Crop disease remains a major problem to global food production. Excess use of pesticides through chemical disease control measures is a serious problem for sustainable agriculture as we struggle for higher crop productivity. The use of plant growth promoting rhizobacteria (PGPR) is a proven environment friendly way of controlling plant disease and increasing crop yield. PGPR suppress diseases by directly synthesizing pathogen-antagonizing compounds, as well as by triggering plant immune responses. It is possible to identify and develop PGPR that both suppress plant disease and more directly stimulate plant growth, bringing dual benefit. A number of PGPR have been registered for commercial use under greenhouse and field conditions and a large number of strains have been identified and proved as effective biocontrol agents (BCAs) under environmentally controlled conditions. However, there are still a number of challenges before registration, large-scale application, and adoption of PGPR for the pest and disease management. Successful BCAs provide strong theoretical and practical support for application of PGPR in greenhouse production, which ensures the feasibility and efficacy of PGPR for commercial horticulture production. This could be pave the way for widespread use of BCAs in agriculture, including under field conditions, to assist with both disease management and climate change conditions.

: Understanding the interaction between salinity and nitrogen (N) nutrition is of great economic importance to improve plant growth and grain yield for oat plants. The objective of this study was to investigate whether N application could alleviate the negative effect of salinity (NaCl) stress on oat physiological parameters and yield performance. Two oat genotypes with contrasting salt tolerance response (6-SA120097, a salt-tolerant genotype SA and 153-ND121147, salt-sensitive ND) were grown under four N rates (0, 100, 200, and 400 mg N pot−1) in non-saline and saline (100 mM NaCl) conditions. The results showed that salinity, N fertilization and their interaction significantly affected the photosynthetic rate, transpiration rate, agronomic nitrogen use efficiency (aNUE), physiological nitrogen efficiency (pNUE) and apparent nitrogen recovery (ANR), seed number, and grain yield. Saline stress reduced gas exchange rate, nitrogen use efficiency (NUE), grain yield, and yield components. N fertilization increased photosynthetic productivity and chlorophyll fluorescence, resulting in improved grain yields and yield components for both genotypes. On average, the photosynthetic rate was increased by 38.7%, 74.1%, and 98.8% for SA and by 49.8%, 77.6%, and 110% for ND, respectively, under the N rates of 100, 200, and 400 mg N pot−1, as compared with non-fertilized treatment. In addition, grain yield was increased by 80.6% for genotype SA and 88.7% for genotype ND under higher N application rate (200 mg N pot−1) in comparison with the non-nitrogen treatment. Our experimental results showed that an increase of N supply can alleviate the negative effects induced by salinity stress and improved plant growth and yield by maintaining the integrity of the photosynthesis and chlorophyll fluorescence processes of oat plants, which provides a valuable agronomic strategy for improving oat production in salt-affected soils.

Salinity limits germination and plant growth and development in 45 million ha worldwide. Techniques to overcome this problem are needed. This project investigated the effects of jasmonic acid (JA) (0, 5, and 10 mM JA) and humic acid (HA) (0, 3, and 6 g HA kg −1 soil) on growth and physiological parameters of forage sorghum (Sorghum bicolor L. Moench) under different NaCl salinity levels (0, 100, and 200 mM NaCl, with an equivalent electrical conductivity (EC) of 0.12 dSm −1 as control treatment, 3.22, and 5.78 dSm −1 , respectively). NaCl salinity reduced emergence percentage, emergence rate, salt tolerance index and seedling vigor index, all seedling growth parameters, ascorbate peroxidase (APX) activity, chlorophyll a, b and total chlorophyll content. Proline content and soluble protein content were increased with salinity. At the 200 mM salinity level, seeds treated with 10 mM JA had a positive effect on emergence percentage, emergence rate, shoot length, total fresh weight, salt tolerance index, seedling vigor index, chlorophyll a and total chlorophyll content. At 200 mM NaCl salinity level, seeds treated with 6 g HA kg −1 soil had increased root length, total dry weight, salt tolerance index, seedling vigor index, shoot length, protein content, APX, chlorophyll b, and total chlorophyll in seedlings. The application of 5 mM JA combined with 6 g HA kg −1 soil was most effective in minimizing salinity stress. Our study suggested that the appropriate combined application of HA and JA could efficiently protect early seedlings from salt stress damage and alleviate abiotic stress.Abbreviations: APX, ascorbate peroxidase; HA, humic acid; JA, jasmonic acid; ROS, reactive oxygen species.

No abstract