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Mechanical defoliation of sugar cane plants (Saccharum spp.) will provide leaves that can be used as fodder. The effect of partial mechanical defoliation on sucrose content, enzyme activities and agronomic parameters of sugar cane is still unknown. We investigated how sucrose accumulation, activities of sucrose phosphate synthase, soluble acid invertase, sucrose synthase, neutral invertase, brix grades, purity grade, moisture content, fibre content, maturity index and reduced sugars of two commercial sugar cane plants (Mex 69-290 and Mex 57-473) were affected in a field experiment. The concentration of sucrose in stems of partial defoliated plants was not significantly different from that found in intact plants. Agronomic parameters and enzyme activities were not different in defoliated plants compared with intact plants except for the moisture content which was higher in defoliated plants than in intact ones. These results indicated that sugar cane plants could be partially defoliated without changing sucrose production and agronomic parameters while providing leaves that could be used as fodder.

Summary Field germination of Acacia angustissima (Mill.) Kuntze, a N2-fixing tree whose bark is traditionally extracted for tannins used in the leather industry, takes up to 55 days and the percentage of germination is generally less than 20%. Abrasion, dry or wet heat, or immersing the seeds in different concentrations of sulphuric acid, chloric acid or hydrogen peroxide for different lengths of time, were tested as germination enhancers. The application of dry heat resulted in < 37% germination, less than the 44% found for untreated control seeds. The application of wet heat for ≤ 30 s and abrasion for 1200 s resulted in 69% germination. Immersing seeds in concentrated H2SO4 for 900 s resulted in 77% germination while diluting H2SO4 or longer exposure to concentrated H2SO4 decreased it. Immersing the seeds in concentrated or diluted H2O2 also increased germination, but to a lesser extent than when immersed in H2SO4. We found that the exposure of seeds of A. angustissima to concentrated H2SO4 for 900 s appeared to be the best technique to stimulate their germination; the treatment gave the largest percentage of germination in the shortest time, the technique is easy to apply and many seeds can be treated at once.

The activities of sucrose-phosphate synthase (SPS), sucrose synthase (SUSY), neutral invertase (NI) and soluble acid invertase (SAI) regulates sucrose activity in sugarcane were studied. Micropropagated sugarcane plants were obtained from callus cultures of four Mexican commercially available sugarcane varieties characterized by differences in sugar production, and activities of SPS, SUSY, NI, SAI and concentrations of sucrose were monitored in the sugarcane stem. The results indicated that sucrose accumulation was positively and significantly related to an increase in activity of SPS and SUSY and negatively to a reduction in activity of SAI and NI (P

Extracts of neem (Azadirachta indica A.) and mata-raton (Gliricidia sepium) leaves were used as insect repellent during organic cultivation of tomato plants (Solanum lycopersicum) and were compared with untreated plants or plants treated with lambda-cyhalothrin (chemical treatment). The best developed tomato plants were found in the Gliricidia treatment, while difference between other treatments were small. The number of different species of macrofauna found on tomato plants were similar in different treatments, except for corn rootworm (Diabrotica spp.) found in the Gliricidia treatment, but not in other treatments. It was found that leaf extract of G. sepium stimulated tomato growth and altered the leaf and fruit characteristics. This was most likely due to its action as a growth regulator and/or an inductor of changes in the tomato growth regulation, but not due to its action as an insect repellent. Consequently, leaf extract of G. sepium could be used to stimulate tomato development.

