茶树是中国主要经济作物之一，安徽省茶树栽培历史悠久具有丰富的种质资源和遗传多样性。茶树的高度杂合性导致其种质资源收集、管理及保护等方面工作进展缓慢，并且长期保存管理成本高，因此提高安徽省茶树种质资源的管理质量和效率，构建核心种质迫在眉睫。本研究从安徽省6个主要产茶地区收集了573份有代表性的茶树，基于60对SSR分子标记进行系统发育关系、群体结构和主坐标分析。聚类结果显示，安徽省573份茶树被分为5个类群，这些类群分布地区与收集样品的地理位置相关，聚类结果与PCoA的分群结果也基本一致。最后，我们构建了一个由115份茶树品种组成的核心种质，占原始种质的20%。核心种质中观察到的等位基因数(Na)具有90.9%的保留率，并且核心种质和原始种质的香农信息指数(I)及其他遗传多样性参数之间没有显著性差异。所有代表性茶区均保留了部分代表性品种，其中黄山地区保留了39份茶树，占核心种质的33.9%；金寨县保留了10份茶树，占核心种质的8.9%。PCoA结果表明构建的核心种质均匀的分布在收集的安徽省茶树种质中，说明构建的核心种质能够代表安徽省茶树种质的遗传多样性。本研究对安徽省茶树种质资源的高效保存和利用具有一定的参考价值。

栽培草莓（Fragaria×ananassa）来自四个二倍体祖先：F. vesca，F. viridis，F .iinumae和F. nipponica。其中，F. vesca是栽培草莓最主要的亚基因组。目前，基因表达如何促进二倍体和八倍体草莓之间的果实发育过程中的差异的机制沿不清楚。在这里，我们对F. vesca和F.×ananassa的转录组进行全面分析，以研究水果发育不同阶段的基因表达。通过二倍体和八倍体之间的成对比较，我们总共获得了3,741个（转色期）和3,960个（成熟期）差异表达的基因。类黄酮生物合成中涉及的基因在八倍体的转色阶段被显著上调，并且我们还通过加权共表达网络（WGCNA）分析发现了与几种类黄酮生物合成基因（包括FveMYB10，FveMYB9/11和FveRAP）相关的成熟果实特异性模块。此外，我们确定了八倍体和二倍体果实中的物种特异调控网络。值得注意的是，我们发现WAK和F-box基因分别在八倍体和二倍体果实中富集。总体而言，这项研究有助于阐明草莓的类黄酮生物合成和果实大小，这对栽培草莓的未来分子育种具有重要意义。

植被覆盖度(FVC)是衡量作物生长状况的重要指标。在作物生长监测研究中，快速、准确地提取植被覆盖度非常重要。摄影法是目前应用最广泛的FVC提取方法，具有操作简单、提取精度高的优点。但是，当土壤湿度和采集时间不同时，提取结果的准确度较差。为了适应不同的植被覆盖度提取条件，本文提出了一种新的植被覆盖度提取方法，该方法采用密度峰值K-means (density peak K-means, DPK-means)算法从小麦归一化差值植被指数(NDVI)灰度图像中提取植被覆盖度。本研究以盆栽种植的杨麦4 (YF4)和田间种植的杨麦16 (Y16)为研究对象，使用三脚架搭载高光谱成像相机，在盆栽小麦冠层上方1m处采集不同土壤条件(干、湿)下小麦的地面高光谱图像。无人机搭载高光谱相机，在田间小麦冠层上方50m高空采集不同时期的冬小麦高光谱图像。分别采用像元二分法和DPK-means算法对小麦NDVI灰度图像中的植被像元和非植被像元进行分类，并对两种方法的提取效果进行了比较分析。结果表明，像素二分法提取的图像受到采集条件的影响较大，误差分布较为分散。DPK-means算法的提取效果受采集条件的影响较小，误差分布比较集中。干、湿土壤条件和不同时间条件下的误差绝对值分别为0.042和0.044，均方根误差(RMSE)分别为0.028和0.030,FVC拟合精度R²分别为0.87和0.93。本研究表明，在不同土壤和时间条件下，DPK-means算法比像元二分法能够获得更准确的结果，是一种准确、稳健的FVC提取方法。

