One of the ways to reduce chemical fertilizer application is the use of cover crops, which improve soil properties and supply nutrition to subsequent crops. The application effect of a legume cover crop, hairy vetch (Vicia villosa R., HV), on N dynamics in fresh market tomatoes (Solanum lycopersicum L.), 'House Momotaro,' was investigated using the 15 N-labeling method. Tomato seedlings were transplanted into a 1/2000 a Wagner pot at 0, 80, and 240 kg·ha −1 of N application (N0HV, N80HV, and N240HV) on June 9, 2011. Before transplanting, the labeled HV and chemical fertilizers were incorporated into the soil. Five tomato plants were collected 6 times in each treatment and then separated into leaves, stems, and roots. Fruits were harvested at maturity. HV-derived N uptake was recognized mainly in the first 4 weeks after transplant (WAT). Especially in N240HV, HV-derived N uptake ceased at 4 WAT. The uptake amounts of HV-derived N at 10 WAT were 587, 657, and 729 mg·plant −1 in N240HV, N80HV, and N0HV, respectively, and were increased by decreasing N fertilizer application. The rate of N uptake derived from HV to total N uptake in tomato plants (%N dfhv ) was the highest at 2 WAT, and %N dfhv in N80HV (52.1%) and N0HV (51.5%) were significantly higher than in N240HV (43.6%). After 2 WAT, %N dfhv decreased gradually in all N rates as tomatoes grew and decreased to 24.8%, 34.4%, and 37.1% in N240HV, N80HV, and N0HV, respectively, until 12 WAT. Nitrogen use efficiency (NUE) from HV-derived N was the highest at 10 WAT, and N0HV (55.3%) was significantly higher than N240HV (44.5%) and N80HV (49.8%). The partition rate of HVderived N into fruits was 63.9%, and 39.7% of HV-derived N was distributed into 1st and 2nd fruit clusters. From these results, it was clarified that HV can be expected to be an alternative N fertilizer because HV-derived N was absorbed effectively with a small amount of N fertilizer. Further research on fertilizer management in tomato's early stage will be needed for an N-reduction system because HV-derived N was mainly absorbed for 4 WAT.

This is the first report on association analysis of salt tolerance and identification of SNP markers associated with salt tolerance in cowpea. Cowpea (Vigna unguiculata (L.) Walp) is one of the most important cultivated legumes in Africa. The worldwide annual production in cowpea dry seed is 5.4 million metric tons. However, cowpea is unfavorably affected by salinity stress at germination and seedling stages, which is exacerbated by the effects of climate change. The lack of knowledge on the genetic underlying salt tolerance in cowpea limits the establishment of a breeding strategy for developing salt-tolerant cowpea cultivars. The objectives of this study were to conduct association mapping for salt tolerance at germination and seedling stages and to identify SNP markers associated with salt tolerance in cowpea. We analyzed the salt tolerance index of 116 and 155 cowpea accessions at germination and seedling stages, respectively. A total of 1049 SNPs postulated from genotyping-by-sequencing were used for association analysis. Population structure was inferred using Structure 2.3.4; K optimal was determined using Structure Harvester. TASSEL 5, GAPIT, and FarmCPU involving three models such as single marker regression, general linear model, and mixed linear model were used for the association study. Substantial variation in salt tolerance index for germination rate, plant height reduction, fresh and dry shoot biomass reduction, foliar leaf injury, and inhibition of the first trifoliate leaf was observed. The cowpea accessions were structured into two subpopulations. Three SNPs, Scaffold87490_622, Scaffold87490_630, and C35017374_128 were highly associated with salt tolerance at germination stage. Seven SNPs, Scaffold93827_270, Scaffold68489_600, Scaffold87490_633, Scaffold87490_640, Scaffold82042_3387, C35069468_1916, and Scaffold93942_1089 were found to be associated with salt tolerance at seedling stage. The SNP markers were consistent across the three models and could be used as a tool to select salt-tolerant lines for breeding improved cowpea tolerance to salinity.

Utilization of cover crops helps the establishment of environmentally friendly agriculture due to their nutrition supplying ability mainly in the current year of application, but cover crop-derived N also remains until the following year. In the present study, the nutritional effect of a cover crop on tomato production in a greenhouse in the following year was investigated using the

In order to improve the use efficiency of a cover crop, hairy vetch (Vicia villosa R., HV), and supplemental chemical N fertilizer, N release and uptake patterns from HV, fast-release N fertilizer (Fast), and slow-release N fertilizer (Slow) in fresh market tomato (Solanum lycopersicum L.) production were investigated using the 15 N-labeling method. In the incubation of soil-added N at two mix rates, 20% Fast + 80% Slow (

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