Organic fertilization and crop association are two agroecological management practices that have the potential to optimize land use in horticultural production. The objective of this study was to evaluate the effect of Bokashi and Bokashi amended with Vermicompost Leachate (VL) on the growth, yield and quality of jalapeno pepper ( Capsicum annuum L.) and onion ( Allium cepa L.) in monoculture and intercropping cultures. This work was conducted under rainfed conditions in the community of Santa Rosa el Oriente, a municipality of Trinity, Chiapas. A randomized complete block design in a split plot arrangement with six treatments and four replicates by treatment was used. Bokashi significantly increased the number of leaves and plant height in onion (37 and 62%) and jalapeno pepper (133 and 94%) compared with the control plants. In jalapeno pepper and onion, the content of capsaicin and soluble solids was 41 and 42% higher with the application of Bokashi plus VL, respectively. In onion, Bokashi increased the polar and equatorial diameters and bulb weight by 28, 69 and 269%, respectively, and its yield increased from 6.4 to 21.0 t ha -1 . The land equivalent ratio (LER) was 1.34 to 1.55, which indicated that intercropping was advantageous on monoculture, regardless of the fertilization type. Therefore, the application of Bokashi and crop association favored the yield and quality of jalapeno pepper and onion with an efficient use of the land. La fertilizacion organica y la asociacion de cultivos son dos practicas de manejo agroecologico con el potencial de optimizar el uso de la tierra en la produccion horticola. El objetivo de este estudio fue evaluar el efecto de Bokashi y Bokashi adicionado con Lixiviado de Vermicomposta (LV) sobre el crecimiento, rendimiento y calidad de chile jalapeno ( Capsicum annuum L.) y cebolla ( Allium cepa L.) cultivados en monocultivo y en policultivo. El experimento se realizo bajo condiciones de temporal en la comunidad Santa Rosa el Oriente, La Trinitaria, Chiapas. Se utilizo un diseno de bloques completos al azar con un arreglo de parcelas divididas con seis tratamientos y cuatro repeticiones por tratamiento. Bokashi incremento significativamente el numero de hojas y la altura de la planta en cebolla (37 y 62%) y chile jalapeno (33 y 94%) en comparacion con las plantas control. En chile jalapeno y cebolla el contenido de capsaicina y solidos solubles fueron 41 y 42% mas altos con la aplicacion de Bokashi adicionado con VL, respectivamente. En cebolla Bokashi incremento 28, 69 y 269% los diametros polar y ecuatorial y el peso del bulbo. Con la aplicacion de Bokashi el rendimiento de cebolla incremento de 6.4 a 21 t ha -1 . Se obtuvo una relacion equivalente de tierra (RET) de 1.34 a 1.55, indicando que el policultivo fue ventajoso sobre el monocultivo, indistintamente del tipo de fertilizacion. Por lo tanto, la aplicacion de Bokashi y la asociacion de cultivos favorecieron el rendimiento y la calidad de chile jalapeno y cebolla con un eficiente uso de la tierra.

Hypericum silenoides Juss. 1804 is an important medicinal plant used in Mexico, but the bacterial community associated with it is unknown. The bacterial communities in the rhizosphere and roots of H. silenoides were isolated and identified by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) and ribosomal types were determined by amplified ribosomal rDNA restriction analysis (ARDRA) and 16S rRNA gene sequences. Sixty-six strains were obtained from roots of H. silenoides and 37 were isolated from the rhizosphere. ERIC fingerprinting distinguished 63 genetic patterns with 44 being unique and the remaining 19 containing 59 strains. Eighteen representative strains were distinguished with ARDRA analysis. 16S rRNA gene sequence analysis revealed that the bacteria isolated from the roots and rhizosphere of H. silenoides belonged to the genera Acinetobacter, Enterobacter, Pseudomonas, Sphingobium, Stenotrophomonas, Agrobacterium, Pantoea and Serratia. The largest number of isolates (30) belonged to the genus Agrobacterium. Richness and diversity of bacteria was higher on the roots than in the rhizosphere of H. silenoides.

The objective of this study was to investigate the effect of vermicompost, worm-bed leachate (WBL) and Glomus mosseae, an arbuscular mycorrhizal fungi (AMF), on growth of lemongrass ( Cymbopogon citratus (DC.) Stapf). A response surface methodology, i.e . a three-level Box Benhen design with three repetitions and three blocks, was applied to optimize biomass production, essential oil yield and its composition. Application rates of Glomus mosseae were 0, 1 or 2 g plant -1 , vermicompost 0, 5 or 10 g plant -1 and WBL 0, 10 and 20%. The AMF had no significant effect on the variables tested, but vermicompost had a significant effect on essential oil yield and WBL on essential oil yield, myercene concentration and shoot dry weigh (p G. mosseae , 5.0 g vermicompost and 20% worm-bed leachate would yield 0.797% essential oil of which 62.6% was citral.

In a previous laboratory experiment, extracts of neem (Azadirachta indica A. Juss.) and Gliricidia sepium Jacquin, locally known as mata-raton, used to control pests on crops, inhibited emissions of CO(2) from a urea-amended soil, but not nitrification and N(2)O emissions. We investigated if these extracts when applied to beans (Phaseolus vulgaris L.) affected their development, soil characteristics and emissions of carbon dioxide (CO(2)) and nitrous oxide (N(2)O) in a greenhouse environment. Untreated beans and beans planted with lambda-cyhalothrin, a commercial insecticide, served as controls. After 117days, shoots of plants cultivated in soil amended with urea or treated with lambda-cyhalothrin, or extracts of neem or G. sepium were significantly higher than when cultivated in the unamended soil, while the roots were significantly longer when plants were amended with urea or treated with leaf extracts of neem or G. sepium than when treated with lambda-cyhalothrin. The number of pods, fresh and dry pod weight and seed yield was significantly higher when bean plants were treated with leaf extracts of neem or G. sepium treatments than when left untreated and unfertilized. The number of seeds was similar for the different treatments. The number of nodules was lower in plants fertilized with urea, treated with leaf extracts of neem or G. sepium, or with lambda-cyhalothrin compared to the unfertilized plants. The concentrations of NH(4)(+), NO(2)(-) and NO(3)(-) decreased significantly over time with the lowest concentrations generally found at harvest. Treatment had no significant effect on the concentrations of NH(4)(+) and NO(2)(-), but the concentration of NO(3)(-) was significantly lower in the unfertilized soil compared to the other treatments. It was found that applying extracts of neem or G. sepium leaves to beans favored their development when compared to untreated plants, but had no significant effect on nitrification in soil.