于极端降雨量事件的频繁发生，涝渍胁迫已成为粮食生产的明显制约因素。叶片含水量是一个重要的指标，且高光谱遥感为测定它提供了一种无损、实时且可靠的方法。因此，本文基于盆栽试验，于拔节期对冬小麦进行不同涝渍胁迫梯度处理。涝渍胁迫后每7天采集一次叶片高光谱数据、叶片含水量（leaf water content, LWC）数据，直至小麦成熟。结合植被指数构建、相关分析、回归分析、BP神经网络（BP neural network, BPNN）等方法，我们发现：（1）涝渍胁迫对叶片含水量的影响具有滞后性。（2）所有涝渍胁迫均会导致叶片含水量的降低。重度渍水下叶片含水量的下降速度比轻度渍水快，但长期轻度渍水比短期重度渍水对叶片含水量的影响程度更深。（3）叶片含水量的光谱敏感波段位于可见光（VIS, 400-780 nm）和短波红外（SWIR, 1400-2500 nm）波段。（4）以648 nm处原始光谱值，500 nm处一阶微分值，红边位置，新植被指数RVI (437, 466), NDVI (437, 466) 和NDVI' (747, 1956) 作为自变量建立的BPNN模型最适合反演涝渍胁迫冬小麦叶片含水量（建模集：R2=0.889, RMSE=0.138；验模集：R2=0.891, RMSE=0.518）。研究结果对涝渍胁迫精确防控具有重要的理论意义和实际应用价值。

Crop modelling can facilitate researchers’ ability to understand and interpret experimental results, and to diagnose yield gaps. In this paper, the Decision Support Systems for Agrotechnology Transfer 4.6 (DSSAT) model together with the CENTURT soil model were employed to investigate the effect of low nitrogen (N) input on wheat (Triticum aestivum L.) yield, grain N concentration and soil organic carbon (SOC) in a long-term experiment (19 years) under a wheat-maize (Zea mays L.) rotation at Changping, Beijing, China.  There were two treatments including N0 (no N application) and N150 (150 kg N ha^–1) before wheat and maize planting, with phosphorus (P) and potassium (K) basal fertilizers applied as 75 kg P₂O₅ ha^–1 and 37.5 kg K₂O ha^–1, respectively.  The DSSAT-CENTURY model was able to satisfactorily simulate measured wheat grain yield and grain N concentration at N0, but could not simulate these parameters at N150, or SOC in either N treatment.  Model simulation and field measurement showed that N application (N150) increased wheat yield compared to no N application (N0).  The results indicated that inorganic fertilizer application at the rates used did not maintain crop yield and SOC levels.  It is suggested that if the DSSAT is calibrated carefully, it can be a useful tool for assessing and predicting wheat yield, grain N concentration, and SOC trends under wheat-maize cropping systems.

Chinese chive usually develops an off-flavor after a short storage time.  To explore effective ways to maintain the postharvest quality of Chinese chive, the effect of exogenous application of 6-benzylaminopurine (6-BA) on postharvest quality and antioxidant activity of chive was evaluated, and the mechanism of the physiological responses of chive to 6-BA treatment was explored.  Chives were sprayed for 10 min with 100, 300, or 500 mg L^–1 6-BA or with alkaline solution as the control, then stored at (2±1)°C with a relative humidity (RH) of 80–85%.  We found that 300 mg L^–1 6-BA significantly delayed yellowing and chlorophyll degradation, maintained the total phenolic and flavonoid content, and improved the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD).  In conclusion, we identified exogenous application of 6-BA as an effective method for maintaining postharvest quality of Chinese chive.  In addition, our finding that the activities of antioxidant enzymes increase in response to exogenous 6-BA provides new insights into the mechanism of cytokinin-based postharvest fresh-keeping. 

Phosphorus (P) losses from agricultural soils contribute to eutrophication of surface waters. This field plot study investigated effects of rainfall regimes and P applications on P loss by surface runoff from rice (Oryza sativa L.) and wheat (Triticum aestivum L.) cropping systems in Lake Taihu region, China. The study was conducted on two types of paddy soils (Hydromorphic at Anzhen site, Wuxi City, and Degleyed at Xinzhuang site, Changshu City, Jiangsu Province) with different P status, and it covered 3 years with low, high and normal rainfall regimes. Four rates of mineral P fertilizer, i.e., no P (control), 30 kg P ha–1 for rice and 20 kg P ha–1 for wheat (P30+20), 75 plus 40 (P75+40), and 150 plus 80 (P150+80), were applied as treatments. Runoff water from individual plots and runoff events was recorded and analyzed for total P and dissolved reactive P concentrations. Losses of total P and dissolved reactive P significantly increased with rainfall depth and P rates (P<0.0001). Annual total P losses ranged from 0.36–0.92 kg ha–1 in control to 1.13–4.67 kg ha–1 in P150+80 at Anzhen, and correspondingly from 0.36–0.48 kg ha–1 to 1.26–1.88 kg ha–1 at Xinzhuang, with 16–49% of total P as dissolved reactive P. In particular, large amounts of P were lost during heavy rainfall events that occurred shortly after P applications at Anzhen. On average of all P treatments, rice growing season constituted 37–86% of annual total P loss at Anzhen and 28–44% of that at Xinzhuang. In both crop seasons, P concentrations peaked in the first runoff events and decreased with time. During rice growing season, runoff P concentrations positively correlated (P<0.0001) with P concentrations in field ponding water that was intentionally enclosed by construction of field bund. The relative high P loss during wheat growing season at Xinzhuang was due to high soil P status. In conclusion, P should be applied at rates balancing crop removal (20–30 kg P ha–1 in this study) and at time excluding heavy rains. Moreover, irrigation and drainage water should be appropriately managed to reduce runoff P losses from rice-wheat cropping systems.

