Growth Responses of Twelve Wheat Cultivars and their Phosphorus Utilization from Rock Phosphate

Growth responses of 12 wheat cultivars and their phosphorus utilization were studied in a greenhouse. They were grown for 18 days in a solution containing rock phosphate as the phosphorus (p) source. Biomass of 26 day old plants of all the cultivars varied significantly whereas their shoot to root ratio stayed constant. The dry matter yield of all the 12 cultivars was significantly correlated with the p uptake (r = 0.74). Whereas the higher p uptake by all the cultivars was significantly (P < 0.01) related to the drop in the root medium pH, which was presumably owing to the H⁺ efflux from their roots. The wheat cultivar Blue Silver proved to be the most efficient p user and therefore seems to have the highest potential of making best growth in soils with poor p availability among the 12 wheat cultivars under investigation.     

不同气体配比对丰水梨采后贮藏效果的影响

采用不同的气体配比(O2∶CO2)处理丰水梨,探讨(0±0.5)℃、相对湿度95%条件下贮藏140 d期间果实品质的变化规律。结果表明,丰水梨果实的可滴定酸含量及果实硬度在贮藏过程中呈逐渐下降的趋势,其中2%O2+1%CO2和5%O2+5%CO2两个处理的果实硬度和可滴定酸含量显著低于对照(20.9%O2+0.03%CO2)(P0.05),5%O2+1%CO2、5%O2+3%CO2、10%O2+1%CO2和10%O2+3%CO2处理组高于对照;VC含量与可溶性固形物含量(SSC)的变化趋势均为先升后降,其中5%O2+1%CO2处理出现峰值最迟且峰值较高;各组丰水梨果实的失重率变化不明显。本试验中以5%O2+1%CO2处理的丰水梨果实贮藏品质最佳。     

高浓度CO2气调防治谷蠹及杂拟谷盗的研究

将谷蠹Rhyzopertha dominica(Fab.）成虫及杂拟谷盗Tribolium confusum Jacquelin du val卵、幼虫、肾和成虫分别暴露于35％CO2和11％O2，35％CO2和21％O2，75％CO2和11％O2，75％CO2和21％O2四种气调环境中12、24、36、48、60、72、84、96、108、120小时，结果表明谷蠹成虫对四种气调环境都很敏感，其LT50分别为34.6、42.0、18.6、17.8小时。杂拟谷盗成虫较耐35％CO2、11％O2及35％CO2、21％O2气调环境，处理120小时后，成虫死亡率低于12％。卵及幼虫对四种气调环境较为敏感，蛹对35％CO2、11％O2的耐受性比35％CO2、21％O2强，前者LT50为2248.3小时，后者为124.5小时，杂拟谷盗卵、幼虫、蛹及成虫对四种气调环境敏感顺序为：卵＞幼虫＞蛹＞成虫。     

蘑菇低温气调保鲜的初步研究

采用正交实验方法，探讨了NaCl浓度、护色时间及控制贮藏环境温度等3个因素对蘑菇子实体的开伞率、PPO酶活变化量及ADF质量分数的影响。结果表明，蘑菇经适当处理，可有效抑制其开伞和品质变化。采用均匀试验设计回归分析程序对实验结果进行拟合，得到以蘑菇开伞率、PPO酶活变化及ADF质量分数为因变量，3个因素的水平编码号为自变量的回归方程估计值与实测值吻合。相对于单纯低温保鲜，采用低温气调保鲜的蘑菇，其品质和理化指标更为理想。     

The selektron of the Institute for Horticultural Plant Breeding (IVT), Wageningen,the Netherlands

Summary A facility is described consisting of four growth rooms of 100 m² each in which temperatures and light intensities prevailing in glasshouses in winter in the Netherlands can be controlled.     

