持续干旱胁迫及复水对橡胶树渗透调节能力的影响

干旱胁迫是影响植物生长发育的重要因子。为了研究橡胶树的抗旱能力及其抗旱机制,以橡胶树为供试材料,通过盆栽试验,在温室条件下研究自然干旱胁迫和复水处理对橡胶树叶片渗透调节物质及细胞膜透性的影响。结果表明：随着干旱胁迫时间的延长,相对电导率、游离脯氨酸含量、可溶性糖含量及可溶性蛋白含量都呈现上升的趋势;复水处理后,相对电导率与可溶性蛋白含量均能恢复至对照水平;游离脯氨酸含量与可溶性糖含量呈下降趋势,但高于对照水平。综合各指标变化情况,说明橡胶树有着较强的抗旱和恢复能力。     

干旱和盐胁迫对花生渗透调节和抗氧化酶活性的影响

为明确干旱和盐胁迫对花生生长发育及衰老特性的影响,以花生品种花育25为试验材料,采用盆栽试验探究了开花期干旱和盐胁迫对花生叶片中渗透调节物质含量及抗氧化酶活性的影响。结果表明,干旱处理(D)、盐胁迫处理(S)和旱盐共同胁迫处理(DS)均增加了叶片中可溶性蛋白质、可溶性糖、游离氨基酸、脯氨酸、O_2~(-·)、MDA的含量。S处理和DS处理降低了叶片中SOD、POD、CAT活性,且随着胁迫时间的延长而持续降低;而D处理使叶片中SOD、CAT活性有所提高。复水10 d后,D处理叶片中的可溶性糖、可溶性蛋白、脯氨酸、游离氨基酸、O_2~(-·)、MDA的含量较复水前下降,除可溶性蛋白外,D处理叶片SOD、POD活性和上述指标与CK差异不显著,但DS处理叶片中的SOD、POD、CAT活性、O_2~(-·)、MDA含量与S处理均差异显著。收获期,D处理单株产量和出仁率与CK差异不显著,但DS处理的单株产量和出仁率与S处理差异显著。分析DAT9的数据得出:干旱和盐胁迫对叶片可溶性糖、可溶性蛋白、游离氨基酸和脯氨酸含量无显著的交互作用,但对SOD、POD、CAT活性和O_2~(-·)、MDA含量存在显著的交互作用,旱盐互作抑制了SOD、POD、CAT活性,加剧了对植物细胞膜的过氧化作用,MDA含量增加,最终降低了花生产量和出仁率。因此,盐胁迫下种植花生应及时补水,避免开花期干旱,减少盐胁迫、干旱胁迫和旱盐互作对花生的危害。     

干旱胁迫对金光杏梅叶片渗透调节物质和光合作用的影响

以金光杏梅盆栽幼苗为试材,研究了干旱胁迫对金光杏梅叶片渗透调节物质含量和光合作用日变化的影响.结果表明:随着干旱胁迫程度的增加,金光杏梅叶片相对含水量和叶绿素含量都明显降低;细胞质膜透性、丙二醛(MDA)、可溶性糖、脯氨酸(Pro)的含量显著增加;叶片净光合速率、蒸腾速率和气孔导度等都随着干旱胁迫的加重而降低,细胞间隙CO2浓度随着干旱胁迫的加重而升高;轻度干旱胁迫下,气孔限制是净光合速率降低的主要原因;严重干旱胁迫下,非气孔限制是净光合速率降低的主要原因.     

