To describe the influence of different pecan seedling rootstocks on drought stress resistance, 12 rootstocks of ‘87MX1-2.2’, ‘87MX5-1.7’, ‘Elliott’, ‘Frutoso’, ‘Giles’, ‘Major’, ‘Moore’, ‘Peruque’, ‘Posey’, ‘Riverside’, ‘San Felipe’, and ‘VC1-68’ were selected as rootstock treatments for grafting. In addition, the experimental materials for the grafted young ‘Pawnee’ tree treatments included the pressure-volume technique (PV technique) and cutting shoot transpiration methods to plot the PV and the cutting shoot transpiration curves, and the parameters calculated from the two curves were used to analyze the data produced by the subordinate function and cluster dendrogram methods. The results revealed that the different seedling rootstock treatments influenced the ‘Pawnee’ grafted trees to varying degrees on aspects of drought resistance, the ability to save water, the modulation of osmosis, and the sensitivity of the stomatal response. The order of drought tolerance for these different pecan seedling rootstock treatments from high to low was as follows: ‘Posey’, ‘Peruque’, ‘Riverside’, ‘87MX5-1.7’, ‘VC1-68’, ‘Elliott’, ‘87MX1-2.2’, ‘San Felipe’, ‘Moore’, ‘Major’, ‘Giles’, and ‘Frutoso’.
Fan Cao, Yunchu Wei, Xinwang Wang, Yongrong Li, and Fangren Peng
Fan Cao, Xinwang Wang, Zhuangzhuang Liu, Yongrong Li, and Fangren Peng
Pecan cuttings are difficult for rooting. This study describes the pecan hardwood rooting process based on anatomic characteristics to understand root formation mechanisms of pecan cuttings. The expressed proteins of different periods during the adventitious rooting process of pecan seedling hardwood cuttings were identified and analyzed to evaluate the rooting mechanism. The expressed proteins of pecan cutting seedlings were also compared with other cultivar cuttings during the rooting period. Pecan seedling cuttings were developed at different air and substrate temperatures to induce root formation. Adventitious root formation of pecan hardwood cuttings was described, and the phloem at the base of the prepared cuttings was selected as the sample for the differential protein analysis. The results showed that adventitious root formation of pecan hardwood cuttings was the only product of callus differentiation, which originated from the cells of the cambium or vascular ray parenchyma. Such adventitious root primordia were developed from those calluses that formed the regenerative structure, and the expressed proteins during the adventitious rooting of pecan hardwood cutting were identified and analyzed by matrix-assisted laser desorption ionization–time of flight–mass spectrometry (MALDI-TOF-MS) to evaluate the rooting mechanism. Eight differentially expressed proteins were found in the rooting periods, and 15 differential proteins were found by comparing pecan cutting types, which were analyzed by peptide mass fingerprinting homology. The results show that the primordial cells were differentiated from the meristematic cells. Furthermore, the differentially expressed proteins contained energy metabolism proteins, adversity stress proteins, and signal transmission proteins. The energy metabolism-related proteins were adenosine triphosphate (ATP) synthase, photosynthesis-related proteins, and enolase. The adversity-stress proteins containing heat shock-related proteins and signal transmission proteins were mainly cytochrome enzymes and heme-binding proteins. Adventitious root formation of pecan cultivar hardwood cuttings was difficult. More trials should be performed from the potential aspects of high defensive protection and phloem morphologic structure.
Ting Zhou, Hao Jiang, Donglin Zhang, Junjun Fan, Long Zhang, Guibin Wang, Wangxiang Zhang, and Fuliang Cao
Junjun Fan, Wangxiang Zhang, Donglin Zhang, Ting Zhou, Hao Jiang, Guibin Wang, and Fuliang Cao
Ting Zhou, Hao Jiang, Wangxiang Zhang, Donglin Zhang, Junjun Fan, Quanquan Zhang, Guibin Wang, and Fuliang Cao
Zhuping Fan, Yike Gao, Ling Guo, Ying Cao, Rong Liu, and Qixiang Zhang
Bearded iris (Iris ×hybrida Hort.) is a large horticultural hybrid complex in the Iris genus, and the lack of understanding about its inheritance laws has seriously hindered the breeding process. From parental bearded iris ‘Indian Chief’ and ‘Sugar Blues’, four hybrid populations—including F1, F2, BC1P1, and BC1P2—were generated through hybridization. Fifteen key phenotypic traits, including plant height (PH), scape height (SH), length of fall (LF), width of fall (WF), length of standard (LS), width of standard (WS), and so on, were measured, and several genetic parameters (e.g., trait variation, heritability, trait correlation, distribution of flower color) were analyzed. The variation of phenotypic traits indicated that the F1 generation could produce larger flowers and a greater number of blooming stems than other generations, whereas backcrossing was beneficial at producing more flowers on one scape in the offspring of ‘Indian Chief’ and ‘Sugar Blues’. WF had the greatest broad-sense heritability (73.91%) among the 15 phenotypic traits, whereas the broad-sense heritability of SH was the lowest (2.06%). The correlation between a vegetative trait (PH) and a reproductive trait (WS) provided a path to early selection of germplasm. Furthermore, four important floral traits (LF, WF, LS, and WS) also correlated significantly to each other, thus simplifying the selection of larger flowers. Genes regulating fuchsia flower color were dominant over those for bluish purple flowers. Genetic effects of flower color in recurrent parents could be reinforced by backcrossing, thereby providing a potential way to modify flower color through hybridization.
