Alfalfa ( Medicago sativa L.) is a high quality forage that is widely planted in arid and semi-arid regions of the world. Although it has high drought resistance capability, it still requires much water for growth and development. Soil water supply as one of the main factors limiting the expansion of alfalfa cultivation could severely affect its productivity. The changes in precipitation in some regions as a result of global climate change, such as exacerbation of drought, can result in the reduction of alfalfa yield and quality. Therefore, it is important to study the drought resistance mechanisms in alfalfa. Leaf is one of the most important organs linking a plant with the surrounding environment and is one of the most sensitive parts in the plant responding to changes in environmental factors. Leaf traits evolved as a result of balance (trade-off) between growth and survival (resistance and tolerance) in adverse environment, i.e., water deficient environment. However, a systematical investigation on the responses of leaf traits to drought is still lacking, and the changes in leaf traits have rarely been investigated at different plant growth stages. In addition, most of the previous studies were primarily on trees and less on herbaceous species, such as alfalfa, which differ heavily in morphological traits from trees. Therefore, in this study, a pot experiment was performed to investigate the responses of leaf traits of M. sativa ‘Longdong’ to drought at different growth stages. The aim of the study was to test the hypothesis that leaf traits in alfalfa change in different growth stages in response to water deficit. The results are as follows: (1) With the increase in soil drought, leaf dry matter content (LDMC), leaf nitrogen concentration per unit mass (LN), leaf mass per unit area (LMA), and leaf thickness (LT) increased, leaf area and leaf mass per unit area were sensitive to soil water deficit, whereas leaf area (LA) decreased, leaf phosphorus concentration per unit mass (LP) remained unchanged, and leaf length/width ratio (L/W) and leaf chlorophyll content (Chl) varied wildly without showing clear trends. (2) As the plants progressed through growth stages, LT, LDMC, L/W, and LA did not exhibit appreciable changes, whereas LN decreased, LP increased and then decreased, and LMA and Chl showed large fluctuations. (3) Pearson correlation analysis showed that L/W was negatively correlated with LN and LT, LDMC had positive correlation with LT and LMA. LMA was positively correlated with LT and LN and negatively correlated with L/W and LP. LN had a positive correlation with LT, and LA was positively correlated with LP and negatively correlated with LDMC, LMA, and LN. There was no significant correlation between Chl and other traits. Although there was no definite trend in changes in leaf traits to drought at different growth stages, the variation of leaf traits at different stages reflects a fundamental strategy of alfalfa's response to drought. To the best of our knowledge, this is the first study to elucidate the adaptation of alfalfa to drought through investigating changes in leaf traits at different growth stages.

通过盆栽控水试验,研究了不同生育时期陇东苜蓿( Medicago sativa L. cv. Longdong)叶性状对不同程度干旱的响应。结果表明:(1)随干旱加重,叶干物质含量(LDMC)、叶氮含量(LN)、比叶重(LMA)、叶厚(LT)上升,叶面积(LA)减小,叶磷含量(LP)无明显变化,叶绿素含量(Chl)和叶长宽比(L/W)波动较大。(2)随生育时期的延长,LT、LDMC、L/W和LA变化不明显,LN下降,LP呈倒"V"型趋势,LMA和Chl波动较大。(3)L/W与LN、LT显著负相关;LDMC与LT、LMA显著正相关;LMA与LT、LN显著正相关,与L/W、LP显著负相关;LN与LT显著正相关;LA与LP显著正相关,与LDMC、LMA、LN显著负相关;Chl与其他叶性状均不相关。尽管干旱下陇东苜蓿不同生育时期叶性状响应并未表现出一致的变化,叶性状的差异性变化还是部分反映了陇东苜蓿适应干旱而采取的综合策略。从不同生育时期的差异性反应角度出发,探讨干旱下的叶性状响应是阐明优良牧草紫花苜蓿水分适应性的新的尝试。