玉米叶片光合作用和渗透调节对干旱胁迫的响应

以2个不同抗旱性玉米品种郑单958 (抗旱性强)和陕单902 (抗旱性弱)为材料,采用盆栽控水试验,设置3个干旱处理(轻度干旱、中度干旱、重度干旱)和正常灌水,研究了干旱胁迫对2个玉米品种气体交换、叶绿素荧光参数和渗透调节物质的影响。结果显示, 重度干旱造成2个玉米品种叶片光合机构紊乱,破坏细胞膜完整性;同时增加了渗透调节物质,这对增强叶片的保水能力,维持光合速率有重要的作用。但与陕单902相比,干旱胁迫下郑单958表现出较高的最大净光合速率(P_nmax),表观量子效率(AQY),光饱和点(LSP),最大电子传递速率(J_max),最大羧化速率(V_cmax),PSII的实际量子产量(Φ_PSII)和光化学猝灭系数(q_P);较高的脯氨酸(Pro)和可溶性糖含量(SS);较低的丙二醛含量(MDA)。这些结果表明,干旱胁迫下抗旱品种郑单958具有较强的渗透物质能力,减轻细胞膜质过氧化程度,维持较高的光合性能是其适应干旱环境的生理基础。     

不同时期干旱胁迫对甘薯内源激素的影响及其与块根产量的关系

在人工控水条件下, 以抗旱品种济薯21和不抗旱品种济紫薯1号为试验材料, 设置全生育期干旱胁迫(DS)、发根分枝期干旱胁迫(DS1)、蔓薯并长期干旱胁迫(DS2)、快速膨大期干旱胁迫(DS3) 4个处理, 全生育期正常灌水(WW)为对照, 研究其对甘薯内源激素及块根产量的影响。结果表明, 与对照相比, 2个品种不同年份的所有干旱胁迫处理的鲜薯和薯干产量均显著下降。其中, DS薯干产量减产幅度最大, 济薯21和济紫薯1号3年平均分别减产44.62%和56.21%; 其次是DS1, 减产32.03%和44.03%; 再次是DS2, 减产30.41%和39.39%; DS3的减产幅度最小, 为13.66%和17.88%。抗旱品种济薯21的减产幅度小于不抗旱品种济紫薯1号。干旱胁迫抑制了甘薯地上部生长及块根的形成和膨大, 两个品种的单株叶片数、蔓长、地上部干重、地下部干重和块根淀粉率, 与对照相比, 各时期均表现为, DS的减少幅度最大, 其次是DS1和DS2, DS3的减少幅度最小。不同时期干旱胁迫均引起叶片和块根中GA、IAA和ZR含量下降, ABA含量上升。地上部干重与叶片GA、IAA和ZR含量呈显著正相关, 与ABA含量呈显著负相关; 地下部干重与块根GA、IAA和ZR含量呈显著正相关, 与ABA含量呈显著负相关。总之, 不同时期干旱胁迫均导致甘薯产量下降, 且胁迫时间越早, 对甘薯内源激素和块根产量的影响越大, 发根分枝期是甘薯对水分最敏感的时期。     

不同生长时期土壤干旱对水稻的影响

观察了水稻品种老来青在六个不同生长发育时期遭受土壤干旱的影响,其中以孕穗期受害最重,形成畸形颖花,其次是分蘗前期和灌浆乳熟期,减产亦较乡。胜利秈则是在开花期受旱害最为严重,容易形成大量白穗。稻株在拔节期和分蘗后期有较强的抗旱力。干旱减产的因素可能是多种多样的,视生长发育时期和干旱的条件而異。在孕穗期和开花期遭受短期干旱后,强烈地破坏了营养生长和生殖生长的正常相关,是减产的一个主要原因。     

不同时期干旱胁迫对谷子农艺性状的影响

采用盆栽控水方法,研究不同生育时期干旱胁迫对谷子物候期、株高、叶片数、顶叶叶面积、穗长、根轮数等农艺性状及产量的影响。结果表明,干旱延迟谷子物候期的出现;拔节期干旱对谷子株高的影响最大;干旱不会引起谷子总叶片数的改变,但对叶片发生时间有一定影响;拔节期干旱和孕穗期干旱使谷子顶叶叶面积减小;干旱抑制谷子根系的生长,但复水后生长迅速恢复。拔节期干旱对谷子农艺性状造成的影响最严重、最持久,干旱胁迫使谷子的产量降低,尤以灌浆期干旱对产量影响最显著。     

