Germplasm Variability and Environmental Effects on Stem Cellulose and Lignin Concentrations in Alfalfa*

Stem cellulose and lignin concentrations are major determining factors of alfalfa (Medicago sativa ssp. sativa L.) forage quality. Only limited information is available on the genetic variability and the influence of environmental effects on these two stem-quality traits. Our objectives were to: evaluate the variability for stem cellulose and lignin concentrations in modern alfalfa germplasms across several harvests; observe the environmental stability of these two quality traits in 32 alfalfa clones selected high or low for either stem cellulose or lignin concentration; and examine the relationships between these two stem-quality traits and leaf and stem crude protein (CP). Fifty alfalfa entries (cultivars and experimental populations) were established May 1993, and sampled for stem acid-detergent lignin (ADL), stem acid-detergent cellulose (ADC), and stem CP on Sep 1993, June and Aug 1994. Clones were vegetatively propagated from individual plants selected for extremes in stem ADL and ADC and transplanted into blocks at two locations in May 1994 and sampled for quality analysis in September 1994. For all samples, leaves were hand-separated from stems and stem ADL, ADC, CP and leaf CP concentration were determined using near infrared reflectance spectroscopy. Entry differences for stem ADL and ADC were detected only at the June 1994 harvest date in the cultivar study. Spearman's ranked correlations over years in the clonal study demonstrated greater environmental stability for stem ADC (r = 0.70, P ≥ 0.01) than for stem ADL (r = 0.54, P # 0.05). Environmental effects had an impact on both traits, but stem ADC showed greater potential for improving forage quality. Simple correlations showed that decreasing stem ADL or ADC would have minimal effect on leaf CP and may increase stem CP.     

Phototropic Leaflet Reorientation in Alfalfa Germplasm Selected for Leaf Color and Size

Solar tracking has been described in several agronomic and wild species, yet variation within a given species has not been reported. To address that issue, photoperiod leaflet reorientation in response to vectorial light was measured in three alfalfa ( Medicago sativa L.) germplasm pools selected from the cultivar Ladak 65. Dark-leaf germplasm responded to all photosynthetic photon flux densities (PPFD) (100 to 700 μmol/m²/s) with no detectable lag period. Following a 24-h dark treatment only high PPFD (600 to 700μmol/m²/s) elicited reorientation. Pale-leaf germplasm responded to intermediate (300 to 400 μmol/m²/s) and high PPFD in a similar manner; however, the low (100-125μmol/m²/s) PPFD treatment had little effect on reorientation. The 24-h dark treatment decreased reorientation at all PPFD. Small-leaf germplasm responded equally to all PPFD and was not affected by the 24-h dark treatment. The results suggest that available energy levels may influence the reorientation response. Carbonyl cyanide m -chlorophenylhydrazone, an inhibitor of photophosphorylation, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea, an inhibitor of non-cyclic photosynthetic electron transport, reduced reorientation only in the pale-leaf type. These results suggest that stored energy reserves were adequate to maintain leaflet reorientation in the absence of photosynthesis in all but the pale-leaf germplasm. In that germplasm photosynthetically generated energy may be required to support reorientation.     

沙引发对紫花苜蓿种子盐逆境下发芽及幼苗生理生化变化的影响

试验以紫花苜蓿品种维多利亚和金皇后种子为材料，研究了沙引发处理对高盐(0．8％NaCl)逆境下种子发芽及幼苗生理生化变化的影响。结果表明，沙引发处理能显著提高紫花苜蓿两个品种种子的发芽率、发芽势、发芽指数和活力指数，缩短平均发芽时间，显著增加幼苗干重，同时提高了过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性，减少丙二醛(MDA)的积累。说明沙引发提高了紫花苜蓿种子的活力和抗盐胁迫能力，促进了盐逆境下种子的萌发和幼苗生长。     