【Objective】 Ridge and furrow rainfall harvesting system was used to plant Medicago sativa, aiming to provide a theoretical basis for the planting of Medicago sativa in semiarid areas of Loess Plateau of northwestern China, where annual rainfall ranges from 250 mm to 350 mm.【Method】 The experiment was carried out in Yongdeng County, Gansu Province. Two treatments were used in the experiment: ridge membrane, rainfall harvesting area, and earth ridge, planting area, and the effect of various ridge and furrow width ratios as well as mulching methods on the growing and quality of dry farmed M. sativa were studied to select the optimum rainfall harvesting treatment. 【Result】 The results showed that ridges covered with plastic film were evidently superior to ridges compacted with soil. MR60 was found to be the best in all treatments: the emergence rate, survival rate and overwintering rate of M. sativa increased by 16.01%, 16.03% and 18.25% compared with the control group (CK), respectively. The growth rate and regeneration rate increased by 65.30% and 56.41% compared with the control group (CK), respectively. The shoot height, branches and hay yield increased by 65.12%, 29.04% and 238.20% compared with the control group (CK), respectively. The stem-leaf ratio decreased by 22.45% compared with the control group (CK). The crude protein (CP) and crude extract (EE) increased by 29.82% and 9.31% compared with the control group (CK), respectively. The crude ash (CA) decreased by 14.54% compared with control group (CK). No significant difference was found between crude fiber (CF) and the control group (CK). 【Conclusion】 Emergence rate, survival rate and overwintering rate of M. sativa increased by covering ridges with plastic film in experimental and similar areas, meanwhile, plant growth, yield and quality of hay were also significantly promoted, thus realizing the dual goals of high yield and high quality.

【目的】垄沟覆膜种植紫花苜蓿(Medicago sativa L.),为年降水量250—350 mm的中国西北黄土高原区旱作紫花苜蓿的种植提供理论依据。【方法】试验设置膜垄和土垄集雨处理,垄为集雨区,沟为种植区,研究不同沟垄宽比和覆盖方式对旱作紫花苜蓿生长及其品质的影响,并确定最优的集雨处理。【结果】各指标值反映出,膜垄处理明显优于土垄处理;所有处理中以MR60(覆膜处理,沟垄宽比为60 cm﹕60 cm)表现最优,出苗率、成苗率和越冬率分别较对照(平作,CK)提高16.01%、16.03%和18.25%,生长速度和再生速度分别较CK提高65.30%、56.41%,生长高度、分枝数和干草产量分别较CK提高65.12%、29.04%和238.20%,茎叶比较CK降低22.45%,粗蛋白(crude protein,CP)和粗脂肪(crude extract,EE)含量分别较CK提高29.82%、9.31%,粗灰分(crude ash,CA)含量较CK降低14.54%,粗纤维(crude fiber,CF)含量与CK差异不显著。【结论】在试验地区及其相似地区采用垄覆膜沟覆秸秆集雨种植紫花苜蓿,可以促进苜蓿出苗和成苗,提高苜蓿越冬率,促进苜蓿生长,显著提高苜蓿干草产量的同时有效改善干草的品质,最终实现高产、优质的双重目标。

Abstract: Subsurface drip irrigation (SDI) and regulated deficit irrigation（RDI）are two of the most water-saving irrigation technologies nowadays. In order to study effects of regulated deficit irrigation on forage water consumption, hay yield and quality of alfalfa under subsurface drip irrigation, a field experiment was carried out in 2012 at Shiyang River Drainage Basin, northwest of China. Alfalfa used for the experiment is the second cutting of the establishment year, and the cutting is separated into 3 periods, including pre-branching period, branching period and squaring period. There are seven irrigation treatments in the experiment design. Four of the seven treatments are regulated in whole growth period, lower irrigation limits respectively 70% FC (field capacity)、60% FC (field capacity)、50% FC (field capacity)、40% FC (field capacity), and three are regulated in different growth periods, lower irrigation limits of pre-branching period, branching period and squaring period of different treatment respectively (50%, 50%, 70%)FC, (60%, 60%, 70%)FC, (70%, 70%, 50%)FC. When the soil water content arrives to the designed lower irrigation limit, each plot starts to irrigate. Irrigation amount is 20mm every time. According to these treatments, the effect on water consumption, hay yield and quality of alfalfa of regulated deficit irrigation (RDI) under subsurface drip irrigation(SDI) are studied. The results show with the deterioration of the water deficit degree, alfalfa yield, water consumption, stem/leaf ratio and yield of crude protein (CP) decrease while WUE (water use efficiency) and content of the crude protein (CP) increase， and 60%FC is a critical value. When the lower irrigation limits are higher than 60%FC, hay yield of alfalfa decrease non-significantly, however, when lower than 60%FC, hay yield decrease significantly. While RDI (regulated deficit irrigation) is taken in the whole growth period, squaring period>branching period>pre-branching period appears in water consumption rate during different periods of alfalfa. And this law is more and more significant with the increasing of the water deficit degree. When RDI (regulated deficit irrigation) is taken in branching period, water consumption rate of alfalfa have apparent compensation effect after sufficient irrigation in squaring period. Compared with regulating deficit in squaring period, taking RDI (regulated deficit irrigation) in pre-branching and branching period is more conducive to improve alfalfa quality by reducing stem/leaf ratio and improving content of crude protein (CP) and yield of crude protein. When lower irrigation limits of pre-branching period, branching period and squaring period are 60%FC, 60%FC and 70%FC respectively, alfalfa has the highest crude protein yield (846.11kg/hm2). This study reveals the effects of RDI on water consumption, yield and quality of alfalfa under SDI and provides an experimental base of high quality, high yield and water saving in alfalfa industry in arid areas.

