Plants In Agricultural Systems Research Articles

Correction: Mena, G.T.; Gospodarek, J. White Mustard, Sweet Alyssum, and Coriander as Insectary Plants in Agricultural Systems: Impacts on Ecosystem Services and Yield of Crops. Agriculture 2024, 14, 550

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White Mustard, Sweet Alyssum, and Coriander as Insectary Plants in Agricultural Systems: Impacts on Ecosystem Services and Yield of Crops

The main reason for adding plants to accompany the main crop is to protect it from pests and diseases. We reviewed the effectiveness of white mustard (Sinapis alba L.), sweet alyssum (Lobularia maritima L.), and coriander (Coriandrum sativum L.) in this regard. White mustard proximity had a strong positive influence on the occurrence of Syrphidae, parasitoids, Coccinellidae, and Carabidae, as well as on the fertility of Syrphidae and the longevity of parasitoids—all of which are essential for biological pest control. It also reduced many pests and diseases. The influence of S. alba on yield depends on the spacing used and the species of protected plant. Sweet alyssum positively affected the occurrence of Syrphidae, Coccinellidae, Anthocoridae, epigeal, and soil fauna, as well as the longevity of parasitoids and Anthocoridae. Its effect on the crop yield is variable, depending on the references consulted. The sensitivity of L. maritima to Phyllotreta spp. excludes it as a companion plant for hosts of these pests. Coriander positively affected the occurrence of Chrysopidae, Coccinellidae, Staphylinidae, and Aranea, as well as the longevity of parasitoids and the egg-laying of Syrphidae. It also reduced some crop pests. Introduction of the reviewed plants can improve the biodiversity of beneficial entomofauna that can help control pests and reduce diseases, with benefits to crop and yield. The use of synthetic insecticides can thus be greatly reduced, though it is not always possible to avoid them completely.

Flowering margins support natural enemies between cropping seasons

IntroductionPopulations of natural enemies of insect pests are declining owing to agricultural intensification and indiscriminate use of pesticides, and this may be exacerbated in agricultural systems that clear all margin plants after the cropping season for other uses such as fodder. Retaining a diversity of non-crop flowering vegetation outside the cropping season may support more resilient and effective natural pest regulation.MethodsWe tested the potential for non-crop vegetation to support natural enemies in fields across two locations after harvesting the primary crops of lablab and maize.ResultsA total of 54 plant species were recorded across the sites in Kenya with 59% of them being annuals and 41% perennials. There was a significant seasonal variation in plant species richness (ANOVA: F1, 16 = 33. 45; P< 0.0001) and diversity (ANOVA: F1, 16 = 7.20; P = 0.0511). While time since harvesting was a significant factor influencing the overall abundance of natural enemies (ANOVA: F2, 1,133 = 8.11; P< 0.0001), they were generally higher in abundance in locations with margin plants or where a diversity of margin plants was observed.DiscussionThese findings demonstrate that flowering plants in agricultural systems offer refuge and alternative food for natural enemies and potentially other beneficial insects between cropping seasons. The conservation of natural enemies between crops may lead to more effective natural pest regulation early in the following crop, thus reducing reliance on insecticides application.

Comparison of bacterial diversity, root exudates and soil enzymatic activities in the rhizosphere of AVP1-transgenic and nontransgenic wheat (Triticum aestivum L.).

Soil microbial communities are among the most diverse communities that might be affected due to transgenic crops. Therefore, risk assessment studies on transgenes are essentially required as any adverse effects may depend not only on the specific gene and crop involved but also on soil conditions. The present study deals with the comparison of bacterial populations, root exudates and activities of soil enzymes in nontransgenic and AVP1-transgenic wheat rhizosphere, overexpressing vacuolar H + pyrophosphatase for salinity and drought stress tolerance. Amounts of organic acids and sugars produced as root exudates and activities of dehydrogenase, phosphatase and protease enzymes in soil solution showed no significant differences in AVP1-transgenic and nontransgenic wheat rhizosphere, except for urease and phenol oxidase activities. The higher copy number of nifH gene showed the abundance of nitrogen-fixing bacteria in the rhizosphere of AVP1-transgenic wheat compared with nontransgenic wheat. nifH gene sequence analysis indicated the common diazotrophic genera Azospirillum, Bradyrhizobium, Rhizobium and Pseudomonas in AVP1-transgenic and nontransgenic wheat except for Zoogloea detected only in nontransgenic wheat. Using 454-pyrosequencing of 16S rRNA gene from soil DNA, a total of 156, 282 sequences of 18 phyla were obtained, which represented bacterial (128,006), Archeal (7928) and unclassified (21,568) sequences. Proteobacteria, Crenarchaeota and Firmicutes were the most abundant phyla in the transgenic and nontransgenic wheat rhizosphere. Further comparison of different taxonomic units at the genus level showed similar distribution in transgenic and nontransgenic wheat rhizospheres. We conclude that the AVP1 gene in transgenic wheat has no apparent adverse effects on the soil environment and different bacterial communities. However, the bacterial community depends on several other factors, not only genetic composition of the host plants. The present research supports introduction and cultivation of transgenic plants in agricultural systems without any adverse effects on indigenous bacterial communities and soil ecosystems.

