Floristic diversity and vegetation analysis of Brassica nigra (L.) Koch communities (original) (raw)
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Auto-taxonomy of Brassica nigra (L.) Koch (Brassicaceae) in Egypt
Egyptian Journal of Botany, 2019
BRASSICA L. is one of the most economically important genera within family Brassicaceae, it includes approximately 80 species worldwide. In Egypt, the genus represented by five species. Among them, Brassica nigra (L.) Koch, which grown as a weed in field crops as well as roadsides of Mediterranean region. The field and herbarium observations reflected the notable morphological diversity within the species populations. Accordingly, morphological and palynological studies for the different geographical populations of Brassica nigra were carried out to trace the species diversity and helps for identification the infra-species taxa. The taxonomic revision of the species in Egypt, was carried out on the herbarium specimens as well as fresh materials represented by 26 populations, distributed along the Nile Valley and the Nile Delta. The results revealed the presence of two varieties namely var. bracteolata and var. nigra. The fruit peak and trichomes are the differential characters delimiting the two varieties.Moreover, the results showed also presence of var. nigra in two different biotypes. SEM of the seed coat and pollen grains showed the presence of notable infra-specific diversity. For pollen grains, the size, apertures and exine ornamentation confirming this diversity. Photographs and taxonomic key for varieties and forms will be addressed.
Weed flora in the reclaimed lands along the northern sector of the Nile Valley in Egypt
Turk J Bot (2013) 37: 464-488, 2013
Deserts comprise about 95% of the total land surface of Egypt; therefore, their potential for production must be assessed. Weed communities are mainly affected by the environment, and studies may increase our knowledge of the relationship among the weed flora, soil properties, crop rotation, soil management, fertiliser usage, and weed control. The area under study is one of the most recently reclaimed lands. The recorded 150 species in the monitored 19 sites were distributed within 33 families. The species-rich families were: Poaceae (31), Asteraceae (23), Brassicaceae (13), Chenopodiaceae (12), and Fabaceae (12). Chorological analysis revealed that the widely distributed species belonging to cosmopolitan, palaeotropical, and pantropical chorotypes constituted about 39.3% of the recorded flora. Pure Mediterranean species were very poorly represented, while biregional and triregional Mediterranean chorotypes constituted 28%. Saharo-Arabian chorotypes, either pure or penetrated into other regions, constituted 32%. Ubiquitous species with wide amplitude were Cynodon dactylon (L.) Pers. and Sonchus oleraceus L. Species richness varied from one crop to another. The winter weeds represented the main bulk of the recorded species within each crop, desert perennials exhibited notable variations, and margin species were the lowest. Redundancy analysis demonstrated the effect of soil organic matter, coarse sand, fine sand, silt, and soil saturation point on the spatial distribution of weed communities. The species–environment correlations were higher for the 4 axes, explaining 64.1% of the cumulative variance. The variations in soil pH, bicarbonates, ammonia, silt, and sulphate contents classified the vegetation into 4 site (vegetation) groups. Application of cluster analysis of species in crop–orchard farmlands resulted in 4 floristic groups (A–D). The weed species of the 2 winter crops, Egyptian clover and wheat, separated in Group A, tomato (winter/summer crop) in Group B, maize as a summer crop in Group C, and weeds of olive orchards and vineyards in Group D. This demonstrated high significant correlations between the olive and vineyard orchards (P < 0.01), and between the 2 winter crops, wheat and clover.
Eco-taxonomic study of family Brassicaceae of District Mardan, Khyber Pukhtoon- Khwa, Pakistan
2013
A total of 27 plant species belonging to 19 genera of the family Brassicaceae were collected from different localities of District Mardan. In which f ive plant species were belonging to genus Brassica , 3 species to Lepidium . Malcolmia and Raphanus had 2 species each, while Alyssum, Arabis, Capsella, Cardamine, Cardaria, Coronopus, Descurain ia, Eruca, Farsetia, Goldbachia, Nasturtium, Neslia, Notoceras, Rorippa and Sisymbrium had one species each. The wild species were Alyssum desertorum, Arabis taraxacifolia, Capsella bursa-pastoris, Cardamine hirsuta, Cardaria draba, Coronopus didymus, Descurainia soph ia, Farsetia jacquemontii, Goldbachia laevigata, Lepidium apetalum, Lepidium sativum, Malcolmia cabulica , Neslia apiculata, Notoceros bicorne, Rorippa indica, and Sisymbrium irio . There were 13.7% xerophytes, 82.7% mesophytes and 3.4%. Hydrophytes. According to Abundance scale, 41% were frequent, 17% occasional, 14% abundant, 7% very rare, 4% and 3% were dominant and rare specie...
