通辽地区甜菜最适种植密度分析

在通辽地区以田间4种密度条件下研究了甜菜株高、根粗、鲜重冠根比等生理性状的变化及其与块根产量、舍糖率、产糖量的关系。结果表明,甜菜株高、鲜重冠根比随着种植密度的增加而增加;根粗、块根鲜重、叶鲜重随着种植密度的增加而降低。在产量、含糖率、产糖量上都表现出：B3处理〉B2处理〉B1处理〉B4处理。综合评析得出B3处理（即9．0万株／hm^2）为最适密度处理。     

蒺藜苜蓿LysM类受体激酶的研究进展

LysM类受体激酶属于多基因家族,其胞外域直接参与几丁质、肽聚糖和脂壳寡糖等糖化合物的感知,从而激活植物免疫或共生信号转导。豆科模式植物蒺藜苜蓿中第1个LysM受体基因LYK3的功能于2003年被表征。此后,越来越多的LysM类受体激酶的功能相继被鉴定。本文总结了蒺藜苜蓿LysM类受体激酶家族基因功能特征,综述了蒺藜苜蓿LysM类受体激酶家族分别在根瘤共生、菌根共生和免疫感知等方面的研究进展。研究发现,蒺藜苜蓿LysM类受体激酶家族基因数量的扩张导致了功能分化,但也存在部分基因间功能冗余现象。此外,研究还揭示了免疫与共生信号在LysM类受体激酶介导的受体感知层面存在着密切的交联,为后续研究蒺藜苜蓿中LysM类受体激酶家族基因提供有效参考。     

Crop rotation sequencing to minimize yield losses of summer-irrigated lowland rice in Myanmar caused by the rice root-knot nematode Meloidogyne graminicola

Abstract

The effect of different rice-based crop rotation sequences on the population densities of Meloidogyne graminicola and on the yield of rice was evaluated in a microplot experiment under lowland rice field conditions. Ten treatments of cropping sequences were grown in four successive growing seasons: continuous growing of the susceptible rice cultivar Thihtatyin (rice-rice-rice-rice), four treatments of 1- season crop rotation sequences (rice-rice-chickpea-rice, rice-rice-black gram-rice, rice-rice-soybean-rice, rice-rice-cowpea-rice), and five treatments of 2-season crop rotation sequences (groundnut-rice-chickpea-rice, green gram-rice-black gram-rice, cowpea-rice-soybean-rice, sesame-rice-cowpea-rice, sunflower-rice-sesame-rice). Population densities of M. graminicola recovered from the rice plants and the nematode multiplication factors (Mf) in the soil in the continuous rice cropping sequence (rice-rice-rice-rice) was the highest among the ten cropping sequences. Lowest nematode Mf in the soil was observed in the 2-season crop rotation sequence sunflower-rice-sesame-rice and the highest was observed in the 1-season crop rotation sequence rice-rice-cowpea-rice among the nine crop rotation sequences. Highest rice yield was obtained in the 2-season crop rotation sequences green gram-rice-black gram-rice, sesame-rice-cowpea-rice and sunflower-rice-sesame-rice, which were about 2 times higher compared with the 1-season crop rotation sequences and about 3 times higher compared with the continuous rice cropping sequence.     

不同基因型柱花草的根系构型差异及其磷效率

柱花草是华南坡地果园生草栽培的重要草种,为减轻柱花草与果树的根系养分竞争,有必要筛选根系构型适宜的基因型柱花草。本试验在正常供磷条件下研究了7个基因型柱花草的根系构型特征,发现存在显著的差异,且总根长、主根长和根系表面积与生物量存在显著正相关。根据生物量和根系构型将其分为3类,选择生物量高但基根角度差异大的2个基因型(‘格拉姆’和‘184号’)进行进一步的磷效率比较研究,结果表明基根角度小的‘184号’在高磷条件下具有较高的磷吸收效率,但在低磷条件下的磷吸收效率较低,从而导致其磷效率较低。本研究表明,基根角度是影响磷吸收效率的重要因子,但是磷效率还取决于低磷条件下的生长表现;‘格拉姆’可能比‘184号’更适于用作果园间作。     

Uptake and fate of triticonazole applied as seed treatment to spring wheat (Triticum aestivum L.)