Nitrogen Fixation Using Symbiotic and Non-Symbiotic Microbes: A Review Article

Nitrogen (N) is one of the key drivers of global agricultural production and needs 150-200 million tons each year by plants in agricultural systems to produce the world’s food, animal feed and industrial products. Hence, to minimize this problem industrially producing nitrogen fertilizer is necessary. However, this industrially produced nitrogen fertilizer affect the world ecosystem through different mechanisms and effective exploitation and utilization of biologically fixed nitrogen in agricultural systems is necessary. This naturally fixed nitrogen minimizes the rate of cost of crop production, urea volatilization and is the sustainable soil fertility maintenance. Despite the importance of biological nitrogen fixation is sustainable and environmentally friend approach, some researches were done on legume crops through exploring variety specific rhizobia species for legume crops and shortage of information on free living nitrogen fixer of bacteria species for cereal crops which will be the future concerned research. This paper review discusses biological nitrogen fixation mechanism symbiotically and non-symbiotically either through free living bacteria or associative with host plant. It also focused on types of bacteria in which fix atmospheric nitrogen in cereal crops and factors affecting biological nitrogen fixation in lesser amount.

Phytotoxicity evaluation of six fast-growing tree species in South Africa

Vachellia sieberiana, Albizia adianthifolia, Buddleja saligna, Combretum kraussii, Halleria lucida and Rapanea melanophloeos are fast-growing, indigenous tree species in South Africa. They are usually found growing alongside other plants in agricultural systems. In this study, the comparative phytotoxic activity of aqueous leaf extracts of these tree species at different concentrations was investigated using lettuce seeds (Lactuca sativa L.) in a laboratory bioassay. To simulate natural situations, seeds were germinated under 16h light/8h darkness in a growth chamber using distilled water as control. The results showed that germination, chlorophyll accumulation and growth indices (plumule and radicle lengths) were significantly inhibited with increasing concentration of plant extracts. The treated lettuce seedlings experienced lipid peroxidation at high extract concentrations (1.0% and 2.0%) as evidenced by increased concentration of malondialdehyde (MDA). In response to this, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) increased at low extract concentration but significantly dropped as concentration increased. These results suggest that aqueous extracts of the studied tree species may produce growth inhibitory substances. Thus, our study revealed that these trees possess phytotoxic activity which could be exploited in the management of weeds in agroforestry systems.

Bigger may be better in soil N cycling: Does rapid acquisition of small l-peptides by soil microbes dominate fluxes of protein-derived N in soil?

In natural plant–soil systems and following incorporation into plants in agricultural systems, most nitrogen enters soil as protein or other biological polymers. Before this nitrogen can be taken up by soil microorganisms or plants, it must be cleaved to a form which can be transported into the organism. It is well known that soil microorganisms and many plants can utilise l-amino acids and a growing body of evidence shows that short l-peptides can be taken up without further modification. However, there has been very little empirical investigation of rates of uptake in soil. d-amino acids and their peptides are less abundant in soil than their l-enantiomeric counterparts, but do occur in significant quantities. To date their potential rate of cycling in the soil solution remains virtually unknown. We directly measured rates of uptake of 14C-labelled l- and d-alanine and their di- and tripeptides in a temperate agricultural soil. All were taken up extremely rapidly by soil microorganisms. Half-times for l-enantiomers and the d-amino acid monomer were all less than 1 min, with l-peptides accounting for the highest potential fluxes (9 nmol N g−1 DW soil min−1), more than double that of the amino acid monomer. Uptake of d-peptides was slowest with half-times in soil solution of 10 and 36 min (di- and tripeptide, respectively). Availability of l-peptides had a much stronger effect on the rate of uptake of the amino acid monomer than the amino acid monomer had on the uptake of the peptides, suggesting a microbial preference for peptides. We suggest that very high potential N fluxes and an apparent microbial preference for l-peptides indicates that most N is cycled through the soil solution as l-peptides early in protein degradation, and that this is the site of fiercest competition for soil N.

Prospects for three Dorycnium species as forage plants in agricultural systems: a review of their agronomic characteristics

Perennial legumes in the Dorycnium genus may have potential as forage plants that could reduce the seasonality of feed production and improve the sustainability of agricultural systems. However, Dorycnium species are not currently used commercially and little is known about their agronomic characteristics. This review covers the current knowledge on Dorycnium distribution, taxonomy and the agronomic performance of Dorycnium hirsutum, Dorycnium rectum and Dorycnium pentaphyllum, including adaptation, establishment, biomass production, water use, grazing management and nitrogen fixation, along with considerations for animal production. Dorycnium originate from temperate Europe and the Mediterranean basin and may be suitable for other regions with similar climatic conditions. Little data exist on the climatic and edaphic conditions to which Dorycnium species are best adapted. Current evidence suggests that D. hirsutum is widely adapted and might be suitable as a forage plant for acid soils in drier and frost-prone agricultural regions. D. hirsutum also persists well in low rainfall environments (down to 300 mm mean annual rainfall), can produce up to 21 t dry matter(DM)/ha in its first 3 years and, by utilising extra water compared with annual pastures, can reduce water leakage below the root zone, thereby slowing development of dryland salinity. The use of D. rectum would be limited to high rainfall or water-accumulating sites. D. pentaphyllum is a diverse species, yet available material appears to be less productive but has better forage quality than D. hirsutum. Currently, establishment reliability and/or forage digestibility are major limitations of the tested Dorycnium species that restrict their potential role and challenge the feasibility of their future use. Breeding may overcome or minimise these limitations and improved agronomic management might also enhance their usefulness. However, current collected genetic resources of Dorycnium are very limited and targeted collections would be needed to yield better adapted germplasm. Breeding to reduce the high levels of condensed tannins (>13% of DM) to moderate concentrations in Dorycnium might improve forage digestibility and could have positive implications for animal performance and health. Despite the poor digestibility of some Dorycnium species (<60% DM digestibility), these plants may still play a significant role as drought forage to provide feed when other forage sources are in limited supply. Further research is required to quantify the potential of Dorycnium species for commercial release and to determine how these plants should be best managed and integrated into livestock and mixed cropping systems.