施用豆科绿肥对砖红壤有效磷含量的影响

土壤缺磷是热带和亚热带地区作物生产的主要限制因子之一。本研究分析了14份热带、亚热带豆科绿肥施入土壤后对砖红壤有效磷含量影响的时间动态变化。结果表明,施用绿肥后不同时段能不同程度地提高土壤有效磷的含量,且施用绿肥后的土壤有效磷含量显著高于不施用绿肥土壤,其中木蓝（Magnolia lotungensis）对砖红壤有效磷含量增量变幅高达339%。此外,施用不同的绿肥对土壤有效磷含量的影响不同,但对土壤有效磷含量影响的基本规律一致。施用绿肥时砖红壤有效磷含量提高较大的最佳埋田时间为1个月。     

施用污泥对黑麦草生育及其元素含量的影响

将兰州市七里河污水处理厂的生活污泥施用于多年生黑麦草,藉以探讨施用量对黑麦草生长及其元素含量的影响。结果表明,随着污泥施用量(0.5～8kg/m²)的增加,黑麦草盖度,密度,地上、地下生物量以及叶绿素含量显著增加。施用后黑麦草地上部组织中N、P、K、Mg、Fe、Zn和Cu的含量增加,Mn含量减少,Ca和重金属元素Hg、Ni、Pb、As含量与对照间差异不显著,没有对黑麦草造成重金属毒害。     

葡萄锰中毒症及其相关营养元素分析

以玉溪市葡萄生产上出现的锰中毒症株及正常株为研究对象,采用田间调查与室内检测分析、锰中毒株与正常株比较相结合的方法,研究了葡萄锰中毒株及正常株叶片的N、P、K、Ca、Mg、Mn、Fe等指标,以及根际土壤的pH、有效态Mn、Fe、Ca、Mg等指标,以期为玉溪市葡萄生产上锰中毒症的防控提供技术依据。结果表明:与正常株比较,葡萄发生锰中毒株的叶片锰含量平均高达1 501.3 mg·kg^-1,比正常株的552.6 mg·kg^-1提高了1.7倍之多;P、K含量也极显著提高1倍多,而Ca、Mg含量则极显著降低近40%;锰毒株的Ca/Mn、Mg/Mn很低,分别为17.7、2.1,均显著低于正常株的98.3、10.5。葡萄发生锰中毒株的根际土壤的pH为4.29~4.35(为强酸性),有效Mn含量高达159.8~178.2 mg·kg^-1;土壤的Ca/Mn、Mg/Mn也很低,分别为7.1、0.6,均显著低于正常株的180.2、13.3。在玉溪市葡萄生产上发生的以"叶片主脉、支脉及叶脉附近的叶肉组织呈褐色状"为典型症状的锰毒株,其叶片锰吸收量过高,分析其原因是由于根际土壤pH较低为强酸性,土壤有效Mn含量过高,有效态Ca、Mg含量过低,Ca/Mn、Mg/Mn也很低所致。为葡萄生产上选择适宜土壤及其pH调节、合理平衡施肥提供参考依据。     

晋西黄土区主要造林树种耗水量测算与分析

依据水量平衡原理,采用盆栽试验分别测算了晋西黄土区主要造林树种侧柏、刺槐、杏树和梨树在其生长季(4～10月)成熟单株树木的耗水量,并根据林地土壤水分动态及土壤水分特征曲线标定的各树种无效水界值,分析了各树种土壤水分供耗特点及其有效性.结果表明:①2002贫水年生长季降水量430.7 mm,试验树种同期耗水量约为430～470 mm,树木供耗失衡;2003丰水年降水量870.2 mm,耗水量约为450～510 mm,但降雨分配不均,5月和10月树木供耗也略有失衡.②不同树种年内土壤含水量变化趋势相近,而同月耗水量差异较大,同一树种不同月耗水量差异也较大,丰水年各试验地土壤水分状况要好于贫水年.③侧柏、刺槐、杏树和梨树无效水界值为8.0%,8.4%,9.4%和10.9%,侧柏较其它树种利用水分能力最强.贫水年林外单株树木土壤含水量在一段时间内低于对应树种的无效水界值,影响树木正常生长.单株树木依靠冬季和次年春季降水补充,生长季初期都能恢复到速效水水平.     

野生欧李生长期组织器官中不同形态钙含量的变化及其相关性

 研究了野生欧李萌动期、开花期和果实发育期各组织器官中不同形态钙含量的变化及其相关性。结果表明,野生欧李对钙的吸收积累与钙的形态密切相关,木质部和花器官、果实、果柄中的钙主要以果胶钙形态为主,韧皮部和新梢中的钙主要以草酸钙形态为主。在年生长发育时期,木质部中各种形态钙含量总体呈下降趋势,进入果实成熟膨大期含量回升;韧皮部中各种形态钙含量总体呈下降趋势,进入果实成熟膨大期水溶钙、果胶钙、磷酸钙和草酸钙含量略有回升;花器官和果实中各种形态钙含量变化呈“下降—增加（或下降）—下降”的变化;在果实发育期,新梢中的水溶钙、果胶钙、草酸钙和剩余钙含量明显增加,而果柄中的水溶钙含量增加最为明显。随生长发育进程各组织器官中存在钙形态转化。木质部、韧皮部、花和果实中水溶钙和果胶钙含量的年变化与相应器官中钙总量之间存在高度正相关。     

