我国高校贷款的现状、问题及对策研究

本文从高校、银行、政府三方面全面地分析了高校贷款的现状及高校贷款问题的成因, 并提出对策和建议。笔者认为, 由于高等教育的准公共性, 单由高校一方或政府一方还贷都是缺乏合理性的, 除了要采取加大财政投入力度、严格贷款审批程序、完善教育经费投入机制、扩充高校经费来源渠道等措施外, 笔者建议建立高校和政府合理分担的还款机制来解决我国目前存在的高校贷款问题, 旨在为高校贷款问题的解决提供一点思路。     

氮素形态对烤烟成熟过程中抗坏血酸-谷胱甘肽循环的影响

探讨了氮素形态对烤烟成熟过程中抗坏血酸-谷胱甘肽循环系统的影响。结果表明,烟叶自移栽后60 d开始,抗坏血酸过氧化物酶(APX)活性和抗坏血酸(ASA)含量逐渐上升,到70~80 d达到最高峰,随后稳定在一定的水平。3种不同氮素形态处理的APX活性和ASA含量变化规律相似,均随着硝态氮比例的增加而增大;谷胱甘肽还原酶(GR)活性在移栽后90 d达最大值,此后逐渐下降,谷胱甘肽(GSH)含量随着烟叶的成熟持续下降。烟叶成熟过程中各处理GR活性和GSH含量随着铵态氮比例的增加而增大。     

油菜籽含油量与气象因子的相关及预报模式

近年来,长江下游亚区菜籽含油量的变异范围处34.～44.9％,集中在39.0～40.9％.年度间差异3～5％左右.本区内相同品种的地域差异为纬度每增高一度,含油量增加0.4439％.种子形成期光强减弱至自然光强的1/4,含油量比对照降低16.63％;温度与水分差异亦可使含油量降优5～7％.种子形成期是气象因子影响含油量的关键时期,含油量与此期的降水量呈负相关,与日平均温度、≥3℃有效积温、日照时数呈正相关.因此,可用种子形成期的日照时数为主要气象指际,抽苔期日平均温度为辅助指标,在此基础上初步建立含油量预报的数学模型.     

榨菜瘤状茎形成及其与花芽分化的关系

采用播种期试验与光照处理相结合的方法，研究了榨菜（ＢｒａｓｓｉｃａｊｕｎｃｅａＣｏｓｓ．ｖａｒ．ｔｕ－ｍｉｄａＴｓｅｎｅｔＬｅｅ）瘤状茎的形成及其与花芽分化的关系。结果表明，影响瘤状茎形成的主要生态因子是温度和光照。在杭州（北纬３０°）地区，春季适合瘤状茎形成的５天平均温度为７．７—１７．７℃，日照长度从１１．Ｏ小时延长至１２．７小时；秋季适合瘤状茎形成的５天平均温度为２２．５—５．７℃，日照长度从１２．７小时缩短至１０．３小时。在适合榨菜瘤状茎形成的生长时期给予连续光照，则能抑制瘤状茎的形成，在杭州地区，无论是长日照或短日照，在旬平均５．４—２６．３℃条件下，榨菜一年四季都会进行花芽分化。４月中、下旬播种的，从播种至花芽分化的时间最短，仅３６—４１天。花芽分化的旬平均温度为１９．９℃，日照为１３．７小时，长日照具有促进花芽分化的作用，１０月上中旬为榨菜生产上的主要播种季节，花芽分化和瘤状茎形成均在翌春，榨菜瘤状茎充分膨大，三层瘤状物明显突起，花芽分化至始蕾期，标志瘤状茎成熟。榨菜的部分营养生长期与部分生殖生长期交错重叠。     

Determining soil water‐balance components using an irrigated grass lysimeter in NE Austria

