Late Holocene paleopedological records contained in tephra from El Chichón volcano, Chiapas, Mexico

High rates of pedogenesis on unconsolidated volcanic materials imply the accelerated generation of the soil memory. The purpose of this research was to extract the high resolution (centennial scale) paleopedological records from the Late Holocene paleosols of the El Chichón volcano formed during the last 2000 years. We studied buried monogenetic Andosols on the dated tephras and a pedocomplex formed from a set of thin ash layers deposited on older Acrisol derived from shales. Particle size distribution, DCB-extractable Fe, oxalate-extractable Fe, Al and Si, sand and clay mineralogy, organic carbon content and stable C isotope composition in humus were evaluated and interpreted as the elements of the soil memory. However, some differences were found in properties of two buried soils, especially in the kind of A horizons. We attribute such differences of individual Andosols to be caused by ancient human impact because it has been demonstrated that humid conditions persisted during the last 1300 years. Thus the drought that was supposed to provoke the collapse of the Maya civilization at the end of I millennium A.D., should have been a short-term event, below the resolution of this paleopedological record. The Andic Acrisol pedocomplex demonstrated the domination of the humid tropical climate over longer time intervals (probably major part of the Holocene) with possible minor dry episodes.     

Performance of Dimethomorph + Mancozeb Applied to Seed Potatoes in Early Management of Late Blight (<Emphasis Type="Italic">Phytophthora infestans</Emphasis>)

Treating seed potatoes with contact fungicides prevents infection of Phytophthora infestans from tuber to tuber during handling but does not prevent field infections in the young plant. Dimethomorph (DMM) 9% + mancozeb 60% (Acrobat MZ, BASF) can cover both aspects due to the contact and systemic action of mancozeb and DMM, respectively. Experiments were performed under greenhouse and field conditions (three seasons and two locations) with cvs Kennebec, Shepody, Spunta, Russet Burbank, and Ranger Russet. Immediately after cutting, seed pieces were treated with Acrobat MZ at doses equivalent to 2, 3, and 4 kg ha⁻¹. At any dose, Acrobat MZ protected healthy seed tubers against P. infestans infections. Acrobat MZ (4 kg ha⁻¹) also protected the foliage of all cultivars against artificial inoculation of P. infestans, assessed by the detached-leaf method. These effects were observed up to 30 days after emergence in greenhouse experiments and up to 28 days after crop emergence under field conditions in two growing seasons. In cv Spunta, significant foliage protection was observed up to 35 days after field emergence whereas in seed tubers of cv Kennebec planted in sandy soils, significant foliage protection persisted longer. Additional evidence for acropetal translocation of Acrobat MZ in field crops was also found. With this strategy, there is no need to apply contact or systemic fungicides early in the season, and spraying costs and environmental risks are also reduced.     

长江中下游麦区小麦迟播的不利影响及育种对策

近年来长江中下游稻麦轮作区水稻成熟期不断推迟,致使小麦播期大幅度推迟,这已成为该麦区小麦高产稳产的主要障碍。迟播不仅导致小麦生育期缩短,积温、光照时数减少,营养生长不足,难以形成高产群体基础,还导致赤霉病和白粉病严重发生,增加了灌浆期遭遇高温危害的风险及收获前遇阴雨发生穗发芽的概率。为了减少小麦迟播的不利影响,除了栽培措施应对外,根本措施是培育适合迟播的小麦品种。在育种时应重点加强迟播条件下出苗快、生根快、分蘖早、越冬期仍能保持较大生长量和分蘖发生量等性状的选择;提高抗性,特别是赤霉病抗性、耐渍性和抗穗发芽性;注重选择灌浆速率高、耐高温逼熟的品种,利用灌浆速率的提高补偿灌浆时间缩短的不利效应,培育迟播高产品种。     