Sufficient soil phosphorus (P) content is essential for achieving optimal crop yields, but accumulation of P in the soil due to excessive P applications can cause a risk of P loss and contribute to eutrophication of surface waters. Determination of a critical soil P value is fundamental for making appropriate P fertilization recommendations to ensure safety of both environment and crop production. In this study, agronomic and environmental critical P levels were determined by using linear-linear and linear-plateau models, and two segment linear model, for a maize (Zea mays L.)-winter wheat (Triticum aestivum L.) rotation system based on a 22-yr field experiment on a Haplic Luvisol soil in northern China. This study included six treatments: control (unfertilized), no P (NoP), application of mineral P fertilizer (MinP), MinP plus return of maize straw (MinP+StrP), MinP plus low rate of farmyard swine manure (MinP+L.Man) and MinP plus high rate of manure (MinP+ H.Man). Based on the two models, the mean agronomic critical levels of soil Olsen-P for optimal maize and wheat yields were 12.3 and 12.8 mg kg−1, respectively. The environmental critical P value as an indicator for P leaching was 30.6 mg Olsen-P kg−1, which was 2.4 times higher than the agronomic critical P value (on average 12.5 mg P kg−1). It was calculated that soil Olsen-P content would reach the environmental critical P value in 41 years in the MinP treatment, but in only 5–6 years in the two manure treatments. Application of manure could significantly raise soil Olsen-P content and cause an obvious risk of P leaching. In conclusion, the threshold range of soil Olsen-P is from 12.5 to 30.6 mg P kg−1 to optimize crop yields and meanwhile maintain relatively low risk of P leaching in Haplic Luvisol soil, northern China.

In this study, Aspergillus niger 1107 was isolated and identified as an efficient phosphate-solubilizing fungus (PSF). This strain generated 689 mg soluble P L–1 NBRIP medium after 10 d of culture. To produce an affordable biofertilizer using A. niger 1107, the potential of widely available carrier materials for growth and maintenance of this strain were evaluated. The effects of sterilization procedures (autoclaving and gamma-ray irradiation) on the suitability of these carriers to maintain growth of the fungus were also investigated. The carrier materials were peat, corn cobs with 20% (w/w) perlite (CCP), wheat husks with 20% (w/w) perlite (WHP), and composted cattle manure with 20% (w/w) perlite (CCMP). In the first 5-6 mon of storage, the carriers sterilized by gamma-ray irradiation maintained higher inoculum loads than those in carriers sterilized by autoclaving. However, this effect was not detectable after 7 mon of storage. For the P-biofertilizer on WHP, more than 2.0×107 viable spores of A. niger g–1 inoculant survived after 7 mon of storage. When this biofertilizer was applied to Chinese cabbage in a pot experiment, there were 5.6×106 spores of A. niger g–1 soil before plant harvesting. In the pot experiment, Chinese cabbage plants grown in soil treated with peat- and WHP-based P-biofertilizers showed significantly greater growth (P<0.05) than that of plants grown in soil treated with free-cell biofertilizer or the CCMP-based biofertilizer. Also, the peat- and WHP-based P-biofertilizers increased the available P content in soil.

Sesame (Sesamue indicum L.) is one of the most important oilseed crops with high oil yield. Here, we described a simpleand efficient method for constructing a normalized cDNA library from a high oil content cultivar of sesame Zhongzhi 14,during its oil accumulation stages. It combined switching mechanism at 5´-end of RNA transcript (SMART) technique andduplex-specific nuclease (DSN) normalization methods. Double-stranded cDNAs were synthesized from mRNAs, processedby normalization and Sfi I restriction endonuclease, and finally the cDNAs were ligated to pDNR-LIB vector. The ligationmixture was transformed into Escherichia coli DH10B by electroporation. The capacity of the library was 1.0×106 clonesin this library. Gel electrophoresis results indicated the fragments ranged from 700 to 2 000 bp, with the average size of1 800 bp. Random picking clones showed that the recombination rate was 100%. The results showed that the cDNA libraryconstructed successfully was a full-length library with high quality, and could be used to screen the genes related todevelopment of oil synthesis.