GENOTYPIC DIFFERENCES IN ROOT MORPHOLOGY AND PHOSPHORUS UPTAKE KINETICS IN BRASSICA NAPUS UNDER LOW PHOSPHORUS SUPPLY

Application of phosphorus (P) fertilizer is important in crop production because of the low bioavailability of phosphorus to plants in both acidic and calcareous soils. Although rapeseed (Brassica napus) is generally sensitive to P deficiency, different cultivars differ widely in this respect. Differences in P uptake and utilization between two rapeseed cultivars, one P-efficient (‘97081’) and one P-inefficient (‘97009’), were evaluated in solution culture by studying the changes in root morphology and parameters of P uptake kinetics in response to low-P stress. The P-efficient cultivar had lower Km and Cmin values and higher Vmax and developed longer and denser lateral root hair with greater number of root tips and branches under low-P stress, which resulted in a better developed root system and more efficient uptake of P. That, in turn, led to higher concentration and accumulation of P in the plants, culminating in higher biomass production. However, P utilization efficiency (biomass production per unit P accumulated in plant) of the P-efficient ‘97081’ was lower than that of ‘97009’ when P was deficient. These results suggest that P efficiency in rapeseed is due to a better developed root system as well as efficient uptake of P.     

增值尿素对小麦产量、氮肥利用率及肥料氮在土壤剖面中分布的影响

本研究利用同位素15N尿素,采用尿素熔融工艺分别制备了普通尿素（U）、 海藻酸增值尿素（AU）、 腐植酸增值尿素（HAU）和谷氨酸增值尿素（GU）试验产品,运用土柱栽培试验研究等氮量条件下（N 0.1 g/kg 干土,以030 cm土层干土重量计算）3种增值尿素产品对小麦产量、 氮肥利用率和肥料氮在土壤剖面中分布的影响。主要结果, 1）与U相比,AU、 HAU和GU处理均可显著提高小麦籽粒产量,增加幅度分别为7.12%、 13.63%和3.65%; 2）小麦吸收的氮素中有44.8%~48.0%来自肥料氮,AU、 HAU、 GU处理的小麦地上部吸收的肥料氮量均显著高于U处理,分别高出4.83%、 7.41% 和 3.12%; 3）虽然所有处理土壤残留的肥料氮均主要集中在050 cm土层中,U处理在5090 cm层次土壤肥料氮累积量显著高于AU和HAU处理; 4）AU、 HAU和GU处理的小麦氮肥表观利用率分别较U处理显著提高6.38、 15.63、 3.08个百分点,HAU和AU处理的15N利用率分别较普通尿素高出3.70和2.41个百分点,AU、 HAU和GU处理的肥料氮的损失率分别比普通尿素显著降低7.64、 9.52和2.19个百分点。     

铁、锌配施对藿香生长、产量及有效成分的影响

为探究铁、锌不同浓度配施对藿香生长、产量及有效成分的影响,以藿香为试验材料,采用双因素随机区组设计,研究铁锌配施对藿香生长、产量、各部位铁锌分配及挥发油含量的影响。结果表明,叶面喷施铁锌肥能显著影响藿香的生长发育、产量和挥发油成分,显著影响藿香的抗氧化酶活性,显著提高淀粉、还原糖、可溶性糖和可溶性蛋白含量,通过影响氮代谢相关酶活性间接影响植株氮代谢过程。叶面施铁对藿香产量的影响大于叶面施锌,铁锌配施的增产效果优于单独施用铁、锌肥;综合考虑藿香的生长和产量指标,认为Fe₁Zn₁(0.2%铁,0.1%锌)为铁锌配施的最优处理组合。施用锌铁肥能够增加藿香各部位的铁锌含量,锌在不同部位的含量呈叶>根>茎的变化趋势,铁在不同部位的含量呈根>叶>茎的变化趋势,锌主要集中在藿香叶片,而铁则主要集中在藿香根部。高浓度的叶面施铁有助于叶片Ca含量的累积。铁锌配施能显著提高藿香挥发油含量,并影响挥发油成分,其中D-柠檬烯含量最高,在Fe₁Zn₂处理时达到最大值(22.99%)。综上,合理配施铁锌肥能提高藿香主要化学成分的含量,但过高浓度的施用增产效果并不明显。本研究结果为铁锌肥在藿香生产中的应用提供了理论依据。     

