Effects of ammonium and inorganic carbon enrichment on growth and yield of a hydroponic tomato crop

Effects of varying the proportions of NO₃^— and NH₄⁺ in the growth medium on seedling growth and tomato fruit yield (Lycopersicon esculentum L. cv. Trust F1) were investigated in greenhouse hydroponic experiments. The presence of NH₄⁺ as the sole N source (11 mM) was toxic: it curtailed growth and decreased chlorophyll content of the leaves. However, at low concentration (10 % of total N), the presence of NH₄⁺, with or without added dissolved inorganic carbon (DIC), increased vegetative growth and fruit yield by ˜ 15 %, and enhanced taste/flavor of the fruits. In DIC‐enriched treatment, pH was maintained at 5.8 by addition of KHCO₃ or as CaCO₃. The presence of NH₄⁺, at 10 % of total N, inhibited NO₃^— uptake rates by ˜ 27 %. The rates of uptake of NO₃^— and NH₄⁺ were comparable (13.3 and 14.2 mmol plant^—1 d^—1, respectively, in the presence of DIC, and 14.7 and 14.0 mmol plant^—1 d^—1, respectively, in the absence of DIC), despite such a large difference in their concentrations in the nutrient feed solution. A higher proportion of NH₄⁺ (up to 50 % of total N) had no further significant effect upon early vegetative growth, but in a long‐term experiment resulted in a high incidence of blossom end‐rot (BER) disease, thereby severely curtailing fruit yield. The presence of even 1.1 mM NH₄⁺ reduced Ca²⁺ and Mg²⁺ accumulation in the leaves as well as in fruits.     

光照分布不均的米粒数目统计

通过对光照不均匀的米粒灰度图像进行最佳阈值分割和特征提取,获得对米粒数目的自动检测方法。该方法具有较强的光照分布不均和面积大小适应性。经仿真试验,检测结果可以达到97%以上。同时,相较于同类算法,该方法算法简单,运行时间较短。     

Analysis of a site x year experiment with timothy polycross progeny

Summary Results from a cooperative breeding programme with timothy for the northern areas of Scandinavia are presented. The main aim of the programme was to identify genotypes for synthetic populations that are high yielding, adapted over the whole area and stable over years. A polycross comprising 12 genotypes from each of five sites within the region was formed. The subsequent 60 half-sib families and four reference varieties were then compared under sward conditions at the same sites. The trials lasted for three years and results for total dry matter yields are presented.Significant differences in yield between lines were found. There were also significant two and three factor interactions between lines, sites and years. A new two-step procedure is presented to select the genotypes to make up a synthetic variety. Firstly, a superiority measure (Q-value) is used to select a group of genotypes that are high yielding and stable over sites and years. Secondly, the GxE part of the Q-value is split into two terms. One measures adaptation to predictable environmental conditions. The other one measures stability to unpredictable changes in the environment. A plot of these two measures provides a tool for discarding unstable or poorly adapted genotypes. The statistical properties of the selection parameters are discussed.     

Influence of temperature on the growth of bermudagrass selections from the Appalachian region

Abstract

The hilly terrain of the Appalachian region creates an environment in which large differences in soil temperature occur over a very short distance on the landscape. The ability of a grass to display adequate growth over a range of temperatures would greatly enhance its adaptability and use as a forage or for soil conservation. A growth chamber experiment was conducted to evaluate the influence of temperature on the growth of six bermudagrass [Cynodon dactylon (L.) Pers.] selections from the Appalachian region. Midland, a cold tolerant bermudagrass, was included in the study for comparison purposes. The grasses were grown under a 14 hour day length with three day/night temperature regimes: 18°C/13°C, 27°C/21°C, and 35^OC/29°C. Two of the selections had significantly higher dry matter production than Midland over the range of temperatures.

This effect was especially pronounced at 35°C where the top growth of Quicksand common and Selection 13 exceeded that of Midland by 206% and 158%, respectively. The higher yielding selections were comparable to the other bermudagrasses when mineral concentrations, neutral detergent fiber, acid detergent fiber and acid detergent lignin levels were considered. Both Quicksand common and Selection 13 seem to have the potential to be particularily useful on south facing slopes where elevated soil temperatures are encountered.     