水热胁迫对紫花苜蓿叶表皮蜡质组分及生理指标的影响

选用2个抗旱性不同的紫花苜蓿品种,敖汉(强抗旱)和三得利(弱抗旱),在水热胁迫条件下,调查其叶表皮蜡质含量及组分变化规律、蜡质含量与气体交换参数、脯氨酸及叶片相对含水量之间的关系。结果表明,紫花苜蓿叶表皮存在致密的蜡质层,蜡质晶体结构呈片状,无特殊的晶格方向。叶表皮蜡质主要由烷(1.98%~3.38%)、醇(79.97%~84.98%)、酯类(0.08%~0.24%)及其他少量未知物质组成(7.77%~13.38%)。品种类型、环境条件共同影响叶表皮蜡质的沉积。敖汉叶表皮蜡质含量显著高于三得利。水分胁迫后烷类比例增加(81.22%~108.16%),醇类比例下降(3.32%~12.54%),强抗旱品种叶表皮蜡质含量和气体交换参数无显著变化(除胞间二氧化碳浓度显著下降外),而弱抗旱品种蜡质含量和叶片光合速率、蒸腾速率、气孔导度及胞间二氧化碳浓度均显著下降。说明表皮蜡质限制水分散失,蜡质组分中烷类物质可能主要具限制水分散失的功能。高温及水热互作胁迫处理下,紫花苜蓿叶片光合速率和蒸腾速率下降,水分利用效率提高,叶片脯氨酸含量增加,相对含水量下降,敖汉蜡质含量下降,三得利蜡质含量无显著变化。表明在严重胁迫条件下紫花苜蓿主要通过关闭气孔和渗透调节来限制水分散失。     

几种复混微肥对苜蓿微量元素营养的影响

根据河南省牧草种植区土壤微量元素含量、牧草营养及动物营养的需求特点,利用铁、锰、铜、锌、硼、钼、钴等几种微肥进行组配,来研究其对紫花苜蓿（Medicago sativa L.）微量元素营养的影响,其目的为生产提供不同用途的富含微量元素的优质牧草。结果显示：CD组配能促进紫花苜蓿第二茬铁、锌、硼,第三茬铁、锌、硼、铜含量的显著增加;及除第二茬钴外的各茬元素积累量增加。C1D1组配能促进紫花苜蓿第一茬钼、钴、硼,第二茬锌、钼、钴、硼、铁,第三茬铜、锌、硼、铁、锰含量的显著增加;及除第二茬铁外的各茬元素积累量增加。C1D2组配能促进紫花苜蓿第一茬锌、钼、钴,第二茬锌、钼、钴、硼、铁、锰,第三茬锌、钴、硼、铁、锰含量显著增加;及除第二茬铁外的各茬元素积累量的增加。C2D1组配能促进紫花苜蓿第一茬锌、钼、钴,第二茬铜、锌、钼、钴、硼、铁、锰,第三茬钼、硼、铁含量显著增加;及除第二茬铁外的各茬元素积累量的增加。C2D2组配能促进紫花苜蓿第一茬铜、锌、钼、钴,第二茬锰、铜、锌、钼、钴、硼、铁,第三茬锰、锌、钼、钴、硼、铁含量显著增加;及各茬元素积累量的增加。     

施肥对苜蓿现蕾期叶面积及比叶重的影响

用叶面积扫描仪测定苜蓿叶面积,在105℃下杀青,65℃下烘干24h,称取苜蓿叶干重,计算比叶重(SLW)。研究了不同施肥处理对3年生紫花苜蓿叶面积、叶干重及比叶重的影响。结果表明:①施肥对苜蓿现蕾期叶面积和叶干重都有一定的影响。K40P20配施不仅有利于扩大苜蓿光合叶面积,而且有利于苜蓿叶干重增加。②施肥,尤其是施氮提高了苜蓿现蕾期的比叶重,以K40P20N10配施效果最好,有助于苜蓿提高其光合速率,积累更多的光合产物。     

德钦苜蓿品比试验报告

以阿尔冈金为对照品种,对德钦苜蓿进行了品种比较试验。结果表明：德钦苜蓿生育天数为233～246天。在3个试验点种植,越冬率平均为95.3%,与对照品种阿尔冈金（均值77.4%）差异显著（P<0.05）。德钦苜蓿和阿尔冈金三年3个试验点的平均株高分别为38.2 cm和27.1 cm,差异极显著（P<0.01）。其生长速度也与阿尔冈金差异极显著（P<0.01）。2004年三个试验点德钦苜蓿的茎叶比均显著低于阿尔冈金（P<0.05）,2005年、2006年均极显著低于阿尔冈金（P<0.01）。产量测定结果表明,三年各试验点德钦苜蓿鲜草、干草产量均极显著高于阿尔冈金（P<0.01）。营养成分分析表明,德钦苜蓿在初花期和盛花期粗干物质含量分别达25.73%和28.04%,蛋白含量分别达24.50%和19.41%,体外干物质消化率分别为68.03%和66.56%,其营养品质已经达到了1级水平。抗性分析表明,德钦苜蓿能较好地适应高温高湿环境,耐贫瘠。因而从引种的角度看,德钦苜蓿适应性强、高产、优质、适口性好,是一种值得在迪庆州推广种植的优良牧草。     

