Edgar Omar Rueda-Puente

FIELD EVALUATION OF THE RELATIONSHIP BETWEEN CHLOROPHYLL CONTENT IN BASIL LEAVES AND A PORTABLE CHLOROPHYLL METER (SPAD-502) READINGS

A hand-held SPAD-502 chlorophyll meter provides rapid and nondestructive measures of chlorophyll content. Integrating this meter into basil production can reduce costs and may improve basil quality. This study determined the relationship between SPAD-502 and the leaf chlorophyll (total, a, b). Over 500 leaf samples were collected from a field study conducted in 2006. Comparisons between chlorophyll contents and meter readings showed that SPAD meter readings were positively correlated to actual chlorophyll content. Regression analysis SPAD readings should be corrected by leaf area. Findings suggest that SPAD meter readings can be used as a tool to improve Basil quality and for assessing the relative chlorophyll content during the growing season.

Effects of plant growth promoting bacteria and mycorrhizal on Capsicum annuum L. var. aviculare ([Dierbach] D'Arcy and Eshbaugh) germination under stressing abiotic conditions.

Capsicum annuum var. aviculare to Tarahumara and Papago Indians and farmers of Sonora desert is a promising biological and commercial value as a natural resource from arid and semiarid coastal zones. Traditionally, apply synthetic fertilizers to compensate for soil nitrogen deficiency. However, indiscriminate use of these fertilizers might increase salinity. The inoculation by plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) represents an alternative as potential bio fertilizer resources for salty areas. Seeds ecotypes from four areas of Sonora desert (Mazocahui, Baviacora, Arizpe, La Tortuga), in order to inoculate them with one species of PGPB and AMF. Two germination tests were carried out to study the effect of salinity, temperature regime (night/day) and inoculation with PGPB and AMF growth factors measured on germination (percentage and rate), plant height, root length, and produced biomass (fresh and dry matter). The results indicated that from four studied ecotypes, Mazocahui was the most outstanding of all, showing the highest germination under saline and non-saline conditions. However, the PGPB and AMF influenced the others variables evaluated. This study is the first step to obtain an ideal ecotype of C. a. var. aviculare, which grows in the northwest of México and promoting this type of microorganisms as an efficient and reliable biological product. Studies of the association of PGPB and AMF with the C. a. var. aviculare-Mazocahui ecotype are recommended to determine the extent to which these observations can be reproduced under field conditions.

Effect of Klebsiella pneumoniae and Azospirillum halopraeferens on the growth and development of two Salicornia bigelovii genotypes

Growth and development of 2 pickleweed (Salicornia bigelovii Torr.) genotypes, a local wild type and cultivar, SOS-10, were studied under field conditions. When inoculated with the previously selected and cultivated native strains of Klebsiella pneumoniae and Azospirillum halopraeferens, the 2 pickleweed genotypes exhibited increases in some of the growth and development parameters measured, such as weight, plant length and biochemical characteristics, including total protein, ash and total lipid content in selected plant parts. Our findings suggest that yields of both genotypes of S. bigelovii, under field conditions, can be enhanced by the application of K. pneumoniae or A. halopraeferens strains. The potential usefulness of S. bigelovii for agricultural producers in coastal semi-arid zones has been shown elsewhere; our findings suggest that the establishment and growth of this halophyte can be experimentally improved using beneficial bacteria as auxiliary biofertilisers.

Effect of Pseudomonas putida on growth and anthocyanin pigment in two poinsettia (Euphorbia pulcherrima) cultivars.

Pseudomonas putida is plant growth promoting rhizobacteria (PGPR) that have the capacity to improve growth in plants. The purpose of this study was to determine growth and anthocyanin pigmentation of the bracts in two poinsettia Euphorbia pulcherrima cultivars (Prestige and Sonora Marble) using three strains of P. putida, as well as a mixture of the three (MIX). Comparison with the control group indicated for the most part that Prestige grew better than the Sonora Marble cultivars with the PGPR strains. Prestige with the MIX strain grew better compared to control for the number of cyathia (83 versus 70.4), volume of roots (45 versus 35 cm3), number of leaves (78 versus 58), and area of leaf (1,788 versus 1,331 cm2), except for the number of flowers (8.8 versus 11.6). To the naked eye, coloration of plants appeared identical in color compared to the control group. For all plants with P. putida strains, there was less anthocyanin pigment, but biomass was always greater with PGPR strains. Nevertheless, to the naked eye, the coloration of the plants appeared identical in color compared to the control group. This is the first study reporting the positive effects of P. putida rhizobacteria treatments on growth of poinsettia cultivars.

