Root-knot nematodes (Meloidogyne spp.) have garnered significant attention from researchers owing to the substantial damage they cause to crops and their worldwide distribution. However, controlling these nematodes is challenging because a limited number of chemical pesticides and biocontrol agents are effective against them. Here, we demonstrate that pepper rotation markedly reduces Meloidogyne incognita infection in cucumber and diminishes the presence of p-hydroxybenzoic acid in the soil, a compound known to exacerbate M. incognita infection. Pepper rotation also restructures the rhizobacterial community, leading to the colonization of the cucumber rhizosphere by two Pseudarthrobacter oxydans strains (RH60 and RH97), facilitated by enrichment of palmitic acid in pepper root exudates. Both strains exhibit high nematocidal activity against M. incognita and have the ability to biosynthesize indoleacetic acid and biodegrade p-hydroxybenzoic acid. RH60 and RH97 also induce systemic resistance in cucumber plants and promote their growth. These data suggest that the pepper root exudate palmitic acid alleviates M. incognita infection by recruiting beneficial P. oxydans to the cucumber rhizosphere. Our analyses identify a novel chemical component in root exudates and reveal its pivotal role in crop rotation for disease control, providing intriguing insights into the keystone function of root exudates in plant protection against root-knot nematode infection.

An important reserve for increasing the productivity of agricultural production is a scientifically based crop structure and the use of rational crop rotations, which implement the optimal ratio of agroecological standards. The aim of the research was to determine the influence of elements of agrotechnical measures, in particular, the saturation of crop rotations with sunflower, soil tillage system on the number and species composition of various agrobiological groups of weeds in sunflower crops, including the weed parasite sunflower broomrape (Orobanche cumana Wallr.). Weed control measures and the spread of the parasitic weed sunflower broomrape in sunflower crops have been carried out according to the methods generally accepted in agriculture and weed science. The scheme of the experiment included crop rotations with saturation in the structure of sunflower sowing of 12.5, 20, 25, 33.3, 50, 100% and three systems of basic tillage: moldboard plowing, disc tillage, and no-tillage. As a result of the research, it has been found that the systems of disc tillage and no-tillage cause an increase in the number of weeds in sunflower crops compared to the moldboard plowing by 1.3-1.5 times. On average, over the years of research, the abundance of weeds in the plots when using disk tools was 10.4-15.1 pcs./m(2), moldboard plowing was 7.1-12.4 pcs./m(2), and before harvesting was 2.6-5.2 and 4.1-12.4 pcs./m(2). The highest degree of sunflower broomrape damage has been observed in 2-fields crop rotation (winter wheat-sunflower) and permanent sunflower cultivation, as 16.0-32.4% of affected sunflower plants have been observed here. The intensity of sunflower broomrape damage to sunflower plants was higher in the moldboard plowing system and amounted to 1.2-8.3 pcs./per plant, which exceeded disc tillage and no-tillage by 1.2-1.6 times. The maximum seed yield of 2.92-2.95 t/ha has been obtained in 8- and 5-fields rotations with the use of moldboard plowing. The lowest yields of sunflower seeds were in short-rotation crop rotations with a sunflower saturation of 50% in the structure of sown areas and permanent cultivation and amounted to: moldboard plowing-1.75-2.21 t/ha, disk tillage-1.57-2.01 t/ha, and no-tillage-1.49-1.95 t/ha. Given the urgency of supplying the global market with sunflower oil, in the future it is necessary to increase the concentration of sunflower in the structure of sown areas to 30-40% through the system of basic tillage, selection of resistant hybrids, and use of herbicides. Preview

Long-term continuous cropping affects the soil microecological community and leads to nutrient imbalances, which reduces crop yields, and crop rotation can increase soil productivity. To study the effects of the cultivation of tomato (Solanum lycopersicum) and corn (Zea mays) on the microbial community, physical and chemical factors and the structure of aggregates in cotton (Gossypium hirsutum) long-term continuous cropping soils were examined. Four cropping patterns were established, including one continuous cropping pattern and three crop rotation patterns, and the diversity of the soil microecological community was measured using high-throughput sequencing. The physical and chemical properties of different models of soil were measured, and the soil aggregate structure was determined by dry and wet sieving. Planting of aftercrop tomato and corn altered the bacterial community of the cotton continuous soil to a lesser extent and the fungal community to a greater extent. In addition, continuous cropping reduced the diversity and richness of the soil fungal community. Different aftercrop planting patterns showed that there were very high contents of soil organic carbon and organic matter in the cotton-maize rotation model, while the soil aggregate structure was the most stable in the corn-cotton rotation model. Planting tomato in continuous cropping cotton fields has a greater effect on the soil microbial community than planting maize. Therefore, according to the characteristics of different succeeding crop planting patterns, the damage of continuous cropping of cotton to the soil microenvironment can be alleviated directionally, which will enable the sustainable development of cotton production.

BackgroundMalnutrition is one of the major health concerns, particularly in the developing and under-developed world. In South Africa, maize is produced as a staple food and is the primary food for most of the country's population. The North-Western Free State which forms part of the Nala municipality in the Lejweleputswa district of South Africa is a main producer of the country's maize. However, the area is known for its sandy soil which contains little organic material, silt and clay. Maize in this area is normally grown in monoculture but with a focus on sustainable agriculture has recently incorporated soybean. As a means of fighting malnutrition, the objective of this study was to determine the influence that soybean incorporation as a rotation crop has on the nutritional value of maize.MethodsA trial was conducted on the farm Christinasrus in the North-Western Free State to compare the nutritional value of monoculture maize and maize in rotation with soybean over three consecutive seasons. Maize kernel samples were taken each season and its nutritional properties analyzed. Subsequent data were further analyzed using statistical analysis.ResultsResults showed that there was a seasonal effect on all nutritional properties with a general decrease in nutritional values in wetter years. Cropping systems had an effect on fibre content, with increased values observed in maize after soybean. In addition, there was a significant interaction between season and cropping systems on the total digestible nutritional value, with maize after soybean being more nutritious in wetter seasons.ConclusionResults suggest that maize in cropping systems with soybean has potential to be more nutritious while the soybean in the cropping system can act as a protein-rich companion, providing a more balanced diet for human consumption, thereby fighting malnutrition.