硒胁迫对紫花苜蓿硒积累及矿质元素吸收的效应

为了探讨硒胁迫对紫花苜蓿硒积累及对其他矿质元素吸收的影响。以3种苜蓿阿尔冈金、大叶苜蓿、维多利亚为试材,采用土培试验方法,研究了硒胁迫对紫花苜蓿不同组织的生物量、转运系数、耐性指数、硒积累量、硒含量和矿质元素含量的影响及紫花苜蓿对硒的积累能力。结果表明:施以100μmol/L硒时,硒处理显著提高了3个品种苜蓿根、茎、叶片的硒含量、耐性指数、硒积累量和K、P、Ca、Mg元素的吸收,当硒浓度为900μmol/L时,则降低了阿尔冈金和维多利亚不同器官生物量及大叶苜蓿根的生物量积累,且降低了阿尔冈金和维多利亚不同器官及大叶苜蓿根和茎对Zn吸收积累量。不同品种间相比较,大叶苜蓿生物量、硒积累量和K、P、Mg元素吸收显著高于其他2个苜蓿,且差异显著。综合评价表明,大叶苜蓿对矿质元素和Se有较好的吸收和富集能力。     

施肥对苜蓿开花期叶面积及比叶重的影响

【研究目的】研究了不同施肥处理对3年生紫花苜蓿开花期叶面积、叶干重及比叶重的影响。【方法】用叶面积扫描仪测定苜蓿叶面积,在105℃下杀青,65℃下烘干24h,称取苜蓿叶干重,计算比叶重(SLW)。【结果】①氮、磷、钾单施或不同方式的配施均能增加苜蓿开花期叶面积和叶干重。其中以K40P60配施最有利于扩大苜蓿光合叶面积。以K40P40N10配施最有利于提高苜蓿开花期叶干重。②施氮,尤其是氮与磷配施能明显提高苜蓿开花期的比叶重,以P20N10配施效果最好。而单施磷(P20、P40、P60)、单施钾(K20、K40)或K20P20配施均不利于增加苜蓿开花期比叶重。【结论】①苜蓿施K40P60最有利于扩大开花期光合叶面积,增强光合作用。②施K40P40N10最有利于提高苜蓿开花期叶干重,从而有利于晒制干草。③施P20N10能明显提高苜蓿开花期比叶重,有助于苜蓿提高其光合速率,积累更多的光合产物。     

Effect of Variety and Seeding Rate on Establishment and Productivity of Alfalfa Sown in Autumn

Five alfalfa varieties (var.) were sown on 26 September, 1983 near Aleppo on clay or heavy clay soils, classified as Vertisols (FAO-system) or Chromoxerertic (Calcic) Rhodoxeralf (USDA-system). Irrigation was applied after planting to ensure uniform germination. Thereafter the study was conducted under supplementary irrigation. The parameters measured to estimate fresh weight (FW) and dry matter (DM) yields; plant height, ground cover and regrowth after cutting, indicated that winter-active var. ( Moapa 69, CUF 101 and Aleppo local ) resulted in better productivity than semi-dormant ( Paravivo ) and dormant ( Lebanon local ) varieties. The 2-years mean average FW yields were 70.2, 68.2, 65.2, 57.1 and 36.9 t/ha, or 16.2, 16.0, 15.5, 13.1 and 8.9 t/ha DM respectively. Forage yields were similar among the 12, 16 and 20 kg/ha seeding rates, indicating little justification for high seeding rates under good establishment conditions, even if a seeding-year yield is desired. In general, seeding rate had also no effect on plant population, which was reduced with time and towards the end of the tested period it became nearly similar and counted 137, 132 and 134 plants/m² according to the seeding rates respectively. Alfalfa yields were positively correlated with plant height, ground cover and regrowth after cutting. The highest yielding combination for FW and DM yields in Moapa 69 with 12 kg/ha seeding rate.     

Effect of Overseeding Forages into Alfalfa on Alfalfa Weevil, Forage Yield and Quality

Many alfalfa ( Medicago sativa L.) fields are sprayed each year with insecticides to control Egyptian alfalfa weevil ( Hypera brunneipennis ) and the alfalfa weevil ( Hypera postica ). Overseeding various species of legumes and grasses into established alfalfa has been proposed as a method to mitigate weevil damage without insecticides. Established fields of alfalfa were overseeded with legumes and grasses in randomized complete block designs in three years of study in a Mediterranean climate in the Sacramento Valley of California, USA. Several overseeding practices maintained or increased yields compared with the insecticide-sprayed treatment. Overseeding increased or maintained forage yield, eliminating the need for insecticides. However, overseeding did not prevent weevil damage to alfalfa. Overseeding is best used to extend the life of alfalfa stands in the final year of production, since overseeding can thin alfalfa stands. Market acceptance for mixed-species hay and harvest management of overseeded forages are the most important limitations to overseeding practices.     

