Tipificación socio-agronómica y energética de productores de maíz en la región Frailesca, Chiapas, México

The identification and characterization of farmers types in the maize agroecosystem is an essential element for the development of effective and sustainable socio-productive strategies. In four municipalities of the Frailesca region in Chiapas, Mexico; maize farmers were typified and their agroecosystem was characterized regarding the criteria: socioeconomic, productive and energy efficiency. Besides, farmers relation to conventional, agro-ecological and mixed production strategies was determined. It was an exploratory socio-agronomic and descriptive research focused on a system approach and energy flows. The sample used was 300 farmers. For data management, descriptive statistics and exploratory multivariate analysis of principal components and clusters were used to construct the typologies. Five types of farmers-groups were identified based on six components that explained 83 % of the total variance. Among these components, the following stood out: "Yield and Efficiency", "Maize profile" (refers to the type of maize and its importance within the system) and "Energy Consumption". The typified groups of farmers were labeled as: "Small farmers", "Major farmers", "Mixed livestock-maize farmers", "Subsistence farmers" and "Maize-stubble producers". All groups are characterized by having small maize areas, but they are considered to have an acceptable energy efficiency, greater than 10 MJ and yields between 2.8 and 4.0 t.ha-1, higher than the average for the state of Chiapas. All groups were efficient in the use of energy, as result of the high productive and economic capacity of the agroecosystem. The maize yield is between 2.8 and 4.0 t.ha-1 and the energy efficiency is higher than 10 MJ. Conventional agriculture management predominates in the region in 86 % of the studied systems.

Evaluation of Changes in Soil Compaction Due to the Passage of Combine Harvester

This paper concerns the results of changes in soil compaction after the passages of combine harvester. The research was done on the maize-stubble; the soil was the mold formed in the sand. The measured parameter was a penetration of resistance in range of depth 0–60 cm. The measurements were done in the ruts after the passages the front and rear wheel of combine harvester. During the experiment two levels of vertical load of wheels were applied – these levels were dependent on filling of grain tank of harvester. Moreover, the influence of the lateral tilt of harvester on the soil compaction was analyzed (the harvester was equipped with the leveling system which allowed to obtain the tilt). The obtained results shows that the increase in vertical load caused greater compaction in ruts. Furthermore, it was found that the passage of tilted harvester caused lower compaction than the harvester without tilt.

Trichothecene Genotype Composition of Fusarium graminearum Not Differentiated Among Isolates from Maize Stubble, Maize Ears, Wheat Spikes, and the Atmosphere in New York

In order to test the hypothesis that the trichothecene genotype composition of local populations of Fusarium graminearum is structured by specific habitats, a collection of 1,407 isolates was obtained from overwintered maize stubble, mature maize ears and wheat spikes, and the atmosphere 1.5 m aboveground during the flowering stage of these crops. These isolates were sampled at three diverse agricultural locations in New York State: namely, Aurora (sampled in 2012 and 2013) in central New York, Belmont (sampled in 2013) in southwestern New York, and Willsboro (sampled in 2013) in northeastern New York. Approximately 100 isolates of F. graminearum from each habitat were collected within a 10-mile2 area in each location. Polymerase chain reaction assays were used to identify three main B-trichothecene genotypes—3-acetyldeoxynivalenol (3-ADON), 15-ADON, or nivalenol (NIV)—based on amplification of portions of Tri3 and Tri12 genes. All but the NIV genotype were detected. The 15-ADON genotype predominated in most locations; frequencies were 92% (652/709) at Aurora, 78% (332/379) at Belmont, and 53% (167/319) at Willsboro. Frequencies of any genotype did not differ in general among the four habits in each location. An exception was in Aurora 2012, where only 5 in 24 3-ADON isolates were found in samplings from the air and grains of both crops. As viewed by the composition of trichothecene genotypes, local populations of F. graminearum appear not to be structured by these four habitats inclusive of pathogenic and saprophytic phases of the fungus life cycle. The similar frequency of 3-ADON and 15-ADON in eastern New York (Willsboro), which is less than 400 km away from the Aurora sampling location in the central area of the state, suggests that regional populations may be differentiated based on selection associated with climatic or landscape features not currently identified.

Stenocarpella maydis and its toxic metabolites: a South African perspective on diplodiosis

Stenocarpella maydis is one of the most prevalent ear and stalk rot pathogens of maize globally, causing reductions of grain quality and yield. Various molecular methods, including polymerase chain reaction (PCR)-based techniques and nucleotide microarrays, have been developed for the identification of S. maydis infestation in maize grain. In addition to diplodiatoxin, new metabolites, namely dipmatol, diplonine and chaetoglobosins K and L, have been isolated from S. maydis infected cultures. S. maydis infected maize is also associated with intoxication in ruminants. Diplodiosis, a nervous disorder of cattle and sheep, results from ingestion of mouldy ears, kernels and maize stubble infected by S. maydis. Although this disease is most common in southern Africa, it has also been reported in Australia, Argentina and Brazil. Diplodiosis is characterised by reluctance of the animals to move, a wide-based stance, incoordination, paralysis and death. Myelin degeneration (status spongiosis) is the only histopathological change observed in affected animals, especially in cases of perinatal mortality. To date, none of the purified S. maydis metabolites has been administered to ruminants in order to reproduce diplodiosis. However, recent studies have focused on investigating the toxicity of the metabolites on cell cultures. Cytotoxicity studies where cultured cells were exposed to the S. maydis metabolites indicated that diplodiatoxin and dipmatol affected the activity of the mitochondrial succinate dehydrogenase enzyme and the overall viability of the cells. More detailed in vitro toxicity studies are still required to elucidate how the currently available S. maydis metabolites influence parameters such as the mechanism of cell death. Development of analytical test methods to quantify and establish the presence and distribution of these mycotoxins in infected maize commodities also needs investigation. It is also critical that the role of S. maydis stalk rot be evaluated as a potential source and cause of diplodiosis.

Vibration Test and Analysis of No-Tillage Planter on the Maize Stubble Surface

In order to improve metering accuracy of air suction type no tillage seeder in maize stubble ground operation, the vibration parameters of air suction seed metering device of the machine are tested and analyzed. Using the method of orthogonal experiment, with forward speed, ditching depth, ridge direction as the influence factors by experimental study on vibration characteristics.The results showed that in no tillage corn field conditions,Stubble height 10-30cm, ridge height is 0-8cm, the soil moisture content 19.78%, The soil temperature 12.7oC. Effects of sowing machine vibration frequency spectrum of 3.46-12.30Hz and 33.50-50.50Hz, the two band spectrum reflects the vibration characteristic of planter operation in the field, can be used as indoor and virtual test selection of reference data. The test results show that: the main factors causing vertical vibration of no tillage seeder metering device is 90o ridge direction, i.e. the surface roughness is greater, causing the vibration of no tillage planter seeding device more. The second is a seeding machine forward speed for 7km/h, i.e., no tillage planter work faster, causing vibration the greater. Finally is the sowing depth, the factors and agronomic seeds, soil fertility, soil humidity etc. Agronomic requirements are closely related, for the smaller vibration effect of no tillage seeder metering device.