地下滴灌技术是最为节水的灌溉技术，为了推进地下滴灌技术在紫花苜蓿生产中的应用，2012年在甘肃武威开展了大田试验，通过对建植当年第2茬苜蓿不同生育期设置不同的亏水处理，研究了地下滴灌条件下调亏灌溉对紫花苜蓿耗水、产量和品质的影响。结果表明：随亏水程度的加重，紫花苜蓿的产量降低，耗水量减少，水分利用效率（WUE）提高，干重茎叶比降低，粗蛋白含量提高，粗蛋白产量降低；全生育期调亏，生育期间的耗水强度呈现现蕾期>分枝期>分枝前期的规律，并且随着亏水程度的增加，规律愈加明显；分枝期调亏的紫花苜蓿，在现蕾期复水后耗水强度有明显的补偿效应；与现蕾期调亏相比，分枝前期和分枝期调亏有利于降低茎叶比，提高粗蛋白质量分数和粗蛋白产量。该研究揭示了地下滴灌条件下不同调亏处理对紫花苜蓿耗水、产量和品质的影响，为干旱地区优质、高产、节水苜蓿的生产提供了试验依据。

The effects of growth and biomass accumulation under different soil water stress (90% of field capacity,70%,40%,20%) on Medicago sativa cv. Xinjiangdaye were studied in the pot method. The results showed that height,diameter,number of branches and lateral roots were higher than other treatments,fresh biomass and dry biomass of leaves,stems,root were the largest. When soil moisture content was 70% of field capacity and it was the most fitted for the growth of M. sativa cv. Xinjiangdaye. It was not conductive to the formation of M. sativa cv. Xinjiangdaye biomass when the soil moisture content is too high (90% of field capacity) or too low (20%,40% of field capacity). Soil moisture stress inhibited growth of M. sativa cv. Xinjiangdaye. Height and diameter growth rates were slowed with water stress intensification. The results helped to understand the response of M. sativa cv. Xinjiangdaye to water stress and provided a theoretical basis for the spreading and cultivation of M. sativa cv. Xinjiangdaye under water-saving irrigation in the arid zone agriculture as well as establishing lasting,stable and high-yielding grassland production system.

采用盆栽法研究了不同土壤水分胁迫(田间持水量的90%,70%,40%,20%)对新疆大叶苜蓿的生长及生物量积累的影响。结果表明,土壤水分含量为田间持水量的70%时,苗高、地径、分枝数及侧根数均高于其他处理,叶片、茎、主根鲜生物量和干生物量均最大,最适宜新疆大叶苜蓿生长;土壤水分含量过高(田间持水量的90%)或过低(田间持水量的20%,40%)时,均不利于新疆大叶苜蓿生物量的形成;土壤水分胁迫抑制了新疆大叶苜蓿的生长发育,随着水分胁迫的加剧,苗高和地径生长速度均减慢。该结果为进一步了解新疆大叶苜蓿对水分胁迫的响应规律并为其在干旱区节水灌溉农业中的推广和种植以及为建立持久稳定高产的畜牧业草业生产体系提供理论依据。

In this study,pot experiments with various cultivars of specialized end-uses winter wheat were carried out at Henan Agricultural University Research Station during 2001～2003.The results showed that as for cultivar Yumai 34,the values of its chlorophyll meter(SPAD),PSII activity (Fv/Fo) and maximal PSII light energy transformation efficiency (Fv/Fm) were the highest when soil moisture content was at 60% of field capacity (FC),but the photochemical quenching coefficient (qP),non-photochemical quenching coefficient (qN),apparent photosynthetic electron transport rate(ETR) and the ratio of PSII photochemical quantum yield (Ф2) were all increased at 80% of FC.For high-yielding cultivar Yumai 49,its SPAD,qP,qN and ETR were higher at 80% of FC,but Fv/Fo,Fv/Fm and Ф2 were less affected by FC.For cultivar Yumai 50,the values of its photosynthetic characteristics were the highest at 80% of FC,except that the qN value was the lowest.The yield and the relative content of grain protein of cultivar Yumai 34 were also increased at 60% of FC.Furthermore,there was a significant difference among grain yields.The relative contents of grain protein of cultivars Yumai 49 and 50 were improved at 40% of FC,while the highest yields were obtained at 80% of FC.There were significant differences in the grain yields of Yumai 49 and 50 among different soil moisture treatments.

