灌溉条件下长期定位施肥对塿土剖面养分分布特征的影响

对塿土12年连续施肥后土壤剖面养分分布的研究发现,施肥使有机质、全P在耕层（0～20cm）与CK比较有不同程度的增加;施肥可以显著影响0～200cm土壤剖面有机质的含量;PK处理土壤剖面存在P素适度下移,120～220cm全磷含量呈现峰值;施肥对塿土耕层及0～300cm剖面全K含量几乎无影响;塿土粘化层可以减缓养分的下移;氮磷钾化肥与有机肥配合施用,使土壤NO3--N与CK比较有适度增加,对培育土壤肥力有利。     

驯化沙葱生长及其营养变化规律

通过沙葱驯化栽培试验,对其物候期及相关气候因子进行了连续2年观测,并对其营养成份进行对比化验.研究结果表明,驯化沙葱3月中下旬,气温大于2.35℃时,即开始萌动出苗;4月中旬,温度≥9.6℃,进入快速生长期.7、8、9月份气温≥22℃,降水较集中时完成开花结果;11月下旬,气温低于0℃时进入休眠期.沙葱刈割后,0～8 d高生长和粗生长最快,高生长平均达1.6 cm/d;10 d后,生长明显减弱;15 d后基本处于停滞状态;20 d后部分叶片丧失功能开始枯黄.驯化沙葱的营养成分同野生沙葱完全相同,但含量发生了变化.常量矿物质及微量元素和水分含量明显增加.各种氨基酸、粗蛋白、粗脂肪和β-胡萝卜素等含量有所下降,变异系数在9%～23%.沙葱与优质牧草苜蓿、多根葱相比,饲用品质优于两者.     

不同营养液配方对红葱生长及品质影响

研究4个营养液配方对红葱生长及营养品质的影响,结果发现:在水培条件下,从栽种开始前40d红葱生长主要是茎叶生长,40d~55d分蘖数急剧增加,茎叶生长量也继续增加;栽种前40d内配方T4较好,红葱产量较高,可溶性糖、可溶性蛋白、Vc含量高,硝酸盐含量最低。生产上可采用配方T4,并及时采收产品。     

玉米粒度对青年阉山羊生长性能及养分消化率的影响

将24只7月龄阉山羊(平均体重为17.53 kg)随机等分为3组,饲喂含细粉(平均粒度0.76 mm)、粗粉(平均粒度2.57 mm)及整粒玉米的全混日粮,3组日粮配方一致,日粮干物质中玉米含量均为28.35%。结果表明,玉米粒度不影响干物质采食量、生长性能以及日粮干物质、能量、粗蛋白、中性洗涤纤维和酸性洗涤纤维的全消化道表观消化率(P>0.05)。与细粉和粗粉玉米组相比,整粒玉米组降低了淀粉的全消化道表观消化率(P<0.05),趋于提高阉山羊的日增重(P=0.1396)。     

Bacteria-grazing amoebae in situ in the rhizosphere

Summary An ultrastructural investigation of amoebae in situ in the rhizosphere showed that the protozoa are closely associated with soil aggregates and produce long pseudopodia that penetrate micropores. This could partly explain why bacteria are generally confined to the interiors of microaggregates. The presence of cytologically intact and partly digested bacteria in the food vacuoles indicates that rhizosphere bacteria are both ingested and digested by the amoebae. This digestion could lead to the recycling of P and N immobilized in rhizosphere microorganisms.     

春玉米还原糖含量变化的研究

本试验对春玉米的叶片、叶鞘、茎秆和雌雄穗等器官的还原糖含量的变化进行了分层次的系统研究。结果表明,随着春玉米生长发育进程,各器官还原糖含量呈大幅度升降变化;拔节期和大喇叭口期叶片还原糖含量的两个峰值揭示了春玉米高产栽培需氮“前轻后重”的内在原因;生长中心器官的还原糖含量高,是器官迅速建成的生理基础;氮肥主要影响叶片的生长及生理代谢活性,进而影响叶鞘和茎秆建成,最终影响经济产量。在本地土壤条件下,产量的限制因素是“源”而不是“库”。     