Effect of silicon on photosynthetic gas exchange,photosynthetic pigments,cell membrane stability and relative water content of different wheat cultivars under drought stress conditions

This study aims to explain the effects of silicon (Si) foliar application on gas exchange characteristics, photosynthetic pigments, membrane stability and leaf relative water content of different wheat cultivars in the field under drought stress conditions. The experiment was arranged as a split-split plot based on randomized complete block design with three replications. Irrigation regime (100%, 60%, and 40% F.C.), silicon (control and Si application) and wheat cultivars (Shiraz, Marvdasht, Chamran, and Sirvan) were considered as main, sub and sub-sub plots, respectively. This study was carried out at the Research Farm of the Collage of Agriculture, Shiraz University, Iran, during 2012–2013 growing season. The results showed that foliar application of silicon increased the leaf relative water content, photosynthesis pigments (chlorophyll a, b and total chl and carotenoids), chlorophyll stability index (CSI) and membrane stability index (MSI) in all wheat cultivars, especially in Sirvan and Chamran (drought tolerant cultivars), under both stress and non-stress conditions. However, more improvement was observed under drought stress as compared to the non-stress condition. In contrast, these parameters decreased under drought stress. Si significantly decreased electrolyte leakage in all four cultivars under drought stress conditions. Furthermore, the intercellular carbon dioxide (CO₂) concentration (C_i) increased under drought stress. Si application decreased C_i especially under drought stress conditions. Net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (g_s) were significantly decreased under drought conditions. Under drought, Si applied plants showed significantly higher leaf photosynthesis rate, transpiration rate, and stomatal conductance. Intrinsic water use efficiency (WUEi) and carboxylation efficiency (C_E) decreased in all cultivars under drought stress. However, the silicon-applied plants had greater WUEi and C_E under drought stress. The stomatal limitation was found to be higher in stressed plants compared to the control. Exogenously applied silicon also decreased stomatal limitation. Overall, application of Si was found beneficial for improving drought tolerance of wheat plants.     

地理因素辅助的黄土高塬典型流域面雨量制图效果比较与评价

为了获取适宜的黄土高塬流域面雨量计算方法,选择算术平均(Am)、泰森多边形(Tsn)、普通克里金(OK)、泛克里金(UK)、反距离权重(IDW)、简单克里金(SK)、考虑海拔的简单克里金(SK_EL)以及将海拔和空间坐标信息作为辅助因子的简单克里金(SK_EXY)和地形插补法(Tr)等9种方法计算了环江下游流域2006—2011年面雨量。结果表明:(1)各年面雨量Am法全流域只有1个数值,无空间分布,Tsn法呈斑块状分布,IDW法在站点周围空间趋势表达不连续,其余6种基于克里金方法的面雨量空间变化趋势基本一致,均是从东南向西北连续递减的等值带,其中OK的插值曲面最平滑,Tr与SK法的结果更加符合降雨随地形的变化趋势;(2)24站测值为基础的单年和多年交叉验证结果均表明各种方法插值所得面雨量的精度以考虑高程和站点空间信息的Tr法最高,SK_EXY其次,并没有一种插值方法在所有的精度检验指标中都最差;(3)当只考虑面雨量值不考虑其空间分布时,可以选择Am与Tsn法相结合,其值接近各种方法的均值,而当综合考虑面雨量值及其空间分布时,则宜选择Tr和SK_EXY法。     

Study the Effects of Siderophore-Producing Bacteria on Zinc and Phosphorous Nutrition of Canola and Maize Plants

Plant growth-promoting rhizobacteria (PGPR) are soil bacteria that are able to colonize rhizosphere and to enhance plant growth by means of a wide variety of mechanisms. In the present study, Myristica yunnanensis and Stenotrophomonas chelatiphaga strains were recognized as new records in Iran flora. According to the results, these strains significantly affected plants’ zinc and phosphorous contents which could be due to the production of phytosiderophore. Siderophore-producing bacteria increased canola zinc (Zn) content as strategy-I plant, while in maize, it can be said that probably the effect of phytosiderophore produced by plant on increasing root and shoot Zn content was more than siderophore produced by bacteria. These isolates could be used as bio-input for improving the plant productivity as a substitute to chemical fertilizers and also to correct the nutrient deficiencies in canola and maize for sustainable agriculture.     

