不同耐性玉米自交系苗期根系对低钾胁迫的生物学响应

通过水培试验,以典型耐低钾玉米自交系90-21-3和低钾敏感玉米自交系835为试材,分别于4、6、7、9和10叶期测定玉米根形态、根系还原力、伤流量和干物质积累量,研究不同耐性玉米自交系苗期根系对低钾胁迫的生物学响应。结果表明,低钾胁迫下,耐低钾玉米自交系90-21-3表现为根长增幅大,根表面积、根体积降幅小,根平均直径降幅大。与低钾敏感玉米自交系835相比,低钾胁迫下耐低钾玉米自交系90-21-3的根系相对发达、根系活力强、伤流量大及干物质积累量较大。     

苜蓿和沙打旺苗期需水及其根冠比

研究苜蓿和沙打旺苗期水分利用与根冠比例。结果表明,沙打旺叶片对土壤水分的瞬时利用效率均高于苜蓿。沙打旺地下部与地上部生物量比和根长/株高比在不同水分条件下亦高于苜蓿,尤其在低水分时。在高水分下苜蓿单位水分消耗所形成的生物量较多,随着土壤含水量的降低而大幅度减少。苜蓿具有较高的蒸腾速率和较快的根系生长速率,因而造成土壤水分的过快消耗。总之,高水分生长条件易于苜蓿生产效率的发挥,但沙打旺对土壤水分环境变化的稳定性较强。结合多年的研究成果和黄土丘陵区的实际情况,提出在不同立地条件下,沙打旺可以种植在该地区的坡地,而苜蓿则应在水分条件相对较好的川地种植。     

作物根系形态对施肥措施的响应

氮磷钾是植物生长所必需的营养元素,但土壤中植物能利用的有效成分低,限制作物生长发育,而植物可以形成特有的适应机制来应对不同的生长环境。本文综述了作物为适应不同施肥条件所产生的一系列根系形态学变化。分析了不同施肥处理对作物根系形态指标(根长、根表面积、根直径、根体积和根冠比等)的影响：氮对作物影响主要在侧根,低氮胁迫下,根系纵向伸长,增加根长、根体积;低磷条件下,植物普遍抑制主根生长,刺激侧根发育生长,诱导根毛形成;缺钾抑制细根生长,根表面积、根体积等也显著降低;普遍随元素水平的提高,作物根长、根体积、根直径、根表面积和其他根系特征均呈先增加后减少的趋势,植物根系发育产生“低促高抑”的现象;有机肥比化肥可以弥补化肥养分单一和供肥不平衡的缺点,与化肥配合施用更能促进根系生长发育,增加根系体积和总表面积;作物不同基因型品种对肥料胁迫的响应也不尽相同,高效基因型具有良好的根系形态和根系分布,以获得更多的养分。为有效利用有限的肥料资源以及高效作物品种的选种提供理论基础,对作物进一步达到经济收益最大化和环境污染最小化具有重要意义。     

Nitrogen management improves lodging resistance and production in maize (Zea mays L.) at a high plant density

Lodging in maize leads to yield losses worldwide. In this study, we determined the effects of traditional and optimized nitrogen management strategies on culm morphological characteristics, culm mechanical strength, lignin content,root growth, lodging percentage and production in maize at a high plant density. We compared a traditional nitrogen(N) application rate of 300 kg ha–1(R) and an optimized N application rate of 225 kg ha^–1(O) under four N application modes: 50% of N applied a...     

Compatibility of root growth and tuber production of potato cultivars with dynamic and static water‐saving irrigation managements

The important root characteristics of root length density (RLD) and root mass density (RMD) generally differ among irrigation managements and potato cultivars. The objective of this study was to investigate the RLD and RMD variations and their functional relationships with gross potato tuber yield for two commercial potato cultivars, Agria and Sante, under different irrigation strategies. Full irrigation and water‐saving irrigation strategies, deficit and partial root drying irrigations, were applied statically (S) and dynamically (D) based on daily crop evapotranspiration. Results showed that SPRD had significantly greater RLD (3.64 cm/cm³) and RMD (132.7 μg/cm³) than other irrigation treatments. Between the potato cultivars, Agria had significantly larger values of RLD (3.50 cm/cm³) and RMD (138.7 μg/cm³) than Sante. The functional relationship between the root growth characteristics and tuber yield showed that under water‐saving irrigations, Agria increased root mass at the expense of gross tuber yield but Sante increased root mass to maintain larger gross tuber yields. However, Agria produced more roots and gross tuber yield than Sante, and it is concluded that Agria is a more drought‐tolerant potato cultivar, which is recommended for tuber production in regions where water might be scarce. It was shown that larger root production in potatoes was associated with improved tolerance to water stress.     