干奶牛阴离子盐利用效果研究初报

选用干奶后期奶牛10头,探讨干奶期奶牛应用阴离子盐产生效应所需的条件。结果表明:1、收穗后青刈玉米秸与小麦秸作为大容积性饲料,尿液pH易达到阴离子盐产生效应的状态,而萨拉秧与苜蓿干草则不易达到;2、不同大容积性饲料,阴离子盐的适宜添加量不同,收穗后青刈玉米秸、苜蓿干草的适宜添加量为每头440～500g/d,小麦秸则为440g/d;3、将添加的阴离子盐分成两部分,一部分与精料均匀混合,另一部分先溶于少量水,再均匀喷洒于大容积性饲料表面进行饲喂,可避免阴离子盐对采食量的影响。     

晚粳新品种宣鉴90-1的选育与栽培要点

晚粳新品种宣鉴９０—１，一般单产６０００ｋｇ／ｈｍ２左右，高产田块单产达７５００ｋｇ／ｈｍ２。比鄂宜１０５增产６．９％～７．６％。抗稻瘟病，中抗白叶枯病。米质优良，适宜在我省双季稻地区种植     

新质源籼型杂交晚稻“东优13”的选育

介绍了新质源籼型杂交晚稻“东优13”的选育经过、主要特征特性、栽培及制种技术要点。     

太湖地区晚粳地方种稻米RVA谱特征多样性分析

利用50年代征集的368份太湖地区晚粳稻地方种资源材料（部分种质资源名见表1），系统测定与分析了其稻米RVA谱特征并对其多样性进行了测算。结果表明，这些种质资源的稻米RVA谱曲线特征分化明显，种质间差异极显著，呈现从籼性到糯性连续变化的特征，形成4种特征类群（见图2）。绝大多数种质（约51.9%）RVA谱的消减值在300~1 000 cP，属于典型的粳稻品种，为A类型；少量种质（如大红稻、早日黄稻、上海青、苏州青、慢红谷等）具有糯性淀粉RVA谱特征，为C类型；一些种质（如金谷黄、慢白稻、粗营洋晚稻、细叠谷、立更青）表现典型的籼稻淀粉RVA谱特征（D类型）；部分种质具有优质的RVA谱特征，即消减为负值（如天下第一种、大青种、黄谷大稻头、摇矮子、余山种等），表明种质的淀粉性质存在明显的差异。各特征值的表型遗传多样性指数均大于1，其中崩解值的遗传多样性指数达2.04。RVA谱各特征值间显著相关，并可用崩解值、消减值2个指标来简化定量描述稻米RVA谱的特征。     

早熟高产多抗冬小麦新品种 晋麦74号生育特性及配套栽培技术

为了给早熟高产多抗小麦新品种晋麦74号的推广应用提供配套的高产栽培技术,对其生育特性进行了初步研究。结果表明,晋麦74号具有前中期发育快,分蘖早而强,成穗率高形成较多的穗数;穗分化开始早,进程快,抽穗早形成早熟的特点。中后期幼穗发育与籽粒灌浆均较快,其灌浆期长短与对照品种相同,能避开干热风,粒重高而稳定。该品种具有多穗性强的特性,使其具备了播种期范围广和适应性强的栽培特点。     

冬小麦生长后期地上部分氮素的氨挥发损失

在拔节到成熟期，采用密闭生长室法直接收集和测定了种植在高、低两种肥力土壤上的冬小麦挥发的氨气。结果表明，进入成熟期后施肥处理的冬小麦地上部分的氨挥发速率和数量成倍升高，而不施肥的处理和生育前期相比无明显变化。同一植株不同部位的挥发量相差很大，下部衰老茎叶的氨挥发量明显高于生长正常的上部穗和旗叶。灌浆     

优质晚熟耐贮白肉桃新品种--艳丰一号

‘艳丰一号’桃是自然实生新品种，树势强健，平均单果质量250g,果面1／2以上着红色晕，肉质白色，肉脆而甘甜，9月上中旬成熟，耐贮藏，早果丰产，适应性强，6年生树年产量可达37.5t/hm^2。