秸秆覆盖是被广泛采用的减少侵蚀土壤碳流失的方法。然而，秸秆覆盖对黑土可溶性有机质（DOM）径流损失的影响尚未被深入研究。当前，秸秆覆盖通过改变土壤团聚体来影响径流DOM组成和损失的机制仍未明晰。本文对东北黑土区坡耕地秸秆覆盖处理和不覆盖处理（对照）进行了对比研究。我们将土壤筛分为大团聚体（>2 mm）、小团聚体（0.25–2 mm）和微团聚体（<0.25 mm）。在五次降雨发生后，分析了秸秆覆盖对径流和土壤团聚体中的DOM浓度（以可溶性有机碳含量表征）与组成（以荧光光谱分析）的影响。结果表明，秸秆覆盖减少了54.7%的径流量。因此，秸秆覆盖虽然增加了径流中平均可溶性有机碳（DOC）的浓度，但却减少了径流中48.3%的DOC损失。径流DOM的组成与土壤相似，都包含类腐殖酸和类蛋白质物质组分。秸秆覆盖处理后，随着降雨事件的发生，小团聚体中的类蛋白质成分积累，径流中的类蛋白质成分减少。荧光光谱技术可以通过捕捉径流和土壤DOM特征的动态变化，来了解降雨事件下物质迁移的水文路径。方差分解分析（VPA）表明，微团聚体解释了不覆盖处理下68.2%的地表径流DOM变化，而小团聚体解释了秸秆覆盖处理下55.1%的地表径流DOM变化。结果表明，秸秆覆盖减少了土壤小团聚体的破碎和微团聚体的损失，从而影响了土壤中DOM的组成、减少了径流中DOM的损失。本研究结果为坡耕地碳流失的阻控提供了理论依据。

本研究以矮化梨品种‘601D’及其突变体‘601T’为材料，研究比较了它们的生物学特性，并进一步探讨了601D的矮化机理。生物学特性表明，601D的节间短，树体短而紧凑，叶片厚而宽，气孔密度低，气孔（直径）大，光合能力强。601T的生物学特性表现出显著的差异。内源激素检测结果表明，601D的脱落酸（ABA）、ABA葡萄糖酯和GA4含量较高，而反式玉米素含量较低。通过转录组学分析，发现ABA的生物合成和代谢途径存在显著差异。相关转录因子如bHLH、WRKY和Homeobox等也参与了植物矮化的调控。因此，我们研究了三种与601T有明显差异的激素，发现只有ABA可以诱导601T恢复矮化植株表型。因此，我们认为601D的矮化是由于ABA的过度积累所致。本研究为矮化品种的选育提供了新的理论依据。

Heat stress seriously affects wheat production in many regions of the world.  At present, heat tolerance research remains one of the least understood fields in wheat genetics and breeding and there is a lack of effective methods to quantify heat stress and heat tolerance in different wheat cultivars.  The objective of this study was to use various wheat cultivars to evaluate stress intensity (δ) and a new method for quantification of heat tolerance and compare this technique with three other currently utilized methods.  This new parameter for heat tolerance quantification is referred to as the heat tolerance index (HTI) and is an indicator of both yield potential and yield stability.  Heat treatments were applied in a controlled setting when anthesis had been reached for 80% of the wheat.  The stress intensity evaluation indicated heat shock was the main factor associated with kernel weight reduction while grain yield reduction was mainly associated with chronic high temperature.  The methods evaluation showed that a temperature difference of 5°C from natural temperatures was a suitable heat treatment to compare to the untreated controls.  HTI was positively correlated with yield under heat stress (r=0.8657, δ₂₀₁₀=0.15, in 2009–2010; r=0.8418, δ₂₀₁₁=0.20, in 2010–2011; P<0.01), and negatively correlated with yield reduction rate (r=–0.8344, in 2009–2010; r=–0.7158, in 2010–2011; P<0.01).  The results of this study validated the use of HTI and temperature difference control for quantifying wheat heat tolerance that included the yield potential and the stability of different wheat cultivars under heat stress.  Additionally, 10 wheat cultivars showed high HTI and should be further tested for their heat confirming characteristics for use in wheat heat tolerance breeding.

Citrus canker, an epidemic quarantine disease caused by Xanthomonas axonopodis pv. citri, has brought a great damage in citrus production worldwide. Herein, a rice PRR (pattern recognition receptor) gene Xa21 together with GUS reporter gene and hygromycin phosphotransferase gene (HPT) was introduced into Anliucheng sweet orange (Citrus sinensis Osbeck) via Agrobacterium-mediated transformation of embryogenic callus. The transgenic calluses were screened on MT basal medium containing hygromycin (HYG) and detected by histochemical GUS staining. The transgenic plantlets were recovered through somatic embryogenesis pathway. The regenerated plantlets were accustomed to and maintained in the greenhouse. The transgene integration of recovered plantlets was identified by PCR and Southern blot hybridization. It showed that all the transgenic plantlets tested had undergone single copy integration, the expression of Xa21 in eight different transgenic lines detected by qRT-PCR can be divided into three grades, high for T5 and T6, middle for T4 and low for the rest. The tolerance to citrus canker disease of the three recovered transgenic lines T2, T4 and T6 was assessed by in vitro pin-puncture inoculation. The results showed that all the three transgenic lines conferred improved resistance to citrus canker bacterium infection and the T4 transgenic line displayed the highest resistance. The mechanism and feasibility of rice Xa21 in triggering innate immunity in citrus was briefly discussed.

Stalk related traits, comprising plant height (PH), ear height (EH), internode number (IN), average internode length (AIL), stalk diameter (SD), and ear height coefficient (EHC), are significantly correlated with yield, density tolerance, and lodging resistance in maize. To investigate the genetic basis for stalk related traits, a doubled haploid (DH) population derived from a cross between NX531 and NX110 were evauluated under two densities over 2 yr. The additive quantitative trait loci (QTLs), epistatic QTLs were detected using inclusive composite interval mapping and QTL-by-environment interaction were detected using mixed linear model. Differences between the two densities were significant for the six traits in the DH population. A linkage map that covered 1 721.19 cM with an average interval of 10.50 cM was constructed with 164 simple sequence repeat (SSR). Two, two, seven, six, two, and eight additive QTLs for PH, IN, AIL, EH, SD, and EHC, respectively. The extend of their contribution to penotypic variation ranged from 10.10 to 31.93%. Seven QTLs were indentified simultaneously under both densities. One pair, two pairs and one pair of epistatic effects were detected for AIL, SD and EHC, respectively. No epistatic effects were detected for PH, EH, and IN. Nineteen QTLs with environment interactions were detected and their contribution to phenotypic variation ranged from 0.43 to 1.89%. Some QTLs were stably detected under different environments or genetic backgrounds comparing with previous studies. These QTLs could be useful for genetic improvement of stalk related traits in maize breeding.