水稻雄性不育突变体012S-3的遗传分析和基因定位

雄性不育是水稻杂种优势利用的重要资源,对雄性不育现象的研究具有重要理论意义和实践价值。本研究以自然突变的水稻雄性不育突变体012S-3为试验材料,对其表型特征和花粉育性等进行调查,并构建遗传群体,利用分子标记对目的基因进行初步定位,然后应用基因组重测序技术对其进行精细定位。结果表明,012S-3是一个典型的无花粉普通型雄性不育材料,其不育性状受1对隐性核基因控制。初步定位分析目的基因与SSR标记RM6081存在连锁关系,其遗传距离约为34.4 c M;进一步的精细定位分析,找到3个候选基因:LOC_Os07g35880、LOC_Os07g35920和LOC_Os07g35940,其中LOC_Os07g35880和LOC_Os07g35940编码β-淀粉酶,属于水稻中新发现的花粉致死基因。该不育基因的成功定位为其进一步的分离克隆及其在水稻分子设计育种中的应用奠定了基础。     

关中灌区粮食生产“两高一优”机械化模式

根据关中灌区自然经济条件，提出了一种新的机械化模式。经过９年实践表明，采用该模式，无论丰年、平年、灾年均可大幅度增产，能提高抵抗自然灾害的能力，使丰、灾年间产量波幅减小，更趋稳定。     

几种中微量元素肥料对烤烟产量及品质的影响

2011年,在吉林省大安市、洮南市和镇赉县分别进行了大田烤烟,锰、硼、钼、锌和镁肥的施肥量和施用方法的试验研究。试验结果表明:在锰、硼、钼、锌和镁等中微量元素有效含量缺乏的烟田中,增施适量的中微肥,能够促进烤烟的营养均衡并在此基础上促进其生长;能够提高土壤和叶片中相应的中微量元素含量;烤烟的经济效益也随之得到提高。从试验长势看,所有试验中微肥都比对照好,喷施比基施表现要好,基施中硼、钼、锌、镁表现比较好,喷施中硼、钼、镁、钾+钼、钾+锌表现最好;从烘烤质量上看,不论基施的还是喷施的钼都表现得最好。     

东塘水蜜桃高产优质栽培技术

通过对东塘水蜜桃生物学性状进行观察,总结其高产优质栽培技术:规划建园,科学种植;合理整枝修剪,培养良好树冠;科学施肥,提高品质;科学防治病虫害。     

耕作与施肥模式对渭北旱塬春玉米田蓄水保墒与玉米产量的影响

为揭示渭北旱塬春玉米田休闲期不同保护性耕作模式的蓄水保墒与增产增收效应,寻找适合渭北旱塬春玉米田水肥高效利用的耕作方式和施肥水平,于2013—2014年度在陕西省合阳县甘井镇春玉米田分别设置传统农户模式(翻耕+低肥,S1)、现有高效模式(免耕+高肥,S2)、创新高效模式(深松+平衡施肥,S3)等模式处理,研究各类耕作与施肥相结合保护性耕作模式下春玉米水分利用率、产量和经济效益差异。结果表明,创新模式S3和现有模式S2较农户模式S1播前增加了土壤贮水量;创新模式S3和现有模式S2处理在玉米主要生育期0~200 cm土层平均土壤贮水量分别比农户模式S1增加23.3 mm和18.1 mm,水分利用效率分别提高12.3%和10%,产量增加11.1%、9.2%。创新模式和现有模式均较农户模式能够增加土壤贮水量,提高水分利用效率,增加产量和经济效益,但创新模式蓄水保墒,增产增收优势明显,是适合渭北旱塬地区春玉米生产的水肥管理模式。     

涝害对甜叶菊光合及单株干叶产量的影响

利用温室盆栽法研究不同持续时间涝害对甜叶菊种质材料IS-1、QF-1、青甜杂4、JD-1、AL-4光合作用及干叶产量的影响。结果表明：随着涝害时间的持续,5份甜叶菊种质材料的叶绿素SPAD值、净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）及单株干叶产量均表现出不同程度的变化。短时间涝害处理（Ta：5d）对SPAD值、Pn、Gs、Ci、Tr及单株干叶产量影响均不显著;但随着渍水时间的持续叶片SPAD值、Pn表现出下降趋势：在Tb（涝害处理10d）中IS-1、QF-1、青甜杂4、JD-1、AL-4的SPAD值较正常水分处理分别下降21.29%、34.57%、27.84%、23.01%、17.59%,QF-1下降最快,AL-4下降最慢;Pn较正常水分处理分别下降65.88%、78.51%、74.44%、71.68%、59.58%,QF-1下降最快,AL-4下降最慢;Gs与Tr变化趋势与Pn相似,而Ci与Pn变化趋势相反;随着涝害持续时间的持续,甜叶菊单株干叶产量出现下降趋势,不同材料相同时间涝害胁迫单株干叶产量下降幅度不同,表明不同材料对涝害的耐受力不同。