磷素对甘薯生长前期源库关系建立和平衡的影响

通过2年盆栽试验研究不施磷P₀（P₂O₅ 0 g/kg）、适量施磷P_0.04（P₂O₅ 0.04 g/kg）和过量施磷P_0.08（P₂O₅ 0.08 g/kg）对鲜食型甘薯‘烟薯25’和‘普薯32’生长前期（栽后0~40 d）根系活力、根系形态分化、潜在块根重量、结薯数、薯块重量、根生物量、叶面积、茎叶生物量、根干物质分配比例、茎叶干物质分配比例及根冠比的影响。结果表明,在块根形成期（栽后0~30 d）,与不施磷处理相比,适量施磷显著提高了甘薯总根条数、根尖数、总根长、根系表面积、根系平均直径、根系体积和总根鲜重,并显著提高了根系活力,提高了潜在块根鲜重;显著提高叶面积、叶鲜重、茎鲜重、地上部总鲜重;显著提高甘薯茎叶干重、根干重和植株干重,显著增加干物质根分配比例,降低干物质茎叶分配比,显著提高根冠比,为块根形成提供良好的物质基础。而过量施磷抑制干物质在根中的分配比例,导致根冠比降低,不利于块根的形成。在封垄期（栽后40 d）,与不施磷处理相比,适量施磷可以显著增加单株结薯数（主要提高直径5 mm以上的块根数量）、单薯重和单株薯重,若继续增加施磷量将导致单株结薯数和单薯重显著降低。因此,适量施磷可以促进甘薯根系和茎叶发育,增加干物质根分配比例,降低干物质茎叶分配比,显著提高根冠比,增加甘薯单株结薯数和单薯重,提高单株薯重,促进甘薯生长前期源库关系建立和平衡,为甘薯丰产奠定基础。     

从重庆市甘薯生产现状谈推广高淀粉品种

在测定和调查了重庆市农业生产上应用的１１个甘薯品种的干物质含量,淀粉含量和生产力的基础上,初步提出了目前重庆市的甘薯推广新品种为：兼用型品种渝薯３４和南薯８８,淀粉加工专用型品种徐薯１８,渝苏１号,苏薯２号和绵粉１号,重庆市甘薯生产的出中在于加工,在推广高淀粉品种的前提下,走农户或就地小规模初级加工淀粉,企业收购淀粉进行各类深度加工的道路。     

施钾量对淀粉型甘薯徐薯26产量形成及钾利用的影响

以淀粉型甘薯徐薯26为试验材料,研究了不同钾肥施用量对干物质积累与分配、光合特性、产量、块根淀粉含量及钾肥利用率等的影响。结果表明,适量施钾可提高块根膨大速率,有利于同化物向地下运输,降低T/R值,提高叶片光合速率,提高鲜薯产量和淀粉产量。因此,在土壤钾含量为78 mg/kg的试验条件下,综合考虑鲜薯产量、淀粉产量和钾肥利用率等指标,淀粉型甘薯徐薯26的最佳施钾量为K2O 375 kg/hm2。     

丘陵旱地甘薯豫薯8号的生长分析

采用植物生长分析法，对丘陵旱地甘薯豫薯8号进行物质生产性能分析，结果表明：豫薯8号的叶面积系数（LAI），相对生长率（RGR）和净同化率（NAR）均显著高于徐薯18，在整个生长过程中，豫薯8号的NAR有两个高峰期，分别为栽后的50－70d和90－100d；第一个高峰期其NAR为6．24g/(m2./d)，比徐薯18提高20．2％，第二个高峰期NAR为6．56g/(m2.d)，比笔薯18提高13．5％，豫薯8号的叶面积比率（LAR）则略低于徐薯18，证明茅薯8号有良好的物质生产性能，可作为徐薯18的理想换代品种。     

