Cross-Sectional Geometry Predicts Failure Location in Maize Stalks

Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when high winds induce bending moments in the stalk which exceed the bending strength of the plant. Previous biomechanical models of plant stalks have investigated the effect of cross-sectional morphology on stalk lodging resistance (e.g., diameter and rind thickness). However, it is unclear if the location of stalk failure along the length of stem is determined by morphological or compositional factors. It is also unclear if the crops are structurally optimized, i.e., if the plants allocate structural biomass to create uniform and minimal bending stresses in the plant tissues. The purpose of this paper is twofold: (1) to investigate the relationship between bending stress and failure location of maize stalks, and (2) to investigate the potential of phenotyping for internode-level bending stresses to assess lodging resistance. Results: 868 maize specimens representing 16 maize hybrids were successfully tested in bending to failure. Internode morphology was measured, and bending stresses were calculated. It was found that bending stress is highly and positively associated with failure location. A user-friendly computational tool is presented to help plant breeders in phenotyping for internode-level bending stress. Phenotyping for internode-level bending stresses could potentially be used to breed for more biomechanically optimal stalks that are resistant to stalk lodging. Conclusions: Internode-level bending stress plays a potentially critical role in the structural integrity of plant stems. Equations and tools provided herein enable researchers to account for this phenotype, which has the potential to increase the bending strength of plants without increasing overall structural biomass.

Kinetics of potassium release from soil amended with clinoptilolite zeolite and maize stalks biochar

A laboratory incubation experiment in a completely randomized design with three replications was carried out for 90 days to test the effect of zeolite and biochar application to calcareous sandy loam soil on potassium forms distribution and its release rate. The treatments included (1) Absolute control (C), (2) 10 g kg-1 zeolite (Z1), (3) 20 g kg-1 zeolite (Z2), (4) 10 g kg-1 biochar (B1), and (5) 20 g kg-1 biochar (B2). After incubation period, the concentrations of soluble, exchangeable, and non-exchangeable K and the release rate of K to 0.01 M CaCl2 during 200 min (10 successive extractions for soil samples of 20 min for each using CaCl2 solution) were determined. Results showed that zeolite application increased the soluble and exchangeable K concentrations. However, amending soil with biochar had a positive effect on all K forms. Addition of zeolite or biochar increased the cumulative K release. The parabolic diffusion, power function and Simple Elovich models described the kinetics of K release to CaCl2 solution well from all the soil treatments. Zeolite and maize stalks biochar may have an effective role in improvement of K availability and release in the calcareous sandy loam soil as well as may aid in increasing the ability of this soil to supply the different crops with K.

Maíz y balché. Una revisión de la iconografía de los murales de Tulum

In this paper we present a review about the murals located in the Temples of the Descending God (Temple 5) and the Frescos (Temple 16) at the pre-Columbian city of Tulum, Quintana Roo. We first study some of the characters dressed as gods, as Chahk, K’awil, Quetzalcóatl, and Xólotl. Secondly, we analyze the ritual paraphernalia, mostly composed of ceramic objects in the form of effigy urns, incense burners, idols, containers with offerings of corn in different preparations, and large jars used to contain liquids, presenting correspondences with the archaeological record. Afterwards, we analyze the intertwined serpents, as well as the vegetal elements that we identify with the flower and fruits of balché tree. Finally, these data are integrated in order to interpret the meaning of the Tulum murals in relation to the practice of bending over the maize stalks in the autumn, and also to the first fruits harvest, which coincides with the flowering of the balché tree and the beginning of the harvest of tajonal honey in Yucatán.

A Global Screening Assay to Select for Maize Phenotypes with a High Tolerance or Resistance to Fusarium verticillioides (Sacc.) Nirenberg Rots