The water balance of a certain soil profile in a certain time interval is subjected to changes of soil water content within the respective profile, and fluxes at its upper and lower boundary. Weighing lysimeters are valuable instruments for water‐balance studies. Typically, mass changes—thus, changes of soil profile water content—are detected by a weighing system, while seepage water outflow is measured by a tipping bucket, and precipitation data originate from a rain gauge. Hence, evapotranspiration as unknown component can be determined by solving a simple water‐balance equation. However, using separately measured precipitation data may cause implausible (negative) evapotranspiration. In this study, change of soil profile water content, seepage water, precipitation, and evapotranspiration were determined directly from 10‐min lysimeter data from 2011. Precipitation measured with the lysimeter was in total 20% greater than rain‐gauge values. Even dew formation was measured and considered as water‐balance component; however, its total amount was rather low. Evapotranspiration calculated on daily and hourly base indicated a sound correlation with measured data, but measured values were considerably smaller. Both calculated and measured dew amount were of the same magnitude. Comparison of lysimeter evapotranspiration with daily calculations (neglecting dew) and hourly computation (considering dew) delivered similar results. Generally, the utilized lysimeter facility and the specific data management provided sound water‐balance components with high accuracy and temporal resolution, respectively.     

双季晚粳稻氮肥精确运筹研究

【目的】我国南方双季稻区晚稻品种以籼稻为主。近年来我国粳米需求量逐渐增大,研究者提出了利用南方双季稻区充足的温光等资源进行晚季稻籼改粳以提高粳稻总产量。系统研究双季晚粳稻高产、优质和高效的氮肥运筹方式就显得十分重要。【方法】 2011~2012年,在南方典型双季稻区江西省上高县泗溪镇,以杂交粳稻常优5号和甬优8号为晚稻材料,在总施纯氮量 225 kg/hm2 条件下,设置10∶0、8∶2、7∶3、6∶4、5∶5、4∶6、3∶7 七种基蘖肥与穗肥运筹比例,通过研究不同氮肥运筹方式对双季晚粳稻产量及其构成因素、叶面积指数、茎蘖动态、光合物质生产与积累、氮 素吸收利用以及稻米品质等方面的影响,明确了南方稻区双季晚粳稻氮肥精确运筹模式。【结果】 随基蘖肥占总施氮量比例的降低,结实率、千粒重和每穗粒数呈先增加后减少的趋势,穗数呈减少趋势。氮肥基蘖肥与穗肥比例在6∶4、7∶3范围内,双季晚粳稻群体穗数充足、穗型大、群体颖花量高,且结实率和千粒重较稳定,产量显著高于其他处理,最高产量为9985 kg/hm2。拔节前群体茎蘖数增加较慢,但高峰苗数适宜,拔节后群体茎蘖数下降平缓,茎蘖成穗率显著高于其他处理,高于70%;生育中期和后期,群体叶面积指数较高,群体光合势高,光合生产力强,干物质积累量显著提高。随基蘖肥占总施氮量比例降低,成熟期氮素积累总量、氮肥表观利用率、氮肥农学利用率及氮肥偏生产力均呈先增加后减少的趋势,百公斤稻谷需氮量呈先减少后增加的趋势。6∶4和7∶3处理拔节前氮素积累量较少,拔节至抽穗期氮素积累量和成熟期积累量显著高于其他处理。6∶4和7∶3处理氮肥表观利用率、农学利用率及偏生产力显著高于其他处理,百公斤稻谷需氮量显著低于其他处理。氮肥表观利用率 与基蘖肥比例呈开口向下的二次曲线关系。同时该氮肥运筹模式可改善稻米加工品质、蒸煮食味和营养品质,但增加了稻米垩白率和垩白度,RVA谱特征值各指标不能同时达到最佳值。【结论】基蘖肥∶ 穗肥为 6∶4、7∶3的氮肥运筹方案,可使双季晚粳稻高产、优质、高效得到较好的协调统一。     