甘薯块根发育过程中关键蔗糖分解酶及其基因家族成员的鉴定

蔗糖分解酶在马铃薯和胡萝卜等块根/块茎的生长发育中发挥着重要作用,但在甘薯块根发育中的作用机制尚不清楚。本研究以2个在块根数量和鲜重上存在显著差异的甘薯品种‘高系14'及其突变体为材料,对其不同发育时期（30、60、90、120 d）块根中的可溶性糖（蔗糖、葡萄糖和果糖）、淀粉含量、蔗糖分解酶活性以及相关基因家族成员的表达水平进行测定,以明确调控块根数量和大小的关键蔗糖分解酶及主要基因家族成员。结果表明：（1）阐明了4种蔗糖分解酶活性在薯块根发育过程中的变化规律,细胞质转化酶（CIN）和液泡转化酶（VIN）活性的整体变化趋势呈现‘u'形曲线,即块根发育早期、晚期活性相对较高,发育中期最低;细胞壁转化酶（CWIN）和蔗糖合成酶（Sus）活性整体变化趋势呈‘n'形曲线,与前者正好相反,即在块根发育早期、晚期较低,发育中期最高。（2）和突变体相比,具有较高块根数量和鲜重的‘高系14'在块根发育早期（30 d）具有较高的Sus和CIN活性,而高Sus和CIN活性可以促进蔗糖由叶片向块根转运,从而提高块根中的淀粉、蔗糖和葡萄糖含量,最终为块根的生长发育提供能量和碳骨架以增加块根数量和鲜重。（3）从甘薯基因组中共鉴定出9个Sus基因家族成员和12个CIN基因家族成员,其中有1个Sus基因（IbSus6）和5个CIN基因（IbCIN4、IbCIN6、IbCIN8、IbCIN10和IbCIN11）的表达水平在30 d时表现为‘高系14'显著高于突变体,同时IbSus6和IbCIN4、IbCIN8、IbCIN10、IbCIN11分别为30 d块根中表达的主要Sus和CIN基因家族成员,因此上述1个Sus基因家族成员和4个CIN基因家族成员可能是调控甘薯块根发育的主要蔗糖分解酶基因。总之,Sus和CIN在甘薯块根早期发育中发挥着重要作用,其关键基因家族成员的阐明可为优异甘薯新品种的选育提供理论依据。     

高产优质兼用型甘薯品种豫薯八号

高产优质兼用型甘薯品种豫薯八号王宜钦王自力（河南省洛阳市农业科学研究所洛阳４７１０２３）豫薯八号是洛阳市农业科学研究所１９８７年以蓬尾为母本，以小白藤为父本，通过有性杂交选育的兼用型甘薯新品种。具有高产、高干率、高淀粉含量、食味好、高抗根腐病等突出特...     

紫肉甘薯新品种渝苏紫43的产量表现及主要经济性状

对紫肉甘薯新品种渝苏紫43的生产力和主要经济性状的鉴定结果进行介绍。分别于2007—2008年参加重庆市甘薯品种区域试验和生产试验,并对渝苏紫43鲜薯产量、藤叶产量、薯干产量、淀粉产量、薯块干物率、淀粉含量进行测定;2008年经江苏省农业科学院食品质量安全与检测研究所测定鲜薯薯块总花色苷含量,薯块萌芽性好,上薯率85%以上。该品种可作色素、淀粉、保健综合利用型甘薯品种。     

烟薯20号加工利用价值分析及高产栽培技术研究

烟薯20号是一个薯形较好,肉色深黄,高干的适合出口加工的新品种.目前市场上的高系14、红东等品种老化,产量低,因此选育高干,肉色深黄,品质优良的甘薯新品种成为甘薯育种的一个新目标.     

甘薯新品种商薯6号

甘薯新品种商薯6号是利用其亲本绵粉1号中产、高干、食味好的特性,为使其提高鲜产,保持其亲本优异特性,2002年将绵粉1号授粉获得杂交种子,2003年进行实生苗选择,从其后代中选育出了符合国家淀粉型鉴定标准的甘薯新品系商025—6。2009年3月通过国家甘薯鉴定委员会鉴定。鉴定编号：国品鉴甘薯200905,并定名为商薯6号。     

甘薯南薯88干物质积累与分配规律研究

以徐薯18为对照,对南薯88的干物质积累与分配规律进行研究。结果表明,南薯88干物质的积累在整个生育期内高于徐薯18,其分配规律为前期以地上部茎叶生长为主,中期地下部块根逐渐增加,后期则以地下部积累为主,源库关系协调,具有较高的生物产量、经济产量、净同化率和经济系数。     

