explore how leaf angle affects the light distribution within the canopy, stalk carbohydrate accumulation, stalk strength formation, and grain yield. When the leaf area was constant and the average leaf angle was decreased by ∼10° above the ear leaves and increased by ∼25° at the ear leaves and below, the photosynthetically active radiation (PAR) at the ear layer increased by 41–62%, and the interception of PAR (IPAR) below the ear increased by 107–229%. Average cellulose content of the third and fourth internodes increased by 13–21%, whereas lignin content increased by 9–30%. The rind penetration strength (RPS) of the third internode increased by 13–21%, whereas the crush strength (CS) of the fourth internode increased by 15–27%. These changes resulted in a reduction of 6–11% in the lodging percentage. The grain yield increased by 15–27% because of increases in kernel number and kernel weight. Therefore, under close planting, selecting a maize ideotype with upright leaves in the upper canopy and flat leaves in the lower canopy is conducive to rational radiation allocation in the maize canopy. This would facilitate structural carbohydrate accumulation and mechanical strength formation while improving lodging resistance and grain yield.

COMPORTAMIENTO AGRONÓMICO DEL MAÍZ TROPICAL DOSMESANO NATIVO DE TABASCO, MÉXICO BAJO DIFERENTES DENSIDADES DE SIEMBRA.

El maíz dosmesano (Zea mays L.) es un tipo de maíz nativo utilizado en el sistema milpa de Tabasco, México, apreciado por su calidad de tortilla y por su gran adaptación a las condiciones del trópico mexicano. Es necesario generar recomendaciones de manejo agronómico para mejorar su aprovechamiento. El objetivo de este estudio fue evaluar el potencial productivo del maíz tropical dosmesano nativo de Tabasco, México bajo diferentes densidades de población, generadas con variantes de arreglos topológicos de distancia entre surcos (0.8 y 1.0 m), distancia entre matas (0.20 y 0.25 m) y número de semillas por mata (una y dos); adicionalmente, se incluyeron un testigo regional (TR) a 1.0 m entre surcos, 1.0 m entre matas y cuatro semillas/mata, y otro modificado (TRM) con 0.8 m entre surcos, 1.0 m entre matas, cuatro semillas/mata. Se utilizó un diseño experimental de bloques completos al azar con tres repeticiones, con arreglo factorial de tratamientos. Se registraron las variables días después de la siembra a 50 % de floración masculina (50 % FM) y 50 % de floración femenina (50 % FM), altura de mazorca (AM, cm), altura de planta (AP, cm), relación AP/AM, porcentaje de acame (PA), relación (AP/AM)/PA, porcentaje de plantas jorras (PPJ), porcentaje de prolificidad (PP) y rendimiento de grano (RG, kg ha-1). Se detectó interacción significativa de distancia entre surcos × número de semillas/mata para RG (P ≤ 0.01) y PPJ (P ≤ 0.01). El mayor RG (3869 kg ha-1) se observó en 1.0 m de distancia entre surcos y dos semillas por mata, con 80,000 plantas ha-1, y superó a TR que rindió 2198 kg ha-1. El mayor PPJ, 73 %, se observó en distancia entre surcos de 0.8 m y dos semillas por mata. Hubo triple interacción significativa en AP (P ≤ 0.01) y AM (P ≤ 0.01), ambas con distancia entre surcos de 0.8 m, distancia entre matas de 0.2 m y una semilla por mata, con media de 2.67 y 1.26 m, respectivamente. Existió efecto simple significativo del número de semillas por mata para PP (P ≤ 0.05), con 17 y 4 %, con una y dos semillas por mata, respectivamente. No se detectaron efectos significativos para 50 % FM, 50 % FF, PA, en la relación AP/AM y (AP/AM)/PA (P > 0.05). El RG observado indica alto potencial del cultivo bajo alta densidad poblacional, en comparación con el sistema tradicional de siembra.

Quantitative effects of solar radiation on maize lodging resistance mechanical properties

Abstract Lodging adversely affects maize (Zea mays L.) yields and quality, especially under low sunlight conditions. Here, we investigated the effects of different levels of solar radiation on maize lodging. To study the quantitative effects of different solar radiation on the lodging resistant mechanism of maize stalks, we chose two maize cultivars, Xianyu 335 (XY335) and Zhengdan 958 (ZD958), and grew them in two regions that receive the most abundant solar radiation in Xinjiang and Ningxia China in 2018 and 2019. Maize plants were exposed to different shade levels (15 % (S1), 30 % (S2), 50 % (S3), and natural light as the control (CK)) and different planting densities (4.5 × 104 (D1), 7.5 × 104 (D2), 9 × 104 (D3), 10.5 × 104 (D4), and 12 × 104 (D5) plants ha− 1) to create different solar radiation conditions. The results showed that lodging percentage was significantly negatively correlated with the stalk bending strength (SBS), rind penetration strength (RPS), vertical root pulling resistance (VRPR), dry weight per unit length (DWUL), the cellulose and lignin content and grain yield which significantly decreased with decreasing total intercepted photosynthetically active radiation (TIPAR). Quantitative analysis showed that for every 1 MJ m- 2 reduction in TIPAR, the SBS and RPS decreased by 0.0667 N and 0.075 N, DWUL and the content of cellulose and lignin of maize stalk significantly decreased with decreasing TIPAR, by 0.88 mg cm− 1, 0.3 mg g- 1 and 0.06 mg g− 1, respectively. Lodging percentage was significantly negatively correlated with TIPAR, the lodging percentage increased by 0.17 % with a decrease in TIPAR of 1 MJ m- 2. Comparison of cultivars revealed that the rate of decrease in SBS, RPS, VRPR, DWUL and the cellulose and lignin content were greater for XY335 than for ZD958, indicating that the stalk strength of XY335 was more sensitive than ZD958 to decreasing levels of TIPAR. However, SBS, RPS, DWUL and the cellulose and lignin content of XY335 were higher than ZD938 and the lodging percentage of XY335 was lower than ZD958 which meant that XY335 had a stronger stalk strength to resistance to lodging. This is important for understanding lodging resistance and developing cultivars suited to different solar radiation conditions in different regions, as well as to changing solar radiation conditions induced by global climate change.