Abstract Forty species related to 21 families were identified as the weeds of wheat from village Lahor, District Swabi during April 2005. Poaceae (7 spp), followed by Brassicaceae (5 spp), Caryophyllaceae, Asteraceae and Fabaceae (each with 4 spp) were the important families. The remaining families had single species. The most frequent species with more than 45% average frequency were Anagallis arvensis L., Arenaria serphyllifolia L., Chenpodium album L., Fumaria indica (Hausskn) H. N. Pugsley., Melilotus indica (L.) All., Rumex dentatus (Meissn) Rich., and Veronica biloba Linn. Based on importance value four communities viz., Arenaria -Anagallis-Chenopodium, Fumaria-Rumex-Chenopodium, Fumaria-Chenopodium- Anagallis, Arenaria-Fumaria-Chenopodium were deciphered. Caryophyllaceae, Fumariaceae, Chenopodiaceae, Fabaceae, Poaceae and Primulaceae were the dominant families on the basis of family importance values. The biological spectrum showed that there were 82.5% therophytes and 12.5% hemicryptophytes. Geophytes and chamaephytes were represented by one species each. Leaf spectra consisted of 42.5% microphylls, 35% nanophylls and 22.5% leptophylls. Biomass of the forbs was higher than the grasses. Species diversity was higher in Koz Mulk and Pani owing to crop rotation.
Diversity and Biostatistics of the plant life in the Northwest of the Delta, Egypt
The paper investigates the diversity and the floristic structure of plant life in the Northwest of the Delta, Egypt. Using Biostatistical techniques the author tracked the impact of some environmental factors on the spatial distribution of weeds among 14 sites and their performance within the assemblages associated with a total of 25 crops monitored in the surveyed area. A total of 473 specific and infraspecific taxa were recorded belonging to, 58 families and 268 genera; and the rich-species families were: Poaceae, Asteraceae, Amaranthaceae, Fabaceae, Brassicaceae, Caryophyllaceae and Cyperaceae, respectively. The Botanical Nomenclature of the recorded species were updated according to the Plant List created by the Collaboration between the Royal Botanic Gardens, Kew, and Missouri Botanical Garden (Version 1.1 (September 2013) to compare the performance of species and similar in the subsequent studies. The records of weeds declared that winter weeds constitute the bulk of the recorded species (≈ 63%) and the chorological analyses revealed that they fall under 19 chorotypes and the winter weeds are mainly Mediterranean either pure (53 species) or with extensions into other territories (170 species); while the summer weeds are mainly palaeotropical (43 species) and most of the all-the-year-round weeds are either cosmopolitans or paleotropical. The presence was taken to indicate the degree of ecological success and sociological performance of the species. The degree of seasonal bias was calculated as to increase the knowledge about the seasonal performance of weeds and relate to weed control; and the results had declared that: 39 species of the winter weeds and 23 species of the summer-weeds showed tangible growth in the corresponding other half of the year. Sites and their localities were classified according to the 12-major soil textural classes defined by the USDA soil taxonomy. Biostatistical techniques included Clustering, Multivariate analyses and ordination. Principal Components Analysis (PCA) summarizes the effect of some ecological factors that influence the variation in the vegetation of the 14 sites monitored. The first two axes explained 75.42% of the total inertia; and the samples (sites) where the sandy soil dominates were separated along the positive end of PC1; while those where clay and loamy soils dominate were separated along its negative end. The map of the correlation circle showed that the projection of the following initial variables in the factor space was positively linked with PC1: Species richness (S), Mediterranean element, Shannon_H, Rate of weed seasonality, Rate of crop sustainability and Paleotropical chorotype. Four clusters or vegetative sociation groups (AD) were resulted from Agglomerative Hierarchical Clustering (AHC) and the chorological analysis showed that Group D earned the highest score of the Mediterranean species. The Alpha (α) diversity and Beta (β) diversity indices were measured for the four weed communities. The results of α-diversity indices declared that Group C scored the highest Equitability and Dominance and the lowest Species richness and Shannon-Wiener diversity index values; while Group D was on the contrary; and the other groups gained values between them and the results of the pairwise comparisons for the floristic structure of the weed communities were located in a