施用不同缓释肥料对春小麦产量的影响

通过对Triabon和Field两种缓释肥料的试验研究,结果表明:缓释肥料具有良好的养分缓释效果,肥效期均可达到100d,但Triabon缓释效果优于国产的Field。施用缓释肥料Triabon600kg/hm2,春小麦单产7083kg/hm2,比对照增产42 5%,且穗粒数、千粒重均较对照增加明显,Field次之。施用缓释肥料的籽实、茎叶N、P、K携出量分别比等NPK养分混配肥料S提高了2 4%～14 8%,5 6%～21 2%,8 0%～11 3%。缓释肥料的N利用率达到37 2%～60 9%,P利用率24 7%～40 3%,K利用率71 3%～81 9%,减少了肥料损失。     

不同施肥方法对缓释尿素的肥效及氮素利用率的影响

以水稻和玉米为供试作物进行盆栽试验和田间试验。结果表明,水稻和玉米的增产效应均表现为;缓释尿素基追施结合处理>普通尿素基追施结合处理>缓释尿素一次性基施处理>普通尿素一次性基施处理。处理间差异达显著或极显著水准。相比之下,一次性基施改为基追施结合的增产幅度要优于尿素缓效化的肥效。两种作物对尿素的氮素利用率范围值分别为54.8%~70.1%(水稻)和53.6%~59.1%(玉米),其规律与上述肥效相吻合,也是各处理增产的内在原因。在水稻和玉米生产中应推荐在施用PK肥基础上,缓释尿素85%作基肥、15%作追肥这一施肥方法。     

腐植酸包裹型长效尿素肥效机理初步研究

采用盆栽、试管培养及室内分析相结合的方法 ,研究了腐植酸包裹型尿素的氮素曲线释放特点以及渗透性包膜的抑制作用 ,进而提高该肥料利用率 ,肥效期延长     

固定道保护性耕作节能效果试验研究

固定道保护性耕作限制了机具对土壤的普遍性压实，提高了拖拉机牵引性能，降低了能耗。在北京郊区青云店镇试验区，设置固定道及非固定道保护性耕作对照区。通过播种机开沟器阻力正交试验及牵引阻力测试试验，研究固定道保护性耕作对播种、深松作业的牵引力及油耗的影响。试验表明：在0．05的置信水平下，对比作业速度、深度租土壤坚实度因素，土壤坚实度因素因田间分布均匀性较低，对开沟阻力波动影响最为显著；非固定道保护性耕作因轮胎压实，破坏了表层土壤均匀性，造成作业负荷变动大，加剧燃油消耗；相对于非固定道保护性耕作，按华北小麦-玉米一年两熟地区两年一深松模式估算，固定道保护性耕作仅播种、深松两项作业一年每公顷节省15．7L柴油；固定道保护性耕作因减少了压实面积，从而可以提高拖拉机田间作业的牵引性能，减小机具的作业阻力，降低燃油消耗，达到减少压实、节约能耗的作用。     

A comparison of regression methods for estimating soil-atmosphere diffusion gas fluxes by a closed-chamber technique

Continuous changes in methane (CH₄) and carbon dioxide (CO₂) concentrations inside a closed chamber were measured on the forest floor at three sites: a deciduous forest and a coniferous forest in Hokkaido, Japan, and a birch forest in West Siberia, Russian Federation. Flux estimations by three types of regression methods, exponential, nonlinear, and linear, were examined using field-collected concentration data. The pattern of change with time of the gas concentration in the headspace differed, mainly according to site but also, to a lesser extent, according to the gas. This was a function of both the chamber height and surface soil property relating to soil gas diffusion and the gas concentration profile. Flux estimations did not differ statistically between the exponential and nonlinear methods for either gas at any site, because both of those regression methods were based on diffusion theory. However, the flux values estimated by linear regression were significantly different from those estimated by the other two methods for both CH₄ and CO₂ at the deciduous forest site and for CO₂ at the coniferous forest site. Shortening the chamber deployment period improved the linearity of the curve, but did not completely eliminate the error. Our results suggest that linear regression is not a good model of the change in headspace concentration with time.