氮肥运筹对不同生育期晚稻品种产量及氮素吸收利用的影响

以6个生育期不同的晚稻品种为材料,研究了不同生育期品种对不同氮肥运筹比例的响应。结果表明,早熟品种在基蘖肥∶穗肥为7∶3时的产量高于6∶4时的产量,而中、迟熟品种中既有在7∶3时表现为产量较高的品种,也有在6∶4时表现为产量较高的品种。而不同氮肥运筹比例对不同生育期晚稻品种间的氮素吸收利用的影响与品种熟期之间没有明显的规律性。     

深松耕法对甜菜增产效果的研究

试验表明,深松耕法不仅能改善土壤的物理性状,创造合理的土壤耕层,而且促进了植株的生长发育。研究看出,土地深松后的甜菜生育期内叶面积指数增加了0.05～0.31;干物质积累强度增加了0.465g/(株·d);叶面积指数达3以上的净同化率增加0.34～0.73g/(m~2·d)。3年平均根增产15.5％,含糖率增加1.73度,产糖量增加27.6％。     

高产抗病圭亚那柱花草综合性状评价

1998年引进14个柱花草种质品种,以中国热带农业科学院选育的热研2号柱花草和热研5号柱花草为对照进行比较试验。结果表明:GC1480(IRRI)、GC1463(IRRI)和GC1517(IRRI)柱花草的干物质产量达11 377.5、9 360.2、9 296.7 kg/(hm2·a),分别比热研2号的高26.49％、4.06％和3.35％,比热研5号的高72.24％、41.70％和40.74％;且GC1480(IRRI)、GC1463(IRRI)柱花草的旱季干物质产量较高,具有较强的抗旱性;抗柱花草炭疽病能力优于热研5号柱花草;在定期刈割条件下,植株存活率分别达77.50％、50.00％和49.17％,具有较强的抗寒性;灰色关联分析评价结果表明,综合性状优于热研2号柱花草和热研5号柱花草。     

Partitioning of dry matter and nitrogen to the spike throughout the spike growth period in wheat crops subjected to nitrogen deficiency

Experiments were conducted over four seasons, in the field, with five cultivars. Nitrogen (N) fertilizer was applied to crops at various dates and rates to achieve various N deficiencies. Crop N status and the accumulation of dry matter (DM) and N in the vegetative parts and in the spike was assessed regularly throughout the spike growth period. Changes in partitioning during the spike growth period were studied using cv. Soissons. For crops subjected to continuous N deficiencies starting on various dates, the proportion of aerial DM in the spike was lower and the proportion of aerial N in the spike was higher than in well-fertilized crops. The earlier the deficiency, the larger were the differences in partitioning. Some crops were subjected to temporary nitrogen deficiencies. In these cases, a nitrogen deficiency starting on a particular date was brought to an end by applying N fertilizer. Crops exposed to temporary N deficiencies displayed a higher proportion of aerial DM and a lower proportion of aerial N in the spike than did crops subjected to continuous deficiencies. Differences in DM and N partitioning became significant at the beginning of the spike growth period if crop N status had been affected by deficiency as early as 800 or 700 degree days before anthesis. At anthesis, the relative proportion of aerial N in the spike (proportion of aerial N in the spike of a crop divided by the proportion of aerial N in the spike of its well-fertilized control) was linearly related to nitrogen nutrition index (NNI), an indicator of crop N status. This relationship was determined for Soissons and four other cultivars. It did not differ significantly between cultivars or between crops subjected to temporary or continuous deficiency. Relative aerial N content and relative spike N content were also related to NNI at anthesis.     

Storage of small bale silage and haylage – influence of storage period on fermentation variables and microbial composition

An experiment investigating changes in fermentation variables and microbial composition during storage of small‐bale silage and haylage was performed. Haylage was defined as silage with a dry‐matter (DM) content exceeding 500 g kg^?1. Grass was wilted to three different DM contents, and baled into silage (350 g DM kg^?1), haylage with a low DM content (550 g kg^?1) and haylage with high DM content (700 g kg^?1) in small rectangular‐shaped bales (0·80 m × 0·48 m × 0·36 m) that were individually wrapped. Bales were stored for short (2 months) or long (14 months) periods before opening and sampling. Silage had higher concentrations of fermentation products and a lower pH than either of the two haylage types. In general, long‐term storage influenced all fermentation variables except concentrations of butyric acid and succinic acid, and yeast counts were higher after 14 months than 2 months of storage. However, silage changed in more fermentation variables during storage than the two haylage types. Although differences between short‐ and long‐term stored silage were found, linear correlations between short‐ and long‐term stored bales were present for all chemical variables. Pearson's correlation coefficients were highest for lactic acid, followed by pH.     