A response surface technique was used to analyze the effect of Glomus fasciculatum, Pseudomonas fluorescens and worm-bed leachate (WBL) on growth, yield and characteristics of tomato (Lycopersicon esculentum Mill). The treatments combined inoculation with or without P. fluorescensor G. fasciculatum and the application of WBL at 20% (v/v) each day or every three days. Plant height, number of leaves and yield of tomato fruits was not affected by the factors studied. However, plants with foliar application of WBL each day developed wider stems than those with an application every three days. The pH of the fruits was lower when WBL was applied every three days compared to a daily application. The soluble solids content of the fruits was higher when WBL was applied daily compared to those sprayed every three days. Plant development was not affected by addition of P. fluorescens, G. fasciculatum or WBL, but WBL changed fruit characteristics.

The effects of different inorganic fertilizers and rhizobial inoculation on shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content of Acaciella angustissima (Mill.) Britton & Rose were investigated in the laboratory. Seedlings were grown in a climate chamber in glass tubes containing sterilized mixture of vermiculite and peat moss, and treated with combinations of nitrogen (N) at 45 mg plant¹, phosphorus (P) at 30 mg plant¹, potassium (K) at 20 mg plant¹ and inoculated with the bacterium Sinorhizobium mexicanum. The combined applications of N, P or K to uninoculated plants increased shoot height and dry weight as compared to the unamended plantlets. The tannin content in uninoculated plants was highest when amended with P+K. Treatment had a significant effect on plant growth, nodulation and tannin content varied. The plants treated with P + K + S. mexicanum had significantly longer shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content in comparison with unamended plants. It was found that N reduced number of nodules, tannin content and nitrogenase activity of A. angustisisma. As such, farmers should refrain from applying N fertilizer, but could apply P and K to maximize tannin production in A. angustissima. Se investigaron en el laboratorio los efectos de diferentes fertilizantes inorgánicos y la inoculación rizobial sobre la altura de planta, peso seco total de planta, peso seco de raíz, el número de nodulos, el nitrógeno total de la planta, la actividad de la nitrogenasa y el contenido de ácido tánico de Acaciella angustissima (Mili.) Britton & Rose. Las plántulas fueron crecidas en una cámara climática en tubos de vidrio conteniendo una mezcla de vermiculita y turba, y tratadas con las combinaciones de nitrógeno (N) en 45 mg planta"¹, fósforo (P) en 30 mg planta"¹, potasio (K) en 20 mg planta"¹ e inoculado con la bacteria Sinorhizobium mexicanum. La combinación de las aplicaciones de N, P o K en plantas sin inocular incrementa la altura y el peso seco de planta en comparación con las plantas sin tratamiento. El contenido de taninos en plantas no inoculadas fue el más alto cuando suplementamos con P+K. El tratamiento tuvo un efecto significativo sobre el crecimiento de planta, modulación y el contenido de tanino variado. Las plantas tratadas con P + K + S. mexicanum tuvieron significativamente mayor altura de planta, peso seco total de planta, peso seco de raíz, el número de nodulos, nitrógeno total de planta, actividad de la nitrogenasa y contenido de taninos en comparación con las plantas sin suplementar. Fue encontrado que el N reduce el número de nodulos, el contenido de taninos y la actividad de la nitrogenasa de A. angustisisma. Como tal, los agricultores deberían abstenerse de aplicar el fertilizante de N, pero podrían aplicar P y K para maximizar la producción de tanino en A. angustissima.

El objetivo del trabajo fue evaluar el efecto de dos hongos micorrizicos arbusculares (HMA) a diferentes concentraciones de fosforo sobre la sobrevivencia y el crecimiento de plantulas de pina {Ananas comosus (L.) Merr.) obtenidas por micropropagacion. Las plantulas se multiplicaron masivamente en cultivos in vitro y se aclimataron gradualmente bajo un esquema de estres por temperatura en tres etapas secuenciales. Los efectos de los HMA y el fosforo no fueron significativos sobre la sobrevivencia y la altura de las plantulas, sin embargo, Glomus claroideum estimulo que las plantulas tuvieran mayor numero de hojas y peso seco. Los resultados sugieren que la altura de las plantulas fue mayor cuando fueron cultivadas con G. claroideum y 0,9 mM de fosforo.

