The main objective of this research was to quantify tannins at the bark and wood level in lethersteam species (Jatropha dioica). Plant samplings were carried out during the 1995 winter in the Mapimí, Durango sierra for chemical analysis, the Vainillina/HCI method (Bums, 1971), modififications by Prisa et M. (1978) were used. Results were analyzed by a statistical linear model, finding that tannin mean concentration was 99.09g. equivalent of catequina/Kg. of dry matter. No significant difference was found with respect to weight, and therefore no direct relationship with age was established. Final results showed an overwhelming difference (P< .05). In condensed tannin, concentrations between root and stem being higher in roots, and also significant differences (P< .05) between the bark and the wood, being higher in the bark; this was independent of the age for both. Scarce research in the utilization of vegetable tanning agents, and partícularly of useful plants for the tanning industry, represent a wide field of study.

The pickly pear (Opuntia spp) is a natural resource of high potential profits in the arid lands, however little biochemical research has been done. In this study apexes of primary (El) and secondary (E2) adventitious roots of cladodes of a year of two cultivate of Opuntia megacantha Salm-Dyck: VIII resistant (CT) and 35 susceptible (CS) to the drought were used; They were put under temperatures of 25 (T1), 37 (T2) and 47°C (T3) in a camera with air circulation for three hours, to determine the effect and its possible use like marker of the tolerance to the heat. A factorial design of treatments and an experimental design totally at random was used. The statistical analysis did not show significant difference between temperatures nor between varieties. Age was highly significant (P=0.00011) begin higher in El (1.5037 mg g-1 dry weight) than in E2 (0.5418 mg g-1 dry weight). Temperature control of soil and salinity of water for concentration use of proline is suggested as a tolerance to heat selection index.

The objective of this research was to estimate the essential oil content in wild marjoram (Lippia graveolens H.B.K.). Leaf samples were taken from plants at different locations in Mapimí, durango on thirteen different dates. The leaves were separated in three categories, according to their height, the humidity and total ashes. The essential oils, refraction indexes, and specific gravity of these samples were determined by vaporization. The relative abundance of tymol and carvacrol were also obtained, using a gas chromatographer connected to a mass spectrometer (GC/MS). The averange yield of the oils was 5%. The oil extraction process showed acceptable levels of tymol (31%) and crvacrol (7%) however, the plant height levels were influenced by several factors including the leaf oil content, the plant maturity, and their location of growth.

Mezquite is a characteristic tree of arid and semi-arid lands. It grows where there are reduced numbers of wooded species and is a very exploited resource. Only through adequate research and preservation can such uses for the explotation be defined. Chemical analysis of mesquite pods (Prosopis glandulosa var. torreyana) in 6 stages of fruit development were analysed on pruned and non-pruned trees. Fat, ashes, humidity, crude fiber, protein and carbohydrates were all defined in a completely random study, designed with two factors; date and type of tree. Carbohydrate differences in the trees initially varied among the trees however, there was no difference in dates and humidity. After ten days, differences in protein were clear, while after forty days, differences in the crude fiber and carbohydrates were found. Studies later would show that, after fifty days, the ashes and fat varied between the trees. Results of this study showed that: the pruned trees had more nutrients. This has also has a direct relationship with the trees maturity. Between ten and twenty days one could get pods for protein. Crude fiber varied from forty to fifty days and for fats and carbohidrates fifty days or more were sufficient.