采用盆栽方法,研究了土壤水分对专用小麦生育后期光合特性及产量的影响.结果表明,强筋小麦豫麦34旗叶叶绿素计读数(SPAD值)、PSⅡ活性(Fv/Fo)和PSⅡ最大光能转换效率(Fv/Fm)在土壤相对含水量60%(FC)的条件下最高,光化学猝灭系数(qP)、非光化学猝灭系数(qN)、有效电子传递速率(ETR)和传递的量子产率(Φ2)在80%FC下最高;高产小麦豫麦49旗叶SPAD值、qP、qN、ETR均以80%FC下最高,Fv/Fo、Fv/Fm和φ2受土壤水分影响不大;弱筋小麦豫麦0,除qN在80%FC下最低外,其余光合特性参数均以80%FC的条件下最高.豫麦34产量和蛋白质含量均以60%FC最高,且产量达极显著差异;豫麦49和豫麦0籽粒蛋白质含量以40%FC最高,籽粒产量以80%FC最高,且豫麦49产质差异均达显著水平,而豫麦0的产量差异达极显著水平.

采用叶面喷施的方法,研究了喷施不同浓度锰对紫花苜蓿草产量和营养品质的影响.结果表明,喷施硫酸锰可显著(P＜0.05)提高苜蓿草产量,以喷施锰浓度为100 mg/kg效果最好,年总产量达14 268.88 kg/hm2,产量比对照提高24.0%.喷施硫酸锰可以显著提高苜蓿粗蛋白的含量,当喷施浓度为100 mg/kg时效果最显著;而喷施锰肥后苜蓿粗灰分有所降低;粗纤维含量有增加的趋势;不同茬次对粗脂肪含量影响效果有较大差异,以200 mg/kg(Mn2)处理更能提高粗脂肪含量;喷施锰肥对无氮浸出物含量影响不明显.营养物质的年积累量均以喷施浓度为100 mg/kg时最高.

The low availability of soil micronutrients in dryland of the Loess Plateau cannot meet the need of crop growth and then it has become one of the limiting factors for the agriculture production in this area for many years.The current cropping systems applied in the area may have effects on the availability of soil micronutrients.The long-term field cropping experiment,which composed of fallow(FA),continuous clover cropping(CC),continuous wheat cropping(WC), and clover-legumes rotation(CLR),was initiated in ...

在长期定位试验的基础上,用连续浸提方法对土壤微量元素进行形态分级,研究了长期种植作物条件下黄土高原旱地土壤中微量元素的形态组成及其在不同土壤组分间的分配特征,探讨了种植系统对土壤微量元素有效性的影响。土壤中有效态微量元素含量的剖面分布除与土壤中微量元素的全量有关外,还与不同的种植系统有关。各种植系统有效锌和有效铜含量均低于休闲土壤,有效锌以小麦连作和苜蓿连作降低最多,有效铜以小麦连作和粮豆轮作降低最多。小麦连作系统40 cm以上土层土壤有效锰含量和休闲土壤接近,40~100cm土层低于休闲土壤,苜蓿连作和粮豆轮作整个剖面土壤有效锰含量均有所增加。各种植系统40cm以上土层土壤有效铁含量均高于休闲土壤,40~100cm土层土壤有效铁分布趋势相同,其含量均随土层深度的增加而增加,并且小麦连作低于休闲土壤,粮豆轮作高于休闲土壤,苜蓿连作与休闲相近,这些结果表明长期种植作物可以显著改善土壤锰素营养和铁素营养状况。苜蓿连作和小麦连作使锌和铁从矿物态向有机结合态转化,增加了土壤有效锌和有效铁的储备,粮豆轮作系统各形态锌低于休闲土壤,并且土壤中锌的总贮量有所减少;各种植系统土壤氧化物结合态铁在耕层增加,在古耕层降低,这也表明种植作物可以活化深层土壤难溶态铁。长期种植作物使耕层土壤各形成铜含量降低，粮豆轮作和小麦连作系统古耕层土壤各形态铜含量较休闲土壤有所增加。3种种植系统碳酸盐结合部、氧化物结合态和有机结合态锰含量均有不同程度的下降，且耕层土壤交换态、碳酸盐结合态和有机结合态锰高于古耕层，氧化物结合态和矿物态锰含量低天古耕层。