Changing environmental conditions and applying organic fertilizers in Origanum vulgare L.

Any improvement in agricultural systems that results in higher production should also reduce negative environmental impacts and enhance sustainability. The aim of this research was to investigate the effect of two different production systems, one open-field and the other shade-enclosure with four bocashi doses, in order to find the best environmental option in terms of yield, physiological and morphometric characteristics in one oregano (Origanum vulgare L.) cultivar. In this study a completely randomized block design was used with four replications and evaluated for photosynthetic and transpiration rate, stomatal conductance, chlorophyll, leaf area and temperature, aerial and roots fresh and dry biomass, fresh and dry yield. The results showed that oregano adapted best to the shade-enclosure with increase yield of fresh and dry leaf weight of 165% and 118%, respectively, when compared to open-field. Also, higher doses of bocashi improved yield in both environments but more so in shade-enclosure. Soil moisture retention was higher in shade-enclosure which was reflected in physiological variables for soil matric potential, transpiration, stomatal conductivity, photosynthesis being significantly higher in shade-enclosure compared to open-field, thus improving yield. It seems that oregano plants can be grown and perform better under shade-enclosure than open-field and bocashi is a suitable organic fertilizer.

SPATIAL AND TEMPORAL VARIABILITY OF SOIL FERTILITY IN TERRACED PASTURES

A study was conducted to quantify temporal and spatial variables relative to soil test variability and to propose practices for improving soil sampling in terraced pastures. We sampled along a strip crossing multiple microreliefs (by-strips) and along a microrelief crossing fertilizer treatments. Soil samples were analyzed for pH and plant available nitrogen (N), phosphorus (P), and potassium (K). Temporal variability was consistently greater than spatial variability across the soil fertility parameters tested. Variation among pastures was negligible; however, terrace channels had an impact on soil fertility variability. The two sampling methodologies complemented each other to provide a clear picture about the spatio-temporal dynamics of nutrients in terraced pastures. Some recommendations that could improve soil sampling precision in terraced pastures include allowing substantial precipitation to occur between grazing and sampling and to collect soil cores representing all microrelief areas except terrace channels to form a composite sample.

Baseline study of morphometric traits of wild Capsicum annuum growing near two biosphere reserves in the Peninsula of Baja California for future conservation management

BackgroundDespite the ecological and socioeconomic importance of wild Capsicum annuum L., few investigations have been carried out to study basic characteristics. The peninsula of Baja California has a unique characteristic that it provides a high degree of isolation for the development of unique highly diverse endemic populations. The objective of this study was to evaluate for the first time the growth type, associated vegetation, morphometric traits in plants, in fruits and mineral content of roots, stems and leaves of three wild populations of Capsicum in Baja California, Mexico, near biosphere reserves.ResultsThe results showed that the majority of plants of wild Capsicum annuum have a shrub growth type and were associated with communities consisting of 43 species of 20 families the most representative being Fabaceae, Cactaceae and Euphorbiaceae. Significant differences between populations were found in plant height, main stem diameter, beginning of canopy, leaf area, leaf average and maximum width, stems and roots dry weights. Coverage, leaf length and dry weight did not show differences. Potassium, sodium and zinc showed significant differences between populations in their roots, stems and leaves, while magnesium and manganese showed significant differences only in roots and stems, iron in stems and leaves, calcium in roots and leaves and phosphorus did not show differences. Average fruit weight, length, 100 fruits dry weight, 100 fruits pulp dry weight and pulp/seeds ratio showed significant differences between populations, while fruit number, average fruit fresh weight, peduncle length, fruit width, seeds per fruit and seed dry weight, did not show differences.ConclusionsWe concluded that this study of traits of wild Capsicum, provides useful information of morphometric variation between wild populations that will be of value for future decision processes involved in the management and preservation of germplasm and genetic resources.