Potential of Cistus ladanifer L. (rockrose) in small ruminant diets – effect of season and plant age on chemical composition,in vitro digestibility and antioxidant activity

Shrubs can provide an important contribution to the fodder resources for small ruminants in Mediterranean areas, but there is limited information on their feed value, including secondary metabolites and their seasonal differences. This study evaluated the effect of seasonal variation in chemical composition, in vitro digestibility and antioxidant activity of the aerial parts of plants of Cistus ladanifer of two age groups [young plants vs. older ones (2–6 years old)]. Aerial parts of C. ladanifer plants of both age groups were characterized by moderate cell‐wall content [321–410 g NDF kg^?1 dry matter (DM)], high levels of phenolic compounds (55·1–106 g gallic acid equivalents per kg DM) and condensed tannins (CT) (32·1–161 g kg^?1 DM), low protein content (55–100 g kg^?1 DM) and low digestibility (249–315 g of digestible organic matter per kg DM). During autumn and winter, C. ladanifer showed higher protein levels and lower cell‐wall content than in the other seasons. The highest values of phenolic compounds, CT and antioxidant activity were achieved during summer. Young plants showed higher levels of phenolic compounds during spring, summer and winter, and higher CT contents in summer (more than 54 g kg^?1 DM) compared to old plants. Aerial parts of C. ladanifer of both age groups may be used as a component of ruminant nutrition, but only as a supplement and associated with other feeding resources to complement its nutritional imbalances.     

Changes in photosynthesis,growth, and sugar content of commercial sugarcane cultivars and Erianthus under flood conditions

Sugarcane (Saccharum spp.) is an economical crop in the tropical and subtropical countries. However, because of global climate change, flooding has become problematic, particularly during the rainy season, in Thailand. We investigated the effects of floods on three commercial sugarcane cultivars, namely NiF8, U-thong 6 (UT6), and U-thong 9 (UT9), as well as Erianthus spp. Growth was assessed using a pot experiment in a glasshouse with two treatments: (1) control and (2) 60 d of flooding followed by 30 d of normal conditions. In comparison with control, during prolonged flooding, Erianthus showed greatly decreased CO₂ assimilation, whereas NiF8, UT6, and UT9 showed slightly declined CO₂ assimilation. Growth in plants subjected to 60 d of flooding was less influenced by floods while sucrose content was not affected except in UT6. During flooding, some roots died, resulting in plants compensating adventitious roots to offset the negative effects of root death and to assist them in maintaining their growth, which appeared from the submerged nodes, with different characteristics for each cultivar. However, 30 d after draining, roots remained damaged, while adventitious roots died, resulting in lesser growth as compared with the control, but it did not significantly affect sucrose content and sugar yield. This study suggests that sugarcane plants need to produce the adventitious roots to compensate their roots’ death during flooding and require time to recover their root system after flooding for obtaining the optimum yield and quality at harvest.     

Use of the in situ technique in the study of degradation of lucerne and smooth bromegrass genotypes

Six lucerne ( Medicago sativa ) genotypes (Beaver, Vernal and four other strains being developed at the University of Alberta) and five smooth bromegrass ( Bromus inermis ) genotypes (Carlton, Magna and three genotypes being developed) were examined in terms of forage dry matter (DM) yield and degradability, as determined by the rate and amount of material which disappeared from bags suspended in the rumen of cattle. Dry matter yield did not differ ( p > 0·05) between lucerne genotypes at first cut. The smooth bromegrass strain 517 had a proportionately Oil higher ( P < 0·05) DM yield than did the Magna strain. No differences ( P < 0·05) were detected within either smooth bromegrass or lucerne genotypes for 48 or 60 h in situ DM degradability. The 416E smooth bromegrass genotype, however, had a significantly higher ( P < 0·05) rate of DM degradation in the rumen than the other genotypes and also exhibited a longer ( P < 0·05) lag period before a significant amount of DM degradability occurred. In the in situ technique, approximately eighteen bags would have been needed to obtain DM degradability measurements with a confidence interval of 0·04 for DM degradability of a probability of 0·95. Further in vivo studies with the bromegrass genotypes are warranted to ascertain if the differences in digestion rates and lag times are related to meaningful differences in animal intake and digestibility.