table indicating the β-diversity index, and by the use of DCA; the magnitude of change in species composition among the sites and the total beta diversity have been measured among the gradient. One-way ANOVA followed by Tukey's test (HSD) showed that out of the 15 soil variables, 9 variables were of significant variations and Canonical Correspondence Analysis (CCA) results showed that most of the inertia is carried by the first axis (Eigenvalue = 0.028 and percentage of inertia (CCA1) = 91.23%); and with the second axis we obtain 98.94%. The CCA axis 1 was positively correlated to the Coarse sand, Fine sand, Mg, K, Cl, Ca, Na, T.S.S. and H.C. with which the frequency was associated for Group D; and it was negatively correlated with Clay and silt with which the frequencies were associated for Group A and B. The CCA axis 2 was strongly correlated with CaCO3; and Group C was the most sensitive for the variable and with which the frequency of species had been associated. Pearson's correlation coefficient (r) showed very high strength of linear relationships between paired data: for most of winter crops; for about half of the summer crops and for the two perennial crops. Most of the orchards paired data showed strong correlations and a variable performance with the other agroecosystems and some of them declared strong correlations with weed assemblages associated with some of the winter crops or summer crops. Using NMDS algorithm four floristic sociation groups (A – D) were identified. The results were represented by NMDS data map (2-D-plot) and winter crops (Group A) were ordinated to the positive end of Dim1, summer crops (Group B) to the negative end and perennial crops and orchards (Groups: C & D) in an intermediate position; while crops were separated according to their soil moisture requirements among Dim2.
Auto-taxonomy of Brassica tournefortii Gouan. (Brassicaceae) in Egypt
Bangladesh Journal of Plant Taxonomy
Brassica tournefortii Gouan. (family Brassicaceae) is one of the five species in the Egyptian flora. Its populations showed notable morpho-plasticity with taxonomic debates, which were not yet resolved. The current study was carried out to assess the species morpho-plasticity and its molecular identity based on ISSR. The study was applied to 27 herbarium and fresh populations, representing all the species distribution ranges in Egypt. The taxonomic revision included 70 morphological characters, revealed five distinct Forms (1-5), radical leaf, and fruit provided the major distinguishable traits among the studied 70 morphological characters based on them the morphologic key is provided to delimit these forms. The pollen grain features using SEM are a pioneer at the infra-specific level, two shapes observed the subprolate (Forms 1& 3) and prolate (Forms 2, 4 & 5). Furthermore, the exine micro-features possess taxonomic value at the infraspecific level. The cluster analysis based on IS...
Floristic Biodiversity of Weed Communities in Relation to Conventional and Organic Farming
This experiment was conducted at the Superior Institute of Agronomy at Chott-Meriem (Sousse, Tunisia). Weed abundance, species richness and diversity in conventional and organic irrigated vegetable crops in Chott-Meriem were compared in spring by means of a relative abundance index for each species. Shannon's index was used to assess the effect of intensification on the floristic composition and structure of weed vegetation, while a community coefficient was used to evaluate the degree of resemblance between the two floras and to evaluate the role of organic farming in preventing the continued loss of biodiversity caused by intensive farming practices. 8 paired crops were selected and the samples were arranged in randomized complete design. Each pair contained one long-term established organic (for at least 20 years) site and one conventional site. 160 samples were collected from primary plots and analyzed separately or together. 64 samples of 100 g soil were used for analysis of organic matter, nitrogen, pH and electrical conductivity. The weed species were identified and classified according to their importance and type of distribution. Results showed that abundance, species richness and diversity were higher in organic than in conventional fields. This study also showed that the conversion from conventional to organic farming inverted the weed flora. The organic matter content and the salinity were higher in organic soils. The abundant biomass present in organic farming may promote biodiversity and help to biologically control pests and favor insect pollination. A better understanding of changes occurring in the composition of the weed flora could result in a better weed control strategy.