Crecimiento de plántulas de tomate (Solanum lycopersicum L.) tratadas con humato de vermicompost

The humate of vermicompost is a stimulant that improves the quality and productivity of crops and allows the total or partial elimination of chemical fertilizers, contributing to organic, ecological and sustainable agriculture. The objective of this study was to evaluate the effect of different concentrations of vermicompost humates (1/10, 1/20, 1/30 v/v and a control-distilled water-) on the growth of Solanum lycopersicum seedlings grown on affected soils by salinity. The experiment was carried out using a completely randomized design with four repetitions per treatment of 40 seedlings each. At 24 days after transplantation, height of seedlings, stem diameter, number of leaves, fresh and dry weight of aerial part and root were measured. The results showed significant differences between treatments and all the variables showed higher values ​​in the dilution of 1/30 (v/v), followed by the dilutions 1/20 and 1/10, showing lower values ​​in the control. The percentage value of increase in the dilution of 1/30 with respect to the control was 61, 68, 63, 50, 19, 30, 56 and 27 for height, stem diameter, root length, number of leaves, fresh weight of root, dry weight of root, fresh weight of aerial part and dry weight of aerial part, respectively.

Microparticles from Wheat-Gluten Proteins Soluble in Ethanol by Nanoprecipitation: Preparation, Characterization, and Their Study as a Prolonged-Release Fertilizer

At present, the development of natural polymeric microparticles is carried out to obtain release systems. Prolonged-release systems are a potential solution to avoid nitrogen (N) losses in agricultural fields. The aim of this study was to develop microspheres from wheat-gluten proteins soluble in ethanol 70% (v/v), to ascertain their characterization, and to study their potential application in agricultural fields. Soluble-protein extraction was performed with 1600 mL of ethanol 70% (v/v). Likewise, ethanolic solutions with protein concentrations of 0.5%, 1%, and 2% (w/v) are classified as non-Newtonian fluids with pseudoplastic behavior. Using the nanoprecipitation method, it was possible to develop urea-loaded microspheres with a diameter ranging from 900 nm–1.7 μm. The Fourier transform infrared spectroscopy (FTIR) test exhibited interaction through hydrogen bonds between carbonyls and amino groups from the urea and proteins. Also, the thermogravimetric analysis (TGA) test demonstrated thermal stability at 130°C. The release experiment showed that the microspheres achieved equilibrium when 88% of the urea was released. Finally, according to the empirical model of Ritger and Peppas, urea release is carried out through Fickian diffusion. We conclude that the microspheres could be applied in the fields and with this improve agricultural practices. Also, they could reduce the potential environmental pollution and developing a sustainable agriculture.

Long-term biological effectiveness of Pochonia chlamydosporia var. catenulata against Meloidogyne incognita infection in a crop rotation systemi

ABSTRACT The aim of this study was to determine the effectiveness of Pochonia chlamydosporia var. catenulata and the bacteria Tsukamurella paurometabola strain C-924 (HeberNem™), to control Meloidogyne incognita infection in a crop rotation system (cucumber, tomato and pepper) under greenhouse production during six crop cycles. We determined gall index, prevalence, intensity of disease, and number of juvenile nematodes in soil. At the end of the sixth cycle, plants protected with P. chlamydosporia showed a reduction in gall index (≤2), prevalence, and median (42%) intensity of disease similar or more pronounced than those observed in plants protected with T. paurometabola (80%). Both treatments were more efficient at reducing galling than at reducing prevalence and therefore reduction of intensity of disease was mainly due to the reduction in galling. The hydrolytic activity of P. chlamydosporia and its resistant spores make this fungus one of the best options for the long-term control of RKNs by decreasing egg masses or galls. Pochonia chlamydosporia var. catenulata is an important part of a potential biological control strategy in rotation systems of vegetable crop and can be used for long-time IPM strategies in Cuba and the Caribbean.