喷施硫酸钴对紫花苜蓿鲜草产量及品质的影响

采用叶面喷施的方法,研究了不同施钴水平对紫花苜蓿鲜草产量和营养品质的影响。结果表明：喷施硫酸钴显著（P＜0.05）提高了苜蓿鲜草产量,其中施钴量为300 mg/kg的处理效果最好,比对照CK产量可以提高25%。同时显著能够提高苜蓿叶茎比。不同施钴水平对苜蓿营养成分的含量影响不同,苜蓿粗蛋白及磷含量随随钴量的增加而增加,而对苜蓿粗纤维、粗灰分和无氮浸出物含量没有显著的影响,粗脂肪则随着施钴量的增加而逐渐降低。不同施钴水平对紫花苜蓿营养物质产量影响不同,其中粗蛋白、粗灰分、磷和无氮浸出物产量均以Co2处理300 mg/kg最高,都要显著高于对照,粗纤维、钙产量也以Co2处理最高,但与CK没有显著差异,粗脂肪产量则以Co1处理100 mg/kg效果最好     

Evaluation of the Heterosis on Leaf Photosynthesis of Remote-Cross F1 Rice (Oryza saliva L.)

The heterosis of leaf photosynthesis was studied on the main characters included in the range from CO₂exchange rate (CER) to enzymatic activity using a remote cross F, rice. The CER was significantly higher than those of the parental strains, showing a 111 % heterosis effect on average; at the same time strong heterosis was observed for the leaf area production and growth. Also stomatal and mesophyll conductances increased in the F₁ rice, which may contribute to the increase in CER. Chlorophyll content (Ch1), soluble protein content (SPC) and ribulose 1,5-bisphosphate (RuBP) carboxylase activity (RCA) were measured as the internal factors related to photosynthesis, and compared between the F₁, rice and the parents. For all these factors, the F₁ rice showed low values compared to the parents. Positive heterosis was not expressed here. On the other hand, the specific activity of RCA (RCA/SPC) increased in the F₁, rice, showing a 120% heterosis effect. This may be regarded as one of the main causes for the increase in CER of the F₁, rice. High CER expressed as heterosis concurrently with large leaf area production is one of the important findings in our study, and this may suggest a high possibility of further improvement in biomass production or yield of rice by gathering the advantageous elements into a hybrid plant.     

Zn和EDTA对紫花苜蓿叶片光合特性的响应

为了探索提高紫花苜蓿的抗锌能力,以3个紫花苜蓿品种为试材,采用土培法,研究Zn胁迫(250μg/kg)下,EDTA对不同品种紫花苜蓿叶片锌富集量、光合色素含量及叶绿素荧光参数的影响。结果表明,在50 d时,紫花苜蓿叶片Zn的含量均显著增高,Zn+EDTA显著提高了苜蓿叶片对锌的吸收;大叶苜蓿品种叶片光合色素的含量高于对照,大叶苜蓿叶绿素a、叶绿素b、总叶绿素和类胡萝卜素的含量显著高于其他2个品种;EDTA处理可提高大叶苜蓿初始荧光值、可变荧光、最大荧光值、最大光化学效率的水平。结果显示,EDTA促进大叶苜蓿叶片的光合色素含量的增加,减少过剩激发能的耗散,提高光合电子传递效率,有效降低锌胁迫对紫花苜蓿叶片PSⅡ的伤害,提高大叶苜蓿的抗锌能力。     

施肥对紫花苜蓿分枝期光合特性的影响

【目的】研究不同施肥处理对3年生紫花苜蓿分枝期净光合速率、蒸腾速率、气孔导度等植物生理因子的影响。【方法】以加拿大进口紫花苜蓿品种——阿尔岗金为材料,采用美国LI-COR公司生产的LI-6400便携式光合作用测定系统进行测定。【结果】施氮10kg/hm2光合速率极显著地高于不施氮处理,施氮比不施氮光合速率高出8.07 μmolCO2/m2·s (24.05%);施氮10kg/hm2对水分利用率的提高具有明显的作用,氮磷配施效果更好,以P40N10配施效果最好,P20N10次之;施磷20kg/hm2叶片蒸腾速率、气孔导度和胞间CO2浓度都最高,分别达到了14.88mmolH2O /m2·s、1.01 cm/s和300μmol/mol【结论】苜蓿施氮10kg/hm2有助于提高分枝期叶片光合速率、水分利用效率。在施氮10kg/hm2水平下,施磷20—40kg/hm2范围内,随施磷量的增加水分利用率提高。施磷20kg/hm2对提高叶片蒸腾速率效果显著,并且能明显提高气孔导度和胞间CO2浓度。     

