Efficient fossil energy consumption in agricultural systems is a prerequisite for sustainable agricultural production. Fossil energy consumption (EC) in avocado orchard production in Michoacán, Mexico was analyzed. Process analysis was used to estimate both direct and indirect energy required for the various agricultural operations. Data on fuel and inputs used in production were obtained from structured questionnaires completed by 455 growers. Average annual EC was 28,880 MJ∙ha-1, but the data ranged between 5,330 and 76,531 MJ∙ha-1, indicating the co-existence of a great diversity of farming systems. EC in agricultural operations decreased in the following order: fertilization (54.4 %), pest control (39.9 %), weed control (5.6 %) and irrigation (0.2 %). EC in fertilization was positively associated with the economic resources of the growers; and according to recognized fertilization standards, nitrogen fertilizer was applied excessively in 64 % of the orchards. EC in pest control was in the high range reported for fruit-tree crops and, on average, it was 41 % higher in exporting orchards than in those that produce only for the domestic market. EC in avocado production can be significantly reduced by improving fertilization and pest control practices, especially among large- and medium-sized growers.

Microbial dynamics, mineral and total nitrogen content were studied during the composting process of filter cake reactivated with chicken manure. Four substrates with different proportions of filter cake:chicken manure (10:0, 9:1, 7:3 and 5:5 v/v) were tested using 68 liters containers for 87 days. Temperature, total populations of bacteria, fungi, ligninolytic microorganisms, CO2 evolution, total nitrogen, ammonium and nitrate content were the evaluated variables. The addition of chicken manure to stored filter cake increased the populations of bacteria, fungi and ligninolytic microorganisms, showing microbial populations of 9.9, 5.5 and 6.4 log units (ULog), respectively. Substrate 5:5 v/v showed a decrease in NH+4-N (from 947 to 268 mg·kg-1) and an increase in NO-3-N (from 2.7 to 483 mg·kg-1) and in total nitrogen (3.4 to 4.7 %). This proportion of chicken manure and filter cake was better because it was biologically stable (compost) and had the highest content of total nitrogen.

The use of repeated insecticide applications in agricultural crops to control Bemisia tabaci (Genn.) has resulted in resistance problems and environmental pollution. Inputs from plant species are an alternative to reduce this problem. Plants are a source of bioactive chemicals that can have insecticidal, repellent, attractant, anti-feeding or growth regulator effects. The aim of this study was to determine the insecticidal and repellent activity of ethanolic, acetonic and aqueous extracts of both leaves and stems of Pluchea sericea (Nutt.) on Bemisia tabaci (Genn.). The LC50 of each of the extracts on adult whiteflies was estimated using bioassays with the residual film technique. Also, the repellent effect from the LC50 of each extract was evaluated, and the repellency index (RI) was estimated. If RI = 1 the effect is neutral, if RI <1 the effect is repellent and if RI > 1 the effect is attractant. The leaf-ethanol, leaf-water and leaf-acetone extracts showed the lowest LC50 values of 700, 1,190 and 1,250 ppm respectively, indicating high efficiency on B. tabaci, followed by the stem-water extract and lastly the stem-ethanol and stem-acetone extracts showed the least effectiveness. All extracts had repellent action, regardless of the solvent and plant organ at 24 and 48 h. However, water-based extracts may have greater potential for whitefly control in integrated pest management systems because they presented insecticidal and repellent effects, and the solvent is harmless and inexpensive.

Hydroponic systems with nutrient solution recycling provide more efficient water and fertilizer use, but over time it becomes difficult to sustain the nutritional balance and control diseases that attack plant roots, which eventually results in lower yield compared to systems where nutrient solution is not recycled. The aim of this study was to evaluate the yield and earliness of butter lettuce (Cortesana M1 variety) grown with different hydroponic systems and their efficiency in terms of water and nutrient use. A randomized block experimental design with four replicates and three treatments (T) was used: T1: tezontle substrate beds without recycling the drained nutrient solution; T2: tezontle substrate beds with recycling the drained nutrient solution; and T3: floating root system. Yield and earliness variables were measured and also the savings and efficiency in water and fertilizer use were estimated. Data were subjected to analysis of variance and Tukey’s multiple comparisons of means test (P = 0.05). The best yield, earliness and efficiency in water and nutrient use occurred with the floating root system. There were no differences in yield or earliness between the substrate systems with or without nutrient solution recycling.

Hippeastrum, commonly known in Mexico as Mancuernilla, is important in floriculture because of its beautiful flowers; it can be propagated by seeds, bulb separation and twin cataphylls. In Mexico, bulbs are imported from the United States and the Netherlands, meaning high investment costs for nursery growers; therefore, propagation methods are needed to provide inexpensive vegetative material for the commercial production of this ornamental. The objective of this study was to evaluate different bulb cutting methods for the propagation of Hippeastrum. Bulbs (8 cm) were used and nine cutting methods were studied: 1) the whole bulb, 2) basal section, 3) ^ cut in basal section, 4) basal section without central bud, 5) cutting basal section in half, 6) basal section into quarters, 7) longitudinal cut into quarters, 8) longitudinal cut into eighths and 9) basal section into quarters, separating each quarter into five groups of twin cataphylls. When the main bud was preserved, no bulbils were formed; when using the basal section: eliminating the central bud, cutting in half, and cutting into quarters, 5-6 bulbils were obtained; when the entire bulb was used and it was cut longitudinally into four and eight sections, 10 and 13 bulbils were obtained respectively. In contrast, when the basal section was cut into four parts, separating each quarter into five twin-cataphyll groups, 25 bulbils were obtained. It was concluded that Hippeastrum propagation was greater when the basal section of the mother bulb was cut into quarters and each quarter was separated into 5 twin-cataphyll groups.

The objective of this research was to compare the method proposed by Markowitz (mean-variance) and the method proposed by Estrada (mean-semivariance), in the choice of an agricultural portfolio. The data were the returns of five agricultural products for the period 1980-2009; both the covariance matrix and semicovariance matrix were estimated to be used in either method. Later, a size n = 30 simulation of 100 replications was performed, to obtain the yields of each product, thus 100 solutions per method. For comparative purposes, a histogram was constructed; this was completed with the t test concluding that the average portfolio is the same under both methods.

Chickpea downy mildew is one of the most destructive diseases found sporadically in chickpea fields in the counties of Salvador Alvarado and Guasave, Sinaloa, Mexico. The aims of this study were to morphologically characterize the species of Peronospora causing downy mildew in chickpea, and to describe the histological changes induced by the pathogen in chickpea seeds and leaflets at different stages of infection (initial, intermediate and advanced). Samples of healthy and naturally-infected chickpea cv. “Blanco Sinaloa-92” leaflets and seeds were collected for morphological characterization of the pathogen and histological analysis. Cross-sections of leaflets and seeds were obtained with a manual rotary microtome and processed using the safranin-fast green differential staining technique. Morphological characterization indicated that Peronospora ciceris is the causative species of downy mildew symptoms in Sinaloa, Mexico. Histological evidence in leaflets with initial stages of infection showed palisade parenchyma with cell disruption, followed by hypertrophy and rupturing of cells. In addition, abundant coenocytic mycelial growth colonizing the vascular system and causing rupturing of the xylem vessels and phloem sieve tubes was observed. In leaflets with intermediate symptoms, the presence of intercellular mycelium, chloroplast degradation and loss of cell nuclei was detected. Leaflets with advanced symptoms exhibited damage in all tissues, showing massive cell destruction caused by extensive mycelial colonization in the epidermis, mesophyll, phloem and xylem. In seeds, intercellular mycelium was only observed in the embryonic cells.