根施阿米西达防治番茄叶霉病效果及对番茄生长的影响

[目的]明确根施阿米西达对番茄叶霉病的防治效果、持效期及对番茄生产的影响。[方法]采用田间试验研究4个根施阿米西达达处理、1个喷施阿米西达对照和1个清水对照对番茄叶霉病的防治效果及对番茄生长的影响。[结果]根施阿米西达超过1 500ml/hm~2,药后75 d对叶霉病的防治效果均超过90%,喷施阿米西达对照的防治效果仅为22.24%,相同用药量持效期较喷雾防治至少高出20 d。阿米西达对番茄植株表现出低浓度促进生长而高浓度抑制生长的特性。[结论]综合考虑,建议春茬番茄(8.10万株/hm~2)根施阿米西达1 500 ml/hm~2预防番茄叶霉病。     

基质添加菌剂对黄瓜根际环境及产量的影响

在播种前和定植后分别向基质中添加FZB-42、GM以及Bio微生物菌剂,研究其对黄瓜生长和基质环境的影响。连续3茬试验结果表明:添加GM菌剂减缓了基质pH值的升高速度,提高了基质的电导率,改善了基质营养供应能力;FZB-42处理能显著减少基质中细菌数量,增加放线菌数量;FZB-42、GM和Bio处理的黄瓜根长分别比对照增加57.1%、51.8%和44.9%,根表面积增加了56.5%、51.5%和44.3%,根体积增加了35.4%、82.3%和61.1%;不同菌剂处理均能提高黄瓜单株产量,Bio和GM处理增产效果明显。     

梭梭根系的研究

研究内蒙古自治区阿拉善盟阿左旗吉兰泰地区天然梭梭根系形态特征与生长状况,选取不同龄级标准木,采用全根挖掘法观察根系形态特征、风干称重法计算地上与地下生物量、烘干法(105℃)测定不同深度土壤含水量。结果表明:梭梭垂直根系发达,具有迂回生长的特点;侧根少,水平根系主要分布在50～100cm土层;不同树龄梭梭根系生物量占总生物量的比重变动为35%～40%;梭梭土壤水分稳定层为40～100cm,该层土壤含水量为2%～3%。此外,还对梭梭根长与树高、地下与地上生物量关系进行了研究。     

茶树空中压条不定根原基发育影响因子研究

为了筛选出促使茶树茎段空中压条后发根的最佳技术方案,研究了成熟度、外施激素浓度、枝梢茎粗以及环割方式对根原基发育的影响.结果表明:选择生长健壮、茎粗为0.252 ～0.280 cm的当年生枝条,在黄绿色或青绿色茎段处进行传统环割,外用100 mg/L的ABT 1号生根粉处理,能有效缩短根原基发育周期.经过40～50 d...     

The effect of soil liming on shoot development, root growth, and cluster root activity of white lupin

 The effects of a limed soil upon root and shoot growth of white lupin (Lupinus albus L.) were investigated using soil tubes and pots. After 75 days in the soil tubes, the combined taproot and lateral root dry weight in limed soil (2.5% CaO w/w) was significantly less than in neutral pH soil (by 57%). However, the dry weight and numbers of cluster roots remained comparable between the treatments, demonstrating for the first time that the cluster roots respond differently to the rest of the root system. Cluster roots accounted for 17% of the total root biomass in neutral soil, increasing significantly to over 30% in limed soil. When grown for 43 days in pots containing soil with different additions of lime (0.5–2.5% CaO w/w), soil citrate concentrations were higher than in the neutral pH soil treatment in all except the 2.5% lime treatment, in which they were lower. In both experiments, shoot dry weights were lower in the presence of the limed soil compared with those in the neutral pH soil. Although a reduction in shoot dry weight was not apparent at 21 days in the limed-soil tubes, the initiation of fewer mainstem leaf primordia indicated a slower shoot development than occurred in the neutral soil. Plants grown in the limed-soil tubes showed leaf yellowing and some chlorosis within 9 days. At the final harvest, the shoot phosphorus and manganese concentrations were significantly lower in plants grown in limed soil compared with those in the neutral pH soil, whereas the concentration of calcium was higher. Received: 11 October 1999