钾营养对杂交稻光合作用动态及产量形成的效应

 用杂交稻威优35号在低钾土壤上进行盆栽试验，设置三个钾水平：K0(不施钾)；K1(1．5 g K/ 15 kg土)；K2(3．0 g K／15 kg土)。结果表明：(1) K0处理叶片发育过程中净光合率降低而暗呼吸增高，叶绿体发育迟缓而解体较早，光合功能期缩短；K1及K2的净光合率明显高于K0，光合功能期亦较长，而暗呼吸则长时期保持较低水平。(2)K0处理在灌浆期净光合作用有明显的“午休”现象， 而K1、K2则在夏日中午仍保持较稳定的净光合率。(3) K0处理“午休”的出现与蒸腾速率增高有关，且在上午9时还有一蒸腾高峰，使叶子大量失水；施钾处理在一天中的蒸腾曲线则较平稳。(4)K0处理稻株叶片中含K量从上到下有明显梯度，灌浆期下层叶的含K量仅为剑叶的30．08％，易引起早衰，且使根系生长受到严重影响；施K处理叶片从上到下无明显梯度。总之，施K增加光合面积，避免早衰，增加粒数，显著提高谷粒产量。     

小麦与玉米远缘杂交诱导小麦单倍体的研究

为了研究在小麦×玉米中亲本及2,4-D对诱导小麦单倍体的影响,将36个小麦杂交组合的F1植株与4个玉米品种分别进行远缘杂交,杂交后用50、100、150mg·L-1三种不同浓度的2,4-D溶液处理杂交穗,结果表明,不同小麦杂交组合远缘杂交的得胚率差异显著;不同玉米品种远缘杂交的得胚率总趋势表现为:爆烈玉米(9.9%)>糯玉米(8.9%)>普通玉米(8.2%)>甜玉米(4.6%);2,4-D对小麦单倍体的形成是必须的,且不同浓度之间存在差异,以100mg·L-1浓度处理效果最为理想;同时,2,4-D重复处理的得胚率高于一次处理。     

The expression of general resistance to late blight (Phytophthora infestans) in potato leaves

Summary Resistance toPhytophthora infestans was evaluated histologically using leaves of potato cultivars with different levels of general resistance. Host genotype did not influence the preinfectional processes of encysted zoospores, e.g. frequency of germination, length of germ tubes, or frequency of formation of appressoria. Most of the appressoria on the leaf surface were attached to epidermal cells, but they were also found on cells of the stomatal complexes, on hairs and glands, and on cells adjacent to vascular tissue. There were significant differences between cultivars in the extension of intercellular hyphal growth and branching 24 and 48 h after inoculation, the differences increasing with time. In contrast to cv. Bintje, the hyphae in the most resistant cultivar Matilda were mostly confined to the epidermal and palisade cells even 48 h after infection, the number of hyphae per section was much lower, and sporulation capacity was reduced.     

The effect of genotype and culture medium on somatic embryogenesis and plant regeneration from mature embryos of fourteen apomictic cultivars of buffel grass (Cenchrus ciliaris L.)

Buffel grass (Cenchrus ciliaris L.) is an important apomictic grass used as forage for ruminant livestock. Biotechnological methods provide opportunities for producing new germplasm. Mature embryos of fourteen buffel grass apomictic cultivars (2n = 4x = 36) were used to induce embryogenic callus formation using a basal medium supplemented with 3% sucrose and with the testing of five concentrations of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and four concentrations of 6‐benzylaminopurine (BAP). The effects of cultivar and culture medium on callus induction and plant regeneration were evaluated. Significant differences were observed among the fourteen cultivars and the five concentrations of 2,4‐D (P < 0·01). Values for embryogenic callus production varied from 0 to 86·7. Most cultivars showed the highest level of embryogenic callus production on the medium with the concentration of 3 mg L^?1 2,4‐D. The addition of different BAP concentrations in combination with 2,4‐D in the medium inhibited embryogenic callus growth and did not permit plant regeneration. The data clearly demonstrated that the genotype and concentrations of 2,4‐D had significant effects both on the frequency of embryonic callus formation from mature embryos and on the subsequent efficiency of plant regeneration of apomictic cultivars of buffel grass. Cultivars Biloela and Nunbank showed the greatest efficiency in in vitro culture response.