优化灌溉制度提高苜蓿种植当年产量及品质

为探讨灌溉定额及分配对滴灌苜蓿种植当年生产性能及水分利用效率的影响,该研究设3种滴灌灌溉定额,分别为3 750(W1)、4 500(W2)、5 250 m3/hm2(W3),且在W2处理下,设3种灌溉定额分配模式(Q1:刈割前灌溉本茬次总灌水量的35%+刈割后灌溉本茬次总灌水量的65%;Q2:刈割前灌溉本茬次总灌水量的50%+刈割后灌溉本茬次总灌水量的50%;Q3:刈割前灌溉本茬次总灌水量的65%+刈割后灌溉本茬次总灌水量的35%)。结果表明,滴灌苜蓿种植当年,不同灌溉量条件下,苜蓿的株高、叶茎比、茎粗、生长速度、干草产量、粗蛋白(crude protein,CP)含量均为W3W1处理,中性洗涤纤维(neutral detergent fiber,NDF)、酸性洗涤纤维(acid detergent fiber,ADF)含量为W3W2处理,水分利用效率(water use efficiency,WUE)为W1W3处理;不同灌溉定额分配条件下,苜蓿的株高、叶茎比、茎粗、生长速度、干草产量、CP、WUE均为Q1Q3处理,且Q1处理的干草产量最高达到9 916~10 172 kg/hm2,WUE为3.31~3.39 kg/(mm·hm2),NDF、ADF含量为Q1Q3处理。适宜的灌水量(4 500 m3/hm2)有利于苜蓿种植当年干草产量的提高,并保持较高的粗蛋白含量和相对较低的纤维含量;刈割前灌溉本茬次总灌水量的35%,并在刈割后灌溉本茬次总灌水量的65%,有利于苜蓿种植当年干草产量的提高及营养品质的改善。     

Ecophysiological characteristics of five weeds and a wheat crop in the Indo‐Gangetic Plains,India

The objective of this research was to compare selected ecophysiological parameters for a wheat crop found in the Indo‐Gangetic Plains of India and its five dominant weeds. The dominant and regionally ubiquitous weeds in the wheat field that was selected for the study were Anagallis arvensis, Chenopodium album, Melilotus albus, Phalaris minor and Rumex dentatus. Taller weeds, such as C. album and P. minor, constituted one group along with the crop, with a low photosynthetic rate, specific leaf area, leaf nitrogen mass basis, chlorophyll content, photosynthetic nitrogen‐use efficiency and leaf area ratio, in comparison to shorter weeds, such as A. arvensis, M. albus and R. dentatus, which formed another group with a high photosynthetic rate, specific leaf area, leaf nitrogen mass basis, chlorophyll content, photosynthetic nitrogen‐use efficiency and leaf area ratio. Interspecific variations in the photosynthetic rate were driven mainly by variability in the specific leaf area and leaf nitrogen content. The taller weeds and the crop had a low specific leaf area later in the season, whereas the smaller weeds had a relatively high specific leaf area, which might be an adaptation to the shaded environment below the canopy. The result indicates that any weed management in the wheat fields of the Indo‐Gangetic Plains will need two different approaches because of the different strategies followed by the two weed groups that were identified in the present study.     

玉米根系形态对光照、氮水平反应的基因型差异

用溶液培养的方法 ,研究了光照、以及氮水平对不同氮效率玉米自交系根系形态养分吸收的影响 ,研究结果表明 ,提高光照水平有助于光合产物向根系分配 ,表现为总根长、根体积、根系重量等显著增加。在不同光照水平低氮胁迫时 ,氮低效品种白瓷与其它三个品种相比 ,根系的形态指标均有不同程度的降低。在高光强 ,0 .4 mmol/ L氮水平胁迫时 ,与氮高效品种 4 78相比 ,根系体积减少 2 7.54% ,根干重减少 2 1.2 4 % ,并降低了根系的吸收效率 ,同时也表明 ,光照与氮水平对光合产物的分配具有耦合效应