Fusarium verticillioides (Sacc.) Nirenberg (Fv) causes rots in maize around the world and produces mycotoxins that contaminate grains, making this species a significant health concern for both animals and humans. One of the best approaches to address rots is to identify highly tolerant or resistant genotypes that can be used for genetic improvement. The aim of the study was to evaluate dose-response assays to tolerance or resistance for Fv rots throughout the maize life cycle. These tests assessed the effects of Fv during post-germination development and the seedling (V2) stage by seed infection, the plantlet (V4) stage by substrate infection, and in the reproductive phase in maize stalks (R2 stage) and ears (R6 stage) by R1 stage inoculation. In all assays, the doses were effective at distinguishing contrasting phenotypes. Severity, root fresh weight, and aerial length were the most informative parameters at the V2 and V4 stages. Evaluation of the stalk necrosis area between and within the internodes of susceptible genotypes revealed significant differences among doses, and a positive correlation between necrosis and conidia concentration was observed in internodes. Injecting eight million conidia in the ear was sufficient for selecting different phenotypes. A total of 85% of the genotypes conserved their same capacity to respond to Fv infection throughout the maize life cycle, so that screening at the early vegetative stage (e.g., V2) could be useful for distinguishing contrasting phenotypes in the reproductive stage. Implementing these screening assays in a maize breeding program could be valuable for classifying the degrees of resilience of maize germplasms to Fv rots. This global screening has the potential to be employed to select against other Fusarium species.

Yield response of a polycropping system with maize to fermented foliar fertilizers

Anaerobically fermented foliar fertilizers (FFF) are made of local plant or animal inputs. The impact of four different FFF formulations on the output of an intercropping system with fava bean, maize, and squash was assessed in the Toluca Valley, Central Mexico. A fertilizer made of cow manure and fermented agave cactus juice had an elevated N and P content and resulted in the highest maize output. A fertilizer made of cow manure and maize stalks contained most K and delivered the highest squash yield. A FFF made of cow manure and stinging nettle delivered the highest fava bean output. There are no ideal formulations of FFF, but their formulation depends on available resources and treated crops.

Coronatine Enhances Stalk Bending Resistance of Maize, Thickens the Cell Wall and decreases the Area of the Vascular Bundles

Coronatine (COR) is a phytotoxin produced by the pathogen Pseudomonas syringae, it has a structure similar to that of jasmonates (JAs), but it is much more active as a plant growth regulator. The goal of this study was to gain more insight into the effect and the mechanism of COR effects on stalk characteristics are related lodging resistance of maize. The agronomic traits, stalk ultrastructure, and endogenous hormones in maize stalks were studied in field trails and greenhouses, using hybrid cultivar “Xianyu 335” (XY335), “Zhengdan 958” (ZD958) and inbred line B73 as materials in 2018 and 2019. Different concentration of COR were sprayed onto maize foliar surfaces at the seven-expanded-leaves (V7) stage. Foliar application with 10 µmol L−1 of COR at the V7 stage decreased plant and ear height, increased weight and diameter of the basal internodes, and increased penetration strength and stalk bending resistance. Compared to the control treatment, in COR-treated plants, salicylic acid (SA) and jasmonic acid (JA) were decreased significantly in stalks. The treatment of 10 µmol L−1 of COR enhanced lignin accumulation, the integrity, and the thickness of cell walls in maize stalks in the early stages of stem growth in the inbred line B73, as revealed by autofluorescence microscopy and scanning electron micrographs. Our results indicated that COR improved stalk bending resistance of maize not only by optimizing stalk morphological characteristics, but also by altering hormone levels, which may led to greater lignin accumulation, thickens cell wall, and decreased the area of vascular bundles.

Are Maize Stalks Efficiently Tapered to Withstand Wind Induced Bending Stresses?

Stalk lodging (breaking of agricultural plant stalks prior to harvest) results in millions of dollars in lost revenue each year. Despite a growing body of literature on the topic of stalk lodging, the structural efficiency of maize stalks has not been investigated previously. In this study, we investigate the morphology of mature maize stalks to determine if rind tissues, which are the major load bearing component of corn stalks, are efficiently organized to withstand wind induced bending stresses that cause stalk lodging.945 fully mature, dried commercial hybrid maize stem specimens (48 hybrids, ∼2 replicates, ∼10 samples per plot) were subjected to: (1) three-point-bending tests to measure their bending strength and (2) rind penetration tests to measure the cross-sectional morphology at each internode. The data were analyzed through an engineering optimization algorithm to determine the structural efficiency of the specimens.Hybrids with higher average bending strengths were found to allocate rind tissue more efficiently than weaker hybrids. However, even strong hybrids were structurally suboptimal. There remains significant room for improving the structural efficiency of maize stalks. Results also indicated that stalks are morphologically organized to resist wind loading that occurs primarily above the ear. Results are applicable to selective breeding and crop management studies seeking to reduce stalk lodging rates.HighlightMaize stem morphology was investigated through an optimization algorithm to determine how efficiently their structural tissues are allocated to withstand wind induced bending stresses that cause stalk lodging.