干旱胁迫对甘薯活性氧代谢、渗透调节物质、SPAD及叶绿素荧光特性的影响

为探究甘薯对干旱胁迫的应答机制及其生长需水规律,以‘商薯19’为供试材料,通过无土栽培方式,研究不同干旱强度(PEG-6000浓度分别为0%、6%、12%、18%、24%)对甘薯活性氧代谢、渗透调节物质、SPAD及叶绿素荧光特性的影响。结果表明,随着干旱胁迫强度的增加,保护酶SOD、POD、CAT、APX活性,可溶性蛋白质和可溶性糖含量均呈现先升高再降低的变化规律,且PEG-6000浓度不高于7%可诱导叶片保护酶SOD、POD、CAT和APX活性的提高。可溶性蛋白质和可溶性糖含量在PEG-6000浓度7%时值最大,较对照分别增加58.09%和161.14%。脯氨酸和丙二醛含量随干旱胁迫强度的增强而逐渐增加。PEG-6000浓度不高于3%能够刺激甘薯叶片叶绿素的生成。SPAD与干旱胁迫强度有极显著的负相关关系,两者的拟合方程y=54.354e-3.323x。初始荧光(Fo)表现出先降低再升高的变化规律,在PEG-6000浓度3%时值最低;最大荧光(Fm)、最大光化学效率(Fv/Fm)和光化学猝灭系数(qP)随干旱胁迫强度的增加表现出先升高再降低的单峰变化规律,且在PEG-6000浓度3%时值最大,与初始荧光(Fo)具有负相关关系。研究得出,土壤含水量保持在PEG-6000浓度3%,可以使甘薯幼苗保持健壮生长,实现节水灌溉,但土壤干旱强度不能超过PEG-6000浓度的7%,否则会对甘薯苗期形态特征和生理特性造成不利影响。     

外源腐胺对干旱胁迫下小麦叶片渗透调节的影响

用15%聚乙二醇（PEG-6000）模拟干旱胁迫处理,研究外源腐胺对干旱胁迫下冬小麦幼苗叶片膜质过氧化和有机渗透调节物质的影响。结果表明：在干旱胁迫条件下,外源腐胺显著提高了冬小麦叶片可溶性糖（SS）、游离脯氨酸（Pro）、游离氨基酸（TFA）含量,分别为干旱胁迫处理的1.73倍,9.51倍,1.5倍;降低了冬小麦叶片丙二醛（MDA）含量和质膜透性（PMP）,与干旱胁迫处理相比下降了82%和84.5%,显著降低了叶片膜质过氧化程度。这说明外源腐胺能改善冬小麦幼苗叶片干旱胁迫下的渗透调节能力,从而增强植株的耐旱性。     

干旱胁迫对不同大豆品种苗期叶片渗透调节物质含量和细胞膜透性的影响

研究了苗期大豆在干旱胁迫下叶片渗透调节能力与大豆抗旱性的关系.结果表明:随着干旱胁迫的加强,渗透调节物质中可溶性糖(WSS)、游离脯氨酸(Pro)含量累积显著增加,质膜透性也不断增大.且耐旱性强的品种可溶性糖(WSS)和游离脯氨酸(Pro)含量增加的幅度大于耐旱性弱的品种,而MDA含量和相对电导率则是耐旱性强的品种增幅小于耐旱性弱的品种.     

Evolutionary autoploidy in the sweet potato (Ipomoea batatas (L.) Lam.) and its progenitors

Summary The role of polyploidy in the evolution of the sweet potato. I. batatas (2n=6x=90), became more clear in 1971 when wild species with 30, 60, and 90 chromosomes were discovered. These species, I. leucantha (2x), I. littoralis (4x) and I. trifida (6x), are the progenitors of the sweet potato (6x), in an autopolyploid series with doubling of the I. leucantha B genome.In the present study the hypothesis of the origin of the sweet potato was confirmed by comparative studies on some plant characters, sexual compatibility, and the behavior of artificial hexaploids produced from I. leucantha (2x) and I. littoralis (4x).Since induced hexaploid I. leucantha exhibits weak growth, a few multivalents are formed at meiosis in the sweet potato, and there are differences in morphological and physiological characteristics between the artificial hexaploids and I. batatas, raw autoploidy seems unlikely, but a balanced or diploidised autoploidy could have been achieved by genic and chromosomal changes in the course of evolution. However, there is still sufficient homology so that meiotic pairing occurs usually between regular partners but also between homoeologous chromosomes in a certain situation.     

