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A long-term field experiment was conducted over a twenty year period to examine the effects of three different soil management regimes (Abandonment, Fallow and Cropping) and eight nutrient management regimes under Cropping on soil organic carbon (SOC), N and P levels, microbial biomass, and enzymatic activities related to C, N, and P cycling in a loess soil. The nutrient management regimes examined involved treatment with various combinations of inorganic nitrogen, phosphorus, and potassium fertilizers (N, NP, PK, and NPK), as well as combinations of NPK fertilizers with either residual plant material (SNPK) or manure (MN1PK and MN2PK). Abandonment resulted in greater levels of soil microbial biomass than did Cropping but similar levels of enzyme activity were observed under both regimes. The Fallow regime gave significantly lower soil organic carbon levels and enzyme activities than did Cropping. Within the Cropping system, the treatments containning nitrogen and phophorus significantly improved SOC, N and P levels and also increased microbial biomass and enzyme activity relative to the control. In general, the highest values of the tested soil parameters were observed under the M2NPK treatment. With the exception of invertase, the activity of all soil enzymes tested correlated significantly with SOC and microbial biomass. It was concluded that the use of fertilization regimes involving applying organic material in conjunction with NPK fertilizers should be encouraged in order to maintain or improve the chemical and biological properties of the tested loess soil and to thereby increase its productivity.

The common walnut (or Persian walnut), Juglans regia L., is an economically important temperate tree species valued for both its edible nut and high-quality wood. F-box gene family members are involved in plant development, which includes regulating plant development, reproduction, cellular protein degradation, response to biotic and abiotic stresses, and flowering. However, in common walnut (J. regia), there are no reports about the F-box gene family. Here, we report a genome-wide identification of J. regia F-box genes and analyze their phylogeny, duplication, microRNA, pathway, and transcriptional expression profile. In this study, 74 F-box genes were identified and clustered into three groups based on phylogenetic analysis and eight subfamilies based on special domains in common walnut. These common walnut F-box genes are distributed on 31 different pseudo-chromosomes. The gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and microRNA profiles showed that the F-box gene family might play a critical role in the flowering of common walnut. The expressions were significantly higher in female flowers and male flowers compared with leaf and hull tissues at a transcriptome level. The results revealed that the expressions of the F-box gene in female flowers were positively correlated with male flowers, but there was no correlation between any other tissue combinations in common walnut. Our results provided insight into the general characteristics of the F-box genes in common walnut.

ABSTRACT. BAK1 is a co-receptor of BRI1 in early signaling pathways mediated by brassinosteroids (BRs) and is thought to play a major role in plant growth and development. As the role of BAK1 has not yet been fully elucidated then further research is required to explore its potential for use in genetic modification to improve crops. In this study, three BAK1 genes from the amphidiploid species Brassica rapa were isolated and their kinase functions were predicted following DNA sequence analysis. A bioinformatic analysis revealed that two genes, BrBAK1-1 and BrBAK1-8, shared a conserved kinase domain and 5 tandem leucine-rich repeats (LRRs) that are characteristic of a BAK1 receptor for BR perception, whereas the third gene, BrBAK1-3, was deficient for a signal peptide, but had 4 leucine zippers and 3 leucine-rich repeats (LRRs) in an extracellular domain. All three BrBAK1 kinases localized on the cellular membrane. Ectopic expression of each BrBAK1 gene in BR-insensitive (bri1-5 mutant) Arabidopsis plants indicated that BrBAK1-1 and BrBAK1-8 were functional homologues of AtBAK1 based on the rescue of growth in the bri1-5 mutant. Overexpression of BrBAK1-3 caused a severe dwarf phenotype resembling the phenotype of null BRI1 alleles. The results here suggest there are significant differences among the three BrBAK1 kinases for their effects on plant architecture. This conclusion has important implications for genetic modification of B. rapa.

Background:Agroforestry system is regarded as a promising practice in sustainable agricultural management. However, the effects of long-term tree-based intercropping on crop remain poorly understood, especially in the Loess Plateau. In this study, the impacts of photosynthetic and respiration rate were determined by the portable photosynthesis system (Li-6400), and the effects of the root growth dynamics of soybean in walnut-soybean intercropping system were measured by soil auger and WinRHIZO root analysis system, in the Loess Plateau. Results:The results showed that soybean reached the highest net photosynthetic rate during flowering period, with the net photosynthetic rate of intercropped soybean, which was 20.40µmol·m-2·s-1, significantly higher than that of its monocropped counterpart. Soybean biomass reached the maximum during the pod-bearing period, with intercropped soybean biomass being 25.49g, significantly higher than that of its monocropped counterpart. The mean diameter and increased density of soybean fine roots reduced along with increased soil depth. Both the diameter (0.43mm) and increased density (930cm/dm3) of intercropped soybean fine roots were evidently higher than those of monocropped soybean(0.35mm, 780cm/dm3). With increasing cropping years, fine roots of intercropped soybean tended to be mainly distributed in soil at a depth between 0 and 20cm from the fifth year. Conclusion:Collectively, compared with soybean monoculture, walnut soybean agroforestry system is more conducive to soybean growth in the Loess Plateau.