In situ evaluation of stalk lodging resistance for different maize (Zea mays L.) cultivars using a mobile wind machine

BackgroundStalk lodging is an impediment to improving profitability and production efficiency in maize. Lodging resistance, a comprehensive indicator to appraise genotypes, requires both characterization of mechanical properties in laboratory and investigation of lodging percentage in field. However, in situ characterization of maize lodging resistance still remains poor. The aim of this study was to develop an indicator, named cumulative lodging index (CLI), based on lodging percentages at different wind speeds for evaluating lodging resistance for different maize cultivars, and to evaluate the accuracy and reliability of this method.ResultsDifferent cultivars showed different patterns of lodging percentage along with wind speeds. The failure wind speed (FWS) for maize ranged between 16 and 30 m s−1 across cultivars. The CLI differed between maize cultivars and showed favorable reliability (i.e. nRMSE of 5.38%). Mechanical properties of the third internode did not vary significantly between cultivars. Significant differences in the reduction index (RI) of wind speed sheltered by maize canopy were found between cultivars.ConclusionOur findings implied that mobile wind machine is powerful in reproducing wind disaster that induce crop lodging. The newly-built CLI was demonstrated to be a more robust indicator than mechanical properties, FWS, and RI when evaluating lodging resistance in terms of both reliability and resolution. This study offers a new perspective for evaluating in situ lodging resistance of crops, and provides technical support for accurate identification of lodging-resistant phenotypic traits.

QUANTIFYING LODGING PERCENTAGE, LODGING DEVELOPMENT AND LODGING SEVERITY USING A UAV-BASED CANOPY HEIGHT MODEL

Abstract. Unmanned Aerial Vehicles (UAVs) are increasingly used, and open new opportunities, in agriculture and phenotyping because of the flexible data acquisition. In this study the potential of ultra-high spatially resolved UAV image data was investigated to quantify lodging percentage, lodging development and lodging severity of barley using Structure from Motion techniques. The term lodging is defined as the permanent displacement of a plant from the upright position. Traditionally lodging quantification is based on observations that need, and vary with observers in the field. An objective threshold approach was proposed in this study to improve the accuracy in lodging determination. Across breeding trials, manual reference measurements and UAV based lodging percentage showed a very high correlation (R2 = 0.96). In addition, the multi-temporal lodging percentage development was used to estimate the recovery rate and to determine the influence of different lodging events. Based on the parameter lodging percentage an approach was developed that allowed the assessment of lodging severity, an information that is important to estimate the yield impairment. Lodging severity can be used for insurance applications, precision farming and breeder research. This trait, together with differentiated recovery are novel traits next to lodging severity that will aid the selection for genetic lines.

Quantifying Lodging Percentage and Lodging Severity Using a UAV-Based Canopy Height Model Combined with an Objective Threshold Approach

Unmanned aerial vehicles (UAVs) open new opportunities in precision agriculture and phenotyping because of their flexibility and low cost. In this study, the potential of UAV imagery was evaluated to quantify lodging percentage and lodging severity of barley using structure from motion (SfM) techniques. Traditionally, lodging quantification is based on time-consuming manual field observations. Our UAV-based approach makes use of a quantitative threshold to determine lodging percentage in a first step. The derived lodging estimates showed a very high correlation to reference data (R2 = 0.96, root mean square error (RMSE) = 7.66%) when applied to breeding trials, which could also be confirmed under realistic farming conditions. As a second step, an approach was developed that allows the assessment of lodging severity, information that is important to estimate yield impairment, which also takes the intensity of lodging events into account. Both parameters were tested on three ground sample distances. The lowest spatial resolution acquired from the highest flight altitude (100 m) still led to high accuracy, which increases the practicability of the method for large areas. Our new lodging assessment procedure can be used for insurance applications, precision farming, and selecting for genetic lines with greater lodging resistance in breeding research.

LOSSES IN WHEAT CROP AS A FUNCTION OF THE WATER CONTENT OF THE GRAINS AT HARVEST

The objective was to study the harvest point for the wheat crop, associated maximum grain yield and productive components with different harvest moisture and losses on natural drying in the field with different water levels in grain. The treatments consisted of the following crop moisture levels (on wet basis) of the grains: 27.9 (point of full physiological maturity), 22.6; 19.9; 18.1; 15; and 12.9%, evaluating the number of spikelets per spike, number of voids grains, number of grains per spike and per spikelet, percentage of lodging, thousand grain mass, number of ears per meter, hectoliter mass, and yield. The largest wheat yield was obtained with the grain harvest at physiological maturity point, decreasing linearly until natural drying to 13% (on a wet basis).