Qiang Xiao, XiaoHui Fan, XiaoHui Ni, LiXia Li, GuoYuan Zou, and Bing Cao
Increasing commercial use of controlled release fertilizer (CRF) has prompted the need to predict N release simply and viably in the greenhouse environment. Two CRFs were tested, i.e., P40d and P100d by incubating them for 40 or 100 days either in static water at 10, 15, 20, 25, and 35 °C or in the soil of vegetable plots in a greenhouse lacking temperature controls. Cumulative nitrogen release (CNR) from a CRF was represented by a parabola curve and significantly affected by the incubation temperature. A method to calculate N m (the maximum N release percentage from CRF) was established using a first-order kinetic equation and the method of least squares. N m was 90.9% to 99.9% for P40d and 72.1% to 87.1% for P100d at 10–35 °C, respectively. A relationship function between the N release rate and naturally fluctuating greenhouse soil temperatures was established using the activation energy of the N release reaction. Then a model was constructed with field temperature as the variable to predict N release throughout the entire greenhouse crop production season. The value of ψ representing a property of the coating material of a CRF is ≈ 1.0 for the release period of the CRF of 35–55 days and ≈ 1.2 of 80–120 days. We validated the model using two seasons of greenhouse tomato, Solanum lycopersicum L., and cucumber, Cucumis sativus L., production data, and found that the error was less than 12% points. This indicated that the constructed model was sufficiently simple, practical, and accurate for use by growers, and fertilizer industry and regulatory personnel.
Guangtian Cao, Tingting Song, Yingyue Shen, Qunli Jin, Weilin Feng, Lijun Fan, and Weiming Cai
The Agaricus genus represents the most popular edible mushroom in the world. Wheat straw often is used as the substrate for mushroom cultivation following pretreatment to degrade the lignocellulosic biomass in agricultural waste. In this study, we investigated the changes in bacterial and fungal microflora of wheat straw substrate during different phases of composting. We collected samples of the raw material (M1), phase I aerobic fermentation (F1, F2, F3), and phase II after-fermentation (AF1) for high-throughput 16S rRNA and internal transcribed spacer (ITS) sequencing to analyze the microbial diversity in the substrate during composting. Our data revealed that among the five stages, 365 operational taxonomic units (OTUs) were shared, with Firmicutes, Proteobacteria, and Actinobacteria being the predominant bacterial phyla. In addition, Thermobispora, Thermopolyspora, Ruminiclostridium, Thermobacillus, and Bacillus were the predominant genera in F3 and AF1, with the species Thermobispora bispora and Pseudoxanthomonas taiwanensis being predominant in F2. Both principal component analysis (PCA) and nonmetric multidimensional scaling (NMDS) plots showed that the bacterial communities of five stages could be distinguished from each other based on their composting time. The Shannon and Simpson indexes of F2 were lower than M1 (P < 0.05), and the clustering dendrogram showed that the bacterial communities in AF1 were similar to F3, with Micromonosporaceae, Streptosporaceae, Thermomonosporaceae, and Vulgatibacteraceae representing the differential bacterial families by linear discriminant analysis with effect size (LEfSe) analysis. The analysis of fungal communities showed that 384 OTUs were common among the five stages, with 1054 and 454 OTUs unique to M1 and AF1, respectively. Ascomycota and Basidiomycota were the two predominant phyla in all stages, and Chytridiomycota was predominant in F2, F3, and AF1 stages. PCA and NMDS plots showed that the clusters of F2 and AF1 were more dispersed than the other stages. No differences were observed in alpha diversity between the stages, and samples of F1, F2, and F3 were closer to AF1 in the clustering dendrogram. By LEfSe analysis, Mycothermus thermophilus, Gonapodya polymorpha, and Phaeophleospora_eugeniae were identified as the predominant fungal species in AF1.
Fan Cao, Cong Guo, Ling Wu, Xin Huang, Qiuxia Xu, and Yujuan Li
Rui Zhang, Fang-Ren Peng, Pan Yan, Fan Cao, Zhuang-Zhuang Liu, Dong-Liang Le, and Peng-Peng Tan
Root systems of pecan trees are usually dominated by a single taproot with few lateral roots, which are commonly thought to inhibit successful transplanting. This study aimed to evaluate early growth and root/shoot development of pecan seedlings in response to taproot pruning. Taproots of ‘Shaoxing’ seedling pecan trees were mildly (1/3 of the total length of the radicle removed) and severely (2/3 of the total length of the radicle removed) pruned at different seedling development stages shortly after germination. At the end of the first growing season, top growth was measured and then trees were uprooted so that root system regrowth could be evaluated. The results showed that root pruning had no impact on increases in stem height or stem diameter. However, pruning the taproot could stimulate primary growth in taproot branches. Root weight and the number of taproot branches per tree increased with decreasing taproot length. This study indicated that severe root pruning when three to five leaves had emerged resulted in root systems with more taproot branches and the greatest root dry weight after one growth season, which may increase survival and reduce transplanting shock.