锌锰微肥对苜蓿生产的效应研究

针对河南省气候土壤特点、锌锰钼肥的生理功能以及牧草生产利用中存在的问题,对Zn、Mn两种微肥在紫花苜蓿（Medicago sativa L.）优质牧草生产中的配施技术进行了研究。结果表明：紫花苜蓿的有效范围为400~500mg/kg,最佳浓度为430mg/kg。430mg/kg的Zn肥与380mg/kg的Mn 肥结合使用,效果更好,可使牧草产量提高约10.7%,种子产量提高13.7%。     

CO2浓度对大豆叶片气孔特征和气体交换参数的影响

利用可精准控制CO₂浓度的大型气候箱设置7个CO₂浓度处理(400、600、800、1000、1200、1400和1600 μmol mol ^-1), 对大豆进行CO₂浓度富集的室内培养试验。结果表明, CO₂浓度升高显著减小大豆叶片近轴面的气孔密度和远/近轴面的气孔面积指数。当CO₂浓度为400 μmol mol ^-1时, 远轴面气孔分布最规则, 提高CO₂浓度导致远轴面气孔的不规则分布; 与远轴面相反, CO₂浓度升高导致近轴面气孔的空间分布更加规则, 即在较高CO₂浓度处理下的Lhat(d)最小值均低于对照组。不同叶面(远/近轴面)气孔特征对大气CO₂浓度变化的响应存在明显差异, 但大豆可以通过调整气孔形态特征和气孔空间分布格局进一步改变叶片的气体交换参数。研究结果有助于从气孔特征响应的角度深入理解CO₂浓度对大豆叶片气体交换过程产生的影响。     

接种不同根瘤菌对紫花苜蓿固氮效能及生物量的影响

为了在晋北生态区给主要推广品种筛选适宜的高效根瘤菌,使紫花苜蓿-根瘤菌共生体充分发挥共生固氮作用,建立高效、高产、优质紫花苜蓿生产体系。将中国农业科学院菌种保藏中心筛选出的9株紫花苜蓿根瘤菌作为试验材料,以山西大同地区的土壤为基质,结合温室盆栽和田间试验,比较供试材料的结瘤数、固氮酶活性、株高、生物量等指标的变化情况。筛选出适合供试材料巨能耐盐紫花苜蓿品种的4株高效根瘤菌CCBAU30015、CCBAU NMC024-1、HBU07004和CCBAU30198,并将这4株菌进行田间接种效果验证。结果表明,接种CCBAU30015、CCBAU NMC024-1、HBU07004和CCBAU30198后,全年干草产量分别比对照增加18.7%,15.8%,11.3%和13.3%,单位面积蛋白质产量分别比对照增加10.9%,10.2%,9.7%和10.1%,其中,CCBAU30015表现最为突出,在各个指标上与对照间差异均显著(P0.05)。说明通过土壤筛选的高效根瘤菌可以应用到实际生产中。     

低磷胁迫对不同水稻品种幼苗光合作用的影响

低磷胁迫下,水稻叶片的无机磷含量、光合速率、RuBP羧化酶活性下降.与低磷敏感品种沪占七相比，耐低磷品种大粒稻无机磷含量、RuBP羧化酶活性下降的幅度更小.在低磷胁迫初期(10 d)较低光强下，大粒稻与沪占七光合速率受低磷的影响相近，而较高光强下以及胁迫后期(20 d)大粒稻受低磷影响较小.叶绿素荧光参数测定表明，在低磷胁     

水稻库/源比对叶片光合作用、同化物运输和分配及叶片衰老的影响

两系杂交稻Ｎ３１ＳＳ／Ｐ４０水培稻株不同库／源比值株剑叶光合速率在灌浆结实前期去叶处理明显高于对照,去１／２花则降低光合速率;灌浆中,后期处理间差异较小。改变库／源比后１－７去,去叶处理剑叶的ＲｕＮＢＰ羧化酶活性,光合磷酸化和Ｈｉｌｌ反庆活性,蔗糖磷酸合成酶活性,叶片中无机磷含量,被同化碳在醇溶部分分配比例及光合同化物从剑叶输出的速率均明显高于对照,而叶片中蔗糖和淀粉含量低于对照。