Composición nutricional de tres pastos colectados en el estado de Morelos, México

El objetivo de este estudio fue evaluar tres pastos forrajeros, Bromus diandrus, Oplismenus burmannii y Heteropogon contortus, de las subfamilias Pooideae, Pooideae y Panicoideae, respectivamente. Las principales variables respuesta, todas en base seca fueron: cenizas (Cen), proteína cruda (PC), extracto etéreo (EE), carbohidratos solubles (CS), fibra detergente neutro (FDN), contenido celular (CC = 100 - FDN) y digestibilidad in vitro de la materia seca (DIVMS). Cada pasto se evaluó por triplicado y una repetición se consideró la unidad experimental. Las medias fueron separadas mediante la prueba de Tukey (p < 0.05). La asociación entre cada par de variables (p < 0.05) se estimó usando el coeficiente de correlación de Pearson (p < 0.05). Los pastos B. diandrus y O. burmannii resultaron con más PC, CC y DIVMS y con menos pared celular o FDN (componente insoluble) que H. contortus. Esto produjo una correlación positiva entre CC y PC (0.751, p < 0.05). Adicionalmente, O. burmannii produjo el valor más alto de Cen y el más bajo de CS, mientras que B. diandrus mostró el valor más bajo de Cen y el más alto de CS. Esto produjo una correlación negativa entre estas dos variables (-0.976, p < 0.01). En conclusión, B. diandrus, mostró mejor composición química y digestibilidad, que los otros dos, por lo que se recomienda este pasto para la nutrición de rumiantes.

Genetic diversity and population structure of Heteropogon contortus L. germplasm collected from diverse agro-climatic regions in India and development of a core germplasm set

Heteropogon contortus, an important constituent of major grasslands of India, Australia and many countries in Africa, Asia and the Americas, is important for pasture and grassland productivity. Hence genetic improvement of the grass needs attention. A genetic variability study, including development of a core subset, was carried out by evaluating 235 accessions collected from different agro-ecological zones of India. The study, based on 16 metric and 14 non-metric traits along with 8 nutritional parameters, indicated that considerable genetic variability existed among the germplasm and selection could result in identification of suitable types for target environments. Clustering and subclustering was performed to select 35 accessions to form a core subset. The statistical analysis indicated that the core subset captured almost all the variability present in the entire germplasm. The study will help researchers to focus future studies on this core subset in developing genetic improvement programs.

Responses of bacterial communities to spatial distribution and biogeochemical migration in Panzhihua mining tailing

&lt;p&gt;Heteropogon contortus were the domiant plants in Panzhihua mining tailing due to the characteristic of drought-enduring and toxicity resistance. The aim of this work was to determine the effects of the successive planting of Heteropogon contortus on soil characteristics, including heavy metals contents and biogeochemical migration. Spatial distribution of heavy metal and enzyme activity in surface soils and rhizosphere soil as well as responses of bacterial community were systematically researched. In the meanwhile, High-throughput 16s RNA sequencing results indicated that the abundance and diversity of bacterial communities from different altitude locations were quite diverse in soil samples. The contents of some heavy metals and enzyme activity markedly affected on the structures of bacterial communities surface soils and rhizosphere soil. The most abundant bacterial communities were Actinobacteria (29.74 %), Proteobacteria (28.06 %), Chloroflexi (13.73%) in phylum level in the original soil samples. The abundance of Proteobacteria (19.87 %, 27.57 %, 29.35 %) and Patescibacteria (1.56 %, 1.83 %, 2.66 %) of non-rhizosphere soil was gradually increased along with the increasing latitude, which is just the opposite rule to the abundance of Acidobacteria (17.19 %, 14.58 %, 11.77 %) and Gemmatimonadetes (4.61 %, 3.17 %, 2.86 %). Results in this study emphasized the heavy metal contaminations in soils and rhizosphere soil, providing valuable information on how heavy metal contamination influences soil bacterial communities across a chronosequence spanning 50 years.&lt;/p&gt;

Restricted Effect of Two Plant Root Systems on the Crack Expansion of China Yunnan Laterite under Dry-wet Cycle

In order to research the restricted effect of hedera nepalensis root systems and heteropogon contortus root systems on the crack expansion of Yunnan laterite under dry-wet cycle, this paper prepares Yunnan laterite with certain moisture content, and makes the compacted samples of pure laterite and composite soil mixed with root systems by adopting hedera nepalensis root systems and heteropogon contortus root systems respectively, and then simulates the dry-wet cycle of laterite in engineering (i.e., rainfalls and evaporations), measures the crack width of samples experiencing different cycles, and makes statistical analysis on the average maximum crack width of samples in all groups by adopting the method of indoor spraying and natural drying. The result indicates that, 10% and 20% mixed hedera nepalensis root systems can exert obvious restrictions on the crack expansion of Yunnan laterite after dry-wet cycle, while 30% mixed hedera nepalensis root systems and 10% mixed heteropogon contortus root systems can also restrict the crack expansion of Yunnan laterite, but the restricted effect is weaker. As for 20% and 30% mixed heteropogon contortus root systems, composite soil samples will disintegrate after the 2nd dry-wet cycle.

Heteropogon contortus (spear grass).

H. contortus is native to Africa, temperate and tropical Asia, Australasia and southwestern Europe, and is naturalized in southern USA, Mexico, the Caribbean, Central and South America (USDA-ARS, 2017). It is reported as naturalized in Hawaii by USDA-ARS (2017) but according to University of Hawaii (2009), it is not clear whether H. contortus is indigenous to Hawaii or a Polynesian introduction. USDA-ARS (2017) and Baldwin et al. (2012) report H. contortus as an alien species in California, USA, but according to Calflora (2017), it is native in California.

Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River

The soil water was stratified sampling and analyzed with 0–100 cm by three plantation (Leucaena Benth Forest land, Dodonaea angustifolia Shrub land and Heteropogon contortus grassland) at the dry-hot Valley in Jinsha River, at June, September, December of 2016, which were to know about the variation and mechanism of soil water movement. The results showed that (1) soil water in different soil layers is significantly different, and the overall performance is shrub land (11.65%) > grassland (8.29%) > forest land (6.76%); (2) the δD isotope ratio of the soil water from all samples ranged from −146.359% to −54.628% and the δ18O isotope ratio ranged from −20.272% to −2.148%, and there is a good linear relationship between isotope ratios of soil water of three different soils; (3) there is a change with season: the intercept of the isotopes ratio at different months decreased in turn, June < September < December. While the shrub lands and grassland had the same pattern but slightly different, the isotope ratio of soil moisture in December was lower, and the intercepts of shrub land in September were significantly larger than in December; (4) there is a change in space: the total difference isotopes ratio of soil water is larger at the shallow soil layer and changed sharply at all positions of the forestland, while those in the shrub land and grassland changed became relatively weakly. This study provides the theoretical basis for the key problems of plant water using mechanism, ecological water demand, vegetation recovery and so on.