The impact of five environmental factors on species distribution and weed community structure in the coastal farmland and adjacent territories in the northwest delta region, Egypt

Annual and geographical variations in the specific composition of jassids and their damage on cotton in Ivory Coast

In recent years, jassids have become a real problem for cotton growing in Ivory Coast. It is important to investigate the causes of this problem. The aim of this study was to highlight the diversity of jassid species and their impact on cotton growing in Ivory Coast. The collections carried out in 2021 identified three species. Jacobiasca lybica (Bergevin & Zanon, 1922) is the most abundant, with proportions ranging from 73.3 to 93.3% depending on the site. The other two species are Empoasca papayae (Oman, 1937) (8.3%) and Empoasca facialis (Jacobi, 1912) (5%). In 2022, collections revealed the invasion of a new species, Amrasca biguttula (Shiraki, 1913), which became dominant with proportions of 90 to 100% depending on the site. Two other species, Jacobiasca lybica (Bergevin & Zanon, 1922) (2.7%) and Empoasca facialis (Jacobi, 1912) (1.3%), cohabit with Amrasca biguttula (Shiraki, 1913). Thus, while the damage noted in 2021 was attributable to Jacobiasca lybica (Bergevin & Zanon, 1922), that observed in 2022 is essentially due to Amrasca biguttula (Shiraki, 1913), with incidences exceeding the economic impact threshold. The North-East of the cotton basin was the area most affected by attacks by these two species. The results of the study reveal significant changes in jassid species composition and climatic conditions in the cotton-growing areas of Ivory Coast, from 1 year to the next. This situation also explains the variations in damage levels.

Measuring the ecological preference for growth of 150 of the most influential weeds in weed community structure associated with agronomic and horticultural crops

The phytosociological researches which intent for studying the performance of weeds and the structure of weed assemblages associated with different crops derives their importance mainly from the adverse effect of weeds on crop productivity. Consequently, it is worth questioning about the ecological preferences of the weed growth in response to three main drivers for weed community structure associated with agronomic, and horticultural crops: crop diversification, crop seasonality, and soil type. A study area was selected comprising farmland of Nile Delta and its adjoining east and west territories, Egypt. A total of 555 species were recorded in 30 agroecosystems monitored and depending on species frequency/abundance values, 150 species were designated as the most influential weeds in weed community structure associated with agronomic and horticultural crops. The ecological preference of species for crop seasonality was evident through the results of Agglomerative hierarchical clustering. Three weed assemblage groups (WAG) identified: WAG A associated with winter agronomic crops, WAG B associated with summer agronomic crops, and WAG C associated with perennial agronomic crops and horticultural crops (orchards). Their diversity evaluated at different levels. The growth preference of the 150 species which were assigned as most influential weeds was gauged in response to the three environmental variables. 61 species were faithful to WAG A, 45 to WAG B, and 44 to WAG C. Concerning crop diversification, 34-species were significantly affected and scored coefficient of variation ≥ 100%. As for soil type, indicator species analysis revealed that 66-species show growth preference in fine grained soil while 84-species prefer coarse grained soil. In the three vegetation units (WAG A - C), 12 within-group associations (alliances) were specified of less-common (differential) species. The record of these alliances match to a specific environmental condition (ecological niche) and in them 29 strong indicators are identified. Redundancy analysis was used to extract and summarize the variation in species records in the response matrix (species vs. sites) that can be explained by the three different types of growth preference (explanatory variables), and the partial linear effect of them was evaluated by variation partitioning.

Cereal weeds variation in middle Egypt: Role of crop family in weed composition

Cereals occupies a major part in the diet of humans globally, participating more to our daily protein and calorie intake than any other crop. The present study highlight the weed flora of cereal crops compared to other crops in middle Egypt and their distribution. Ninety-two weed species were recorded in the all studied crops, cereal and other crops; in the studied area belong to 67 genera and 20 families. Egyptian clover; showed the highest numbers of both weed species and genera followed by wheat, on contrast the lowest weed species and genera numbers were recorded associated with Solanaceous crops tomato and pepper. Wheat crops exhibited the highest number of weed species, among cereals, followed by maize crop, while the lowest weed species number was detected in barley crop. Chenopodium murale, Cynodon dactylon, Convolvulus arvensis and Malva parviflora were the most frequent species in winter cereals, while Echinochloa colona, P. oleraceae were the most frequent weeds in summer cereals. Chorological analysis of the recorded weed species showed that cosmopolitan elements showed the highest numbers in total weed flora Differences in weed species compositions were fundamentally influenced by seasonal priority. Based on TWINSPAN and Ward classifications, crop family showed slightly effect as a factor affecting weed composition.

Comparative view for the impact of five eco factors on species distribution and weed community structure in Isthmus of Suez and adjoining farmland east Nile delta, Egypt

The study of the extent of variability and the order of importance for the impact of environmental factors on species distribution and weed community structure from one region to the other is an interesting research subject. The present study aimed to discuss the issue to give a comparative view with the author's findings about the impact of the prevailing climate, soil type, crop type, crop sustainability and urbanization on species distribution and weed community structure in the coastal farmland and adjacent territories in northwest delta region (Mahgoub, 2019). A new sample area selected and comprised the reclaimed land of El Ballah region in Isthmus of Suez and adjoining farmland east Nile delta. A total of 245 species were recorded. Agglomerative Hierarchical Clustering (AHC) identified four vegetative sociation groups (VSG). The diversity of the four identified VSG or weed communities was evaluated at different levels. Parincipal Component Analysis (PCA) indicated the influence of the five eco factors on species distribution and variability of weed community structure, summarized the relationships among variables and investigated the proximity among samples and how they related to variables. ANOVA followed by Tukey's test were applied twice for the resulted VSG, one depending on soil variables as explanatory variables and the other on sampling site's indicative scores for the five eco factors. The results of ANOVA (R², F, P), sample variance (S²) and other multivariate analyses indicated a different order of importance for the impact of the five eco factors in comparable to the former study denoted above. The soil type was the most impacting factor on species distribution and weed community structure, followed by crop type, crop sustainability, prevailing climate and urbanization, respectively.