Following seed treatment of wheat (Triticum aestivum L.) with ¹⁴C-labelled triticonazole at a dose of 1·8 g kg^-1 seed, the uptake of radioactivity by shoots and roots was investigated from the two- to three-leaf stage up to the beginning of the booting phase, 80 days after sowing. Triticonazole equivalents taken up by wheat plants reached 5·7% and 14·6% of the applied dose in the shoots and the roots, respectively. Between the two- to three-leaf stage and the beginning of the booting phase, the concentration of triticonazole equivalents in the shoots decreased from 2·5 to 0·15 μg g^-1 fresh weight. This was attributed to uptake of triticonazole by roots not keeping pace with shoot growth and increased retention in the roots of triticonazole taken up. The main factor limiting the uptake of triticonazole by the roots may be the rapid growth of the uptake-active apical root parts out of the dressing zone which had formed in the soil. Distribution of triticonazole equivalents taken up by the main shoot showed a decreasing concentration gradient from the oldest to the youngest leaf. An increase in the seed treatment dose was investigated as a way to increase the concentration of triticonazole in the shoots, but its influence remained limited. © 1998 SCI     

优良当家牧草品种的适口性测定

优良当家牧草品种对四川麻羊适口性测定的结果表明：卡松古鲁狗尾草的适口性最好,其次是宽叶雀稗。不同生育期的牧草,对山羊适口性的影响亦很大,其中,以拔节期牧草的适口性最优。     

Studies of the Rhizosphere of Strawberry Plants at the Research Institute of Pomology and Floriculture in Skierniewice,Poland

Abstract

Rhizosphere studies are particularly important because of the recently introduced fertigation systems in strawberry cultivation, both in the field and under cover. Because of the need for developing fruit production in a balanced environment, rhizosphere studies help in determining precise doses of mineral fertilizers necessary for proper growth and production of economically important strawberry cultivars with specific requirements. The present experiment was carried out using rhizoboxes and determined pH changes in the rhizosphere of strawberries depending on the dose and form of nitrogen applied. The method enables visualization of pH changes in the rhizosphere and the soil as they become visible due to color changes under the influence of root exudates. To achieve this, the exposed plant roots and the entire soil mass penetrated by the roots in the rhizobox were covered with a thin (0.5 cm) agar filter containing 1% agar and 1% pH indicator (bromocresol purple). The color of the agar filter covering the roots indicates pH levels in various zones of the root system and depends on the applied forms of nitrogen. The highest pH values in the rhizosphere were measured in the root tips, lower in the middle root zone, and the lowest at the root bases. Plants supplied with N-NH4+ had the lowest rhizosphere pH, which was associated with an intensive release of H+ ions to the rhizosphere and acidification in the root zone.     

绒毛白蜡根区局部盐胁迫对其生长的影响

绒毛白蜡（Fraxinus velutina）是滨海盐渍区主要的植被和园林绿化乔木,其发达的根系易受土壤盐分异质性的影响。为探索局部盐胁迫对其生长的影响,采用分根培养桶对幼苗进行局部盐胁迫处理,分析幼苗的生长特征、光合特性、根系分布和离子积累。结果表明,局部低盐胁迫处理的幼苗生长量显著高于均匀盐胁迫和局部高盐胁迫处理;虽然局部高盐胁迫对叶片的水势无影响,但是显著降低了叶片的气孔导度、光合速率和蒸腾速率。局部盐胁迫处理中,无盐胁迫区的根系生物量显著高于盐胁迫区;与均匀盐胁迫相比,局部盐胁迫能够显著降低叶片中Na+的含量,增加K+/Na+。虽然绒毛白蜡的生长在局部盐胁迫条件下受到抑制,且局部盐分越高抑制越强,但生长量与均匀盐胁迫相比显著增高。在局部盐胁迫条件下,细根在无胁迫区的补偿性生长能够提供叶片所需水分,降低叶片中Na+的积累,增加K+含量,缓解了盐胁迫的不利影响。     

间接地下滴灌灌溉深度对枣树根系和水分的影响

为探讨间接地下滴灌及导水装置埋深(灌溉深度)对南疆极端干旱区矮化密植红枣根系生长分布特征及产量、水分利用率的影响,试验设间接地下滴灌(ISDI)3个导水装置埋深水平,分别为20、27、35 cm,以地表滴灌(DI)为对照,共4个处理,经过2~4 a的田间试验后,采用环状壕沟分层挖掘法对以枣树树干为中心,半径为1 m的90°扇形区域内0~100 cm土层进行根系取样。结果表明,相对于DI,ISDI下各根系分布较均匀,生长方向基本向下延伸;ISDI显著增加了根径小于5 mm根系根长密度,细根(根径小于2 mm)是DI的3倍,但减少了根径大于5 mm根系根长密度,相对增加了20~40 cm土层根系根长占总根长的比率;垂直方向上随着灌溉深度的增加表层根系根长密度相对减少,深层相对增加;水平方向上各处理根系根长密度基本呈现随着与树干水平距离的增加而减小的趋势,但在0~20 cm土层减小的幅度较大,在20~40 cm土层其减小的幅度较小;随着灌溉技术由DI到ISDI及灌溉深度的增加,细根分布基本呈现出由宽浅型向深根型发展的趋势。相对DI,ISDI具有较好的节水增产效果,提高产量及灌溉水生产率最大达20%。建议幼龄期南疆密植枣树的导水装置埋深为27~35 cm。研究为极端干旱区枣树适宜灌溉技术的选择及其技术要素的制定提供依据。