滴灌条件下核桃园土壤水分动态变化的数值模拟研究

为探究滴灌条件下核桃根系对土壤含水量的影响,试验以8 a生核桃树为研究对象,使用分层分段挖掘法分析核桃根系的空间形态分布,通过构建HYDRUS-2D模型,对有根系吸水下的土壤水分变化进行求解,并利用实测点数据校验2D模型的可用性。经过实际计算与理论分析,得出如下结论:在垂直二维剖面中,水平距树0~30 cm、垂直40~60 cm土层的细根根长密度分布最大,为1 618.216 m·m~(-3)。对比实测数据与模拟数据,结果显示RMSE均小于0.0186 cm~3·cm~(-3),ME绝对值小于0.0108 cm~3·cm~(-3),证明数值模拟效果较好,HYDRUS模型可应用于实际试验研究。将根系模块纳入模型模拟,并比照单独水流模块作用,结果显示根系对土壤含水量产生影响,使体积含水率曲线整体低于单独水作用下的含水率曲线,且两者关系差异性显著。模拟核桃生育前期土壤含水量变化,结果表明灌水后6 d至7 d内,土壤含水量存在明显减小现象,故可将生育前期灌水周期设定为6 d或7 d。     

Effect of soil moisture during stratification on dormancy release in seeds of five common weed species

Although the effects of cold stratification on the release of physiological dormancy in seeds have been studied extensively, knowledge of the role of soil moisture content on seed dormancy release during cold stratification is limited. Our study determined seed dormancy characteristics and the effect of soil moisture content on seed dormancy breakage during cold stratification in the five common weed species Amaranthus retroflexus, Chenopodium album, Chenopodium hybridum, Plantago lanceolata and Setaria glauca. Seeds of all five species were dormant at the time of harvest and their germination response to light and temperature varied. Soil moisture content had a significant effect on seed dormancy release of all species except P. lanceolata. Germination percentage of A. retroflexus, C. album, C. hybridum increased and then decreased as soil moisture content increased, regardless of germination test temperature. The optimal soil moisture content and seed moisture content for dormancy breakage of A. retroflexus, C. album, C. hybridum were 8%, 12%, 8% and 22.0%, 37.7%, 25.7% respectively. Dry storage (after‐ripening) significantly increased germination of S. glauca. Moreover, increasing soil moisture content first slowed and then increased dormancy breakage in S. glauca. These results suggest that data on soil moisture content should be incorporated into models that predict weed seed dormancy breakage and timing of seedling emergence as well as those for weed management.     

小麦水分和装满度对磷化氢吸附率的影响

在小麦含水量分别为9.3%、12.6%和14.4%,装满度分别为100%、70%、50%、30%和0%,气体浓度为100mL/m3和400mL/m3的条件下,测定小麦对磷化氢的吸附率,结果表明小麦对磷化氢的吸附率随着粮食水分增加,磷化氢浓度和装满度增大有不同程度增加.在药量较大的施药初期和装满度大时,检测到的磷化氢浓度高于设定浓度,磷化氢浓度、小麦水分和装满度较低时,小麦对磷化氢的吸附较容易达到平衡.     

Effect of feed intake level and dietary protein content on the body temperature of pigs housed under thermo neutral conditions

Feed intake and diet composition appear to affect the body temperature of pigs. Two trials were conducted to analyse the effect of feed intake level and dietary protein content on the intestinal temperature (IT) of pigs housed under thermo neutral conditions. Ten pigs (64.1 ± 1.3 kg initial body weight) fitted with an ileal cannula were used. A thermometer set to register the IT at 5‐min intervals was implanted into the ileum through the cannula. In both trials, the ambient temperature ranged from 19.1 to 21.6°C and the pigs were fed at 07:00 and 19:00 hr (same amount each time). In trial 1, the pigs were fed daily 1.2 or 1.8 kg of a wheat–soybean meal diet. The IT followed a similar pattern along a 24‐hr period regardless the feed intake level. The IT rapidly increased up to 0.61 and 0.74°C after the morning meal and up to 0.53 and 0.47°C after the evening meal in pigs fed 1.2 and 1.8 kg/d respectively. The postprandial IT was higher in pigs fed 1.8 kg after each meal (p < .05). In trial 2, pigs were fed daily 1.8 kg of a low (11%) or a high (22%) crude protein diet. The IT followed a similar pattern along the 24‐hr period regardless the dietary protein level. The postprandial IT did not differ between pigs fed the low protein or the high protein (p > .10). The IT rapidly increased up to 0.66 and 0.62°C after the morning meal in pigs fed the high‐ and low‐protein diet (p < .05), but there was no change after the evening meal (p > .10). In conclusion, the feed intake level affected the IT of pigs housed under TN conditions, but the dietary protein content had no effect.