Development of molecular linkage maps in sweet potato (Ipomoea batatas L.) using sequence‐related amplified polymorphism markers

Sweet potato is an important food crop with high starch content. It is a hexaploid species, for which the chromosomes have not yet been well characterized. In this study, we used 856 SRAP primer pairs to analyse the 240 individuals from a mapping population, which were derived from a hybrid F₁ generation of ‘Luoxushu 8’ (female) and ‘Zhengshu 20’ (male). Genetic linkage maps of the two parents were constructed. In the female parent (‘Luoxushu 8’), the linkage map consisted of 1391 markers, and the length of the linkage map was estimated to be 10,188.4 cM with an average distance of 7.17 cM between markers. In the male parent (‘Zhengshu 20’), the final linkage map consisted of 1,112 markers, and the estimated length of the map was 9,165.17 cM with an average distance of 8.40 cM between markers. Our results provide a basis for the detailed characterization of sweet potato chromosome sequences and the development of related molecular markers.     

Impact of nitrogen supply on leaf water relations and physiological traits in a set of potato (Solanum tuberosum L.) cultivars under drought stress

Improved adaptation of potato to limited water availability is needed for stable yields under drought. The maintenance of the cell water status and protection of cellular components against dehydration are important for drought tolerance, and the N status of plants affects the regulation of various respective metabolic processes. A 2‐year pot trial with 17 potato cultivars was conducted under a rain‐out shelter including two water regimes and two N‐levels to investigate genotypic differences concerning osmotic adjustment (OA) and relevant biochemical traits in relation to nitrogen (N) supply. Drought stress resulted in a rapid decrease in the leaf osmotic potential. The N, protein and proline contents increased under drought, while the N protein/N_Kjeldahl ratio decreased. Initially, total soluble sugars increased at both N‐levels but dropped back to the control level at high N‐availability under prolonged drought while remaining high in N‐deficient plants. Results indicate that potatoes have only a limited capacity of active OA and that increasing sugar and proline concentrations are rather associated with the protection of cellular components. High N supply promoted the N protein/N_Kjeldahl ratio at short‐term drought and enhanced proline accumulation. Significant genotypic differences were observed for all investigated traits.     

Genetic variation of sweet potatoes (Ipomoea batatas L.) cultivated in Chile determined by RAPDs

RAPD (randomly amplified polymorphic DNA) technology was applied to analyze the genetic variability of sweet potato germplasm existing in Chile and elsewhere. Analysis of 28 cultivars from all over the world showed polymorphic bands with all 18 primers tested. A total of 124 RAPD bands were scored with an average of 6.9 polymorphic bands per primer. These results confirm that sweet potato exhibits high genetic variation. Two groups were distinguished: one containing Peruvian cultivars, and another containing cultivars from the rest of the world. Analysis of 14 accessions from Central Chile and one from Northern Chile showed polymorphic bands with 24 of 26 primers tested, but almost all of the 140 polymorphic bands merely showed the distinctness of the Northern accession. The almost complete uniformity of the other 14 accessions shows that sweet potato germplasm collected in Central Chile has very little genetic variability and may be derived from a single cultivar. Based on these results and on historical records, some hypotheses are proposed to explain the origin of sweet potatoes cultivated in Chile. This revised version was published online in July 2006 with corrections to the Cover Date.     