The survival rate, shoot and root dry mass, shout number, plant growth, stem height and diameter, number of leaves and root length were measured in micropropagated plantlets of Alpinia purpurata (Red ginger) inoculated with Azospirillum sp. 11B and Azotobacter sp. Pachaz 008 at 10(7), 10(8) and 10(9) cells cm(-3) using a complete randomized experimental design. Inoculation ofA. purpurata plantlets with the Azospirillum sp. 11B or Azotobacter sp. PACHAZ 008 strains induced larger stem diameter, root dry mass, number of shoots and increased their survival rate from 77 to 100% compared to plantlets without inoculation, while other plant characteristics were not affected.

Los programas para obtener nuevos genotipos de caña de azúcar (Saccharum officinarum) duran de 10 a 15 años y la etapa de selección es la que consume más tiempo. Por tanto, se realizó un estudio para determinar la relación entre las características de los cultivos de callos y variables agronómicas de plantas derivadas de callos de cuatro genotipos de caña de azúcar cultivados en México. Se encontró que el peso fresco de los callos se correlacionó (0.464; p #8804;0.001) con el tallo industrializable, con el número de entrenudos (0.420; p #8804;0.0001) y número de tallos (0.441; p #8804;0.001). El contenido de sacarosa en los callos se correlacionó con la longitud del tallo industrializable (0.653; p #8804;0.001) y el diámetro de los entrenudos (0.479; p #8804;0.001). El peso fresco y el contenido de sacarosa en los callos son dos características de los cultivos in vitro que deben estudiarse con más genotipos antes de usarse para seleccionar genotipos de caña de azúcar en programas de mejoramiento.

La caña de azúcar es un cultivo muy importante debido al valor económico de sus productos. Es importante que la caña de azúcar tenga alto rendimiento, esto es, que acumule cantidades apreciables de azúcar. Para determinar la importancia relativa de los factores morfológicos y bioquímicos implicados en la regulación de la acumulación de sacarosa en el tallo de caña de azúcar (Saccharum spp), se investigaron las correlaciones bioquímicas y morfológicas de la acumulación de sacarosa en vitroplantas de cuatro variedades comerciales diferentes. No se observó relación entre la morfología y el nivel de acumulación de sacarosa. El nivel y el tiempo de acumulación de sacarosa en el tallo completo y dentro de los entrenudos individuales se correlacionó con la actividad de la invertasa ácida soluble (IAS). Una alta actividad de IAS previno, en parte, la acumulación de sacarosa. La baja actividad de la IAS no fue suficiente para explicar la acumulación de sacarosa en las variedades que almacenan altas concentraciones de sacarosa. Las mayores diferencias en la acumulación de sacarosa entre las variedades comerciales se atribuyeron a la diferencia entre las actividades de IAS y sacarosa fosfato sintetasa (SFS), siempre que la concentración de la IAS sea inferior a su nivel crítico. Este resultado no es inesperado, debido a que la ruta del transporte para la acumulación implica la hidrólisis y resíntesis de la sacarosa.

Resumen en español: "Se evaluó el efecto de la fertilización orgánica y la asociación de cultivos en la producción y calidad de chile jalapeño (Capsicum annum) y cebolla (Allium cepa) en la comunidad de Santa Rosa El Oriente, La Trinitaria, Chiapas. Se estableció una parcela experimental en la que se evaluó el tipo de fertilización (sin fertilización, con bocashi y con bocashi + lixiviado de humus de lombriz), y la asociación de cultivos (en unicultivo y asociados), bajo un diseño de parcelas divididas en bloques al azar con 4 repeticiones. Los resultados mostraron que la fertilización con bocashi incrementó significativamente la altura y el número de hojas; en cebolla y chile con 37% y 133% más hojas, y 62% y 94% más altura que el control, respectivamente. No se observó un efecto significativo de la asociación de cultivos ni de la aplicación foliar del lixiviado de humus en estas variables del crecimiento. El índice equivalente de tierra (IET) fue >1 indistintamente del tipo de fertilización. El largo, ancho y peso de chile jalapeño no varió significativamente entre tratamientos, sin embargo, el contenido de capsaicina tuvo un incremento de 41% con aplicación de bocashi + foliar que en el testigo. En cebolla el abono orgánico incrementó 28, 69 y 269% el diámetro polar, diámetro ecuatorial y peso del bulbo, respectivamente, y no tuvo efecto en el contenido de ácido pirúvico. La fertilización con bocashi incrementó la respiración, la biomasa microbiana y la fosfatasa ácida en la rizosfera de ambas especies. La relación beneficio/costo tuvo valores >1 en cebolla, 1 en la asociación. Se encontró que la aplicación de bocashi y la asociación de chile jalapeño y cebolla favorecieron la producción y calidad de ambos cultivos, as como el uso eficiente del suelo. "