Noa (Agave victoriae-reginae T. Morre) is a botancial species. Currently, there is a major threat to it’s existance. A study was conducted to test the effect, that seeds stored for three years, would have, not only on the percentage of germination, but the speed at which the plants would germinate. The species were harvested in four time frames; (D). D1 (March to April of 1993); D2 (May to June of 1993); D3 (September to November of 1992) and D4 (December of 1992 to February of 1993). This included six pregerminative treatments which were closely monitored: saturating the seeds in distilled water (20 hours), stratification of the seeds at 4 to 7°C (48 hours), saturating the seeds in thouris 0.5% (3 hours), saturating the seeds in Ag3 100ppm (6 hours), and saturating the seeds in potassium nitrate 2% (half hour). Twenty seeds were disinfected with chlorine and placed in petie dishes, given four treatments, and then incubated between 27-30°C. No effect between treatments was found. Upon the examination of the saturation in distilled water and stratification processes, both were found to have equal results. Even when tested at 92.5%, 96.25%, and 95% germination respectively. However, the best information frame from collecting the D4 data, where all the treatments were the same stastically. They showed a much higher percentage at 86.25% to 97.5% germination. The germination percentages did not disminish with the storage times but rather, they were found to be preserved. The time frames of D1, D2, D3 found lower germination percentages than that of D4. The speed of germination was lower when compared to previous studies. These studies showed a 95% germination rate in a 7 day period, whereas, this study achieved these same results in a 34 day period.

The ecological diagnostics of vegetational studies had many great discrepancies amongst scientists, thus the reason for why the present studies were located at 24°52'30" - 25°02'30" north latitude and 103°37'30" - 103°47" west longitude. Techniques with different vegetational communities were used and shown on a map at 1 :50,000 scale. With parameters obtained on the field, charts were made giving the important value to be set for each of type of vegetation. These geological, edaphic and topographical charts were then used tor the corresponding ecological factors. Six vegetational types were identified and shown bye their range coefficient (obtained by the Range Coefficierit Technical Comission, 1979) totalling 25,435 hectares. Included in the summary as well, was the eroded surface or area devoyed of vegetation. Having this diagnosis determines the direction for the best use, management and conservation of the available resources in the studied area.

The tissue Culture Lab (Regional Branch for the Study of Arid Lands) at the University of Chapingo evaluated the effect of using formaldehide, benzoic acid and lugol as an inhibitor on the growth of pollution agents in a vitro culture of date palm (Phoenix dactylifera L.) seeds. The effect of these sustances on seed germination and root growth were also evaluated. In the statistical analysis in fungi pollution, bacteria pollution and seed germination, the Fisher’s Exact Test was used with α=0.05 as the significant level. The Kruskall & Whalis test was used for more than two independent test in the root growth with the procedure for bing n. Results indicated that all the antibiotics had no inhibitory effect on the bacteria, fungi pollution or germination. Root growth was strongly inhibited by benzoic acid. Formaldehide and lugol showed equal statistical behavior three weeks after in vitro seeding.

Soil management influence on water relationship (water potential, osmotic potential, turgent potential) for nine kinds of beans (Phaseolus vulgaris L.) were evaluated in order to select genotype w/ith a high tolerance to water short high tolerance to water shortages genotypes. Also evaluated were soil management practices that give as a result the best yield. The best results in water relationships were obteined with furrow and bed seed. Both specificly for osmotic potential and turgent potential, as well as subsoil and not subsoil for the water potential (Ψ). Three of the nine varieties evaluated had possible evidences of drought resistance: Negro San Luis, Pinto Lagunero-87, Bayo Coba, which is important because it is possible to carry out genetic improvement to get higher drought tolerance varieties.

An in depth inspection was carried out to present a thorough overview on the effects of toxic plants located in the arid and semi-arid lands of northern Mexico. The active toxin principaly, was found to have entered an organism oraly and was then further absorbed through the organism’s digestive tract. The toxin was found to affect the organism by distributing itself and modifying the enzimatic process. This would later affect the organism psychologicaly. Great economic losses to the cattle industry are in part by toxins whose main source of entry is oral, further affecting the organism’s health, productivity and reproduction rates. Main substances identified in toxic plant were: alkaloids, nitrates, hydrocyanic acid, oxalates, saponins, and selenium. Their general characteristics, mechanisms of action, lesions, clinical signs and treatments were reviewed. Finally, a list of 59 toxic plants in the studied area were compiled and presented in this work.