同耐低磷基因型玉米磷营养特性研究

 采用盆栽试验系统研究了不同耐低磷特性的5个玉米自交系在生长过程中苗期、拔节期、孕穗期和吐丝期的磷营养特性。结果表明，在玉米苗期和拔节期，磷吸收效率是决定耐低磷特性的主要变异来源，低磷胁迫下，耐低磷自交系99180和99239植株相对吸磷量均显著高于敏感自交系99152。孕穗期，玉米自交系耐低磷特性主要体现在上部叶磷累积量较高，能保证玉米后期正常生长发育。吐丝期，耐低磷自交系99180和99239即使在低磷胁迫下，磷吸收效率和再分配效率仍明显高于敏感自交系99152。不同耐低磷自交系的磷营养特征也存在差异，99239主要表现为吸收效率较高，而99180则表现出更强的再分配能力。     

云雾山封育草地土壤养分变化特征

以云雾山封育23年的天然草地为对象,研究黄土高原半干旱区5种群落类型土壤养分的变异特征。结果表明:在自然恢复过程中,本氏针茅(Stipa bungeana)、百里香(Thymus mongolicus)、铁杆蒿(Artemisia veslita)、白颖苔草(Carex rigescens)和退化本氏针茅,土壤有机质含量、全量及速效氮磷钾含量均比对照区显著提高,其中恢复年限愈长,养分增加幅度愈大,其次序为:封育23年>封育12年>退化草地;同时,在0~100 cm土层中,土壤养分随着土层的加深呈逐渐降低的趋势。     

不同营养液浓度对莴苣生长特性的影响

 以长叶莴苣( Lactuca sativa var．1ongifolia Lam．)为试材，研究了NFT栽培条件下莴苣水分与养分吸收特性，以及NFT对其生长发育的影响。试验结果表明，莴苣蒸腾效率前期>中期>后期；整个生育过程中，P、K、Mg的吸收成分组成浓度(养分与水分吸收比，n/w)均低于原始营养液浓度，而Ca则相反；NO3^--N因处理浓度不同而异。叶片中各无机成分含量随生育过程而提高，同一生育期随营养液浓度提高而增加；综合莴苣产量因子与商品性状，以3/4倍园试均衡液最佳。     

Relationship of physicochemical characteristics and hydrolyzed hydroxycinnamic acid profile of barley varieties and nutrient availability in ruminants

The objectives of this study were to (1) investigate the relationship between physicochemical characteristics (mean/median particle sizes, physical hull content) and hydrolyzed hydroxycinnamic acid profile (ferulic acid (FA), para-coumaric acid (pCA), and their ratio) of barley varieties and in situ rumen degradability in dairy cattle; and (2) investigate rumen degradation kinetics of FA and pCA of CDC barley varieties grown in western Canada. Barley variety had a significant effect (P < 0.05) on rumen undegradable fraction of DM, FA, pCA, neutral (NDF) and acid detergent fiber (ADF) at 12 and/or 24 h of rumen incubation. FA in barley grain was more degradable than the pCA (P < 0.05). There were no differences (P > 0.05) in effective degradability of DM (EDDM) and EDFA, but significant differences in EDpCA (P < 0.05). Barley hull was strongly correlated to NDF, ADF, ADL, hemicellulose and cellulose (R > 0.78, P < 0.001) and correlated to FA (R = 0.57, P < 0.05) but not to pCA (R = 0.42, P > 0.05) in original samples. FA and pCA were highly and positively correlated to NDF, ADF, ADL, hemicellulose, cellulose, mean/median particle sizes, and rumen indigestible DM, NDF and ADF at either 12 or 24 h (P < 0.05). Mean/median particle size of barley grain positively influenced the rumen indigestible DM, but not others (FA, pCA). The results implied that reduction of barley hull, FA and pCA contents could increase the degradability of barley grain in rumen. Multi-regression with best model variable selection analysis revealed that FA was the factor most inhibiting to DM degradability of barley in rumen, and was the most effective factor to predict DM degradability, while hull was the most effective factor to determine NDF degradability in rumen. Both hull and FA affected ADF degradability in the rumen. The results indicate that breeding or identifying barley varieties with lower hull and FA contents would result in higher degradability, higher energy density and higher quality barley and improve nutrient availability of barley.