甘薯块根硬度与干物质含量的相关性

分别采用硬度测定法和烘干法,测试129份甘薯品种(系)块根不同部位的硬度值与干物质含量,构建甘薯各部位硬度与干物质含量的线性回归方程,以探讨甘薯硬度与干物质含量的关系,以及甘薯硬度与干物质含量分级标准。结果表明,129份甘薯材料的块根干物质含量与硬度均可划分为服从正态分布的5级,其平均分布频率为10.00%、19.12%、40.88%、20.88%和9.12%;甘薯不同部位硬度之间存在显著差异;其硬度值表现为径向切割心部径向切割中部轴向切割尾部轴向切割头部轴向切割心部轴向切割中部;甘薯硬度与干物质含量呈极显著正相关,以径向切割心部与径向切割中部硬度的平均值建立甘薯干物质含量与硬度间的回归方程为y=0.6743x+3.6184(20≤x≤60,R2=0.712192);用该回归方程验证20个样品集,计算所得干物质含量值与测定值相对误差为0.2%,表明该回归方程可用于准确、快速、低消耗测定甘薯块根干物质含量,指导甘薯育种实践。     

北方区试中甘薯农艺和品质性状的相关性及主成分分析

为了了解影响甘薯产量和品质各性状间的相关性及主次关系,应用多元统计方法,分析了北方区试中农艺和品质性状的相关性及主成分关系。结果表明：在对农艺性状与产量的相关性分析中,干率和淀粉率均与淀粉产量呈显著正相关,茎粗和大中薯率与薯干产量均呈显著正相关,大中薯率与鲜薯产量呈显著正相关;主成分分析表明,对淀粉产量和薯干产量贡献最高的主成分中的性状为大中薯率、茎粗和黑斑病抗病指数,贡献率分别为29.67%和30.13%;而对鲜薯产量影响最大的主成分中的性状为大中薯率和根腐病病情指数,贡献率为30.71%。通过对品质性状间的相关性分析表明,淀粉含量与还原糖含量、可溶性糖含量、甜度之间呈极显著负相关关系,粗蛋白含量与可溶性糖和还原糖之间存在弱负相关关系。而品质性状间的主成分分析表明,对甘薯品质贡献最大的主成分中的性状为还原糖、可溶性糖和蒸煮后的甜度,贡献率为59.12%;第二主成分为粗蛋白含量和蒸煮后粘度性状,贡献率为23.75%。总之,农艺性状对影响不同产量目标形成的侧重点不同,甜、糯性状是影响甘薯品质的主要性状。     

The Response of Sweet Potato (Ipomoea batatas Lam.) to Inter- and Relay-cropping with Maize (Zea mays L.)

Four sweet potato cultivars were inter- and relay-cropped with maize at two locations in Peru. Increasing interspecific competition drastically reduced tuber yields of all cultivars; fewer tubers m ⁻² were produced and no tolerant genotype was identified. Likewise the mean tuber weight declined linearly for two cultivars when competition became severe. Shoot development was less affected. Under intense competition the plant top was favoured in assimilate partitioning to the detriment of tuber formation. Overall reduction in assimilate production due to mixed cropping was the major cause of yield loss. Various intercropping combinations were found with the same productivity but distinct proportions of the component crops (sweet potato + maize). Land equivalent ratio (LER) exceeded sole crop productivity only for the combinations with the highest maize yields. Biomass production was clearly increased by intercropping but there was no increment in marketable yields. Relay-cropping reduced tuber and maize yields and had the lowest productivity of all combinations tested.     

甘薯胚性细胞悬浮培养系的建立

地甘薯胚性细胞悬浮增减系的进行了研究。将１２个基因的长约０．５ｍｍ的茎尖培养在含有０．２ｍｇ／Ｌ或２．０ｍｇ／Ｌ２，４－Ｄ的ＭＳ培养基上，形成了胚性愈伤组织。胚性愈伤组织的形成率因基因型和２，４－Ｄ深度不同而很大差异，为０－７５．７％。一方面，将胚性愈伤组织继续增减在含有２，４－Ｄ的ＭＳ培养基上，它们形成了处于各发育时期的体细胞胚。将具有体细胞胚的胚性愈伤组织转移到ＭＳ基本培养基上，体细胞胚发育成