增强的UV-B辐射对水稻光合作用的影响

以粳稻品种沈农6014及沈农265为试验材料,采用盆栽方法,研究UV-B辐射增强对水稻光合作用的影响.试验设3个处理,即自然光照(TCK)处理、紫外辐射增强5%(T1)和增强L0%(T2)处理.结果表明,增强的UV-B辐射能够降低水稻的叶绿素a、叶绿素b、叶绿素a/b、净光合速率、光舍有效辐射利用量及可溶性蛋白含量,提高类胡萝卜素含量.对可溶性糖含量的影响为先增大后减少.     

UV-B辐射增强及CO_2浓度升高对水稻产量及品质的影响

于2008年以日本粳稻品种Sasanishiki为研究材料,利用开放式气候室,以正常CO2浓度350±50mg/L和自然光照处理为对照,设置UV-B 14.7k J/(m2·d)、CO2700±50mg/L及CO2+UV-B复合3个处理,研究了CO2浓度升高及UV-B辐射增强对该品种水稻糙米产量及品质的影响。结果表明:(1)水稻单株产量CO2浓度升高处理增加21.78%,而千粒重、单株穗数、穗粒数及结实率无显著变化。结实率与单株产量UV-B辐射增强及复合处理分别降低6.44%、6.13%、14.89%、14.79%。千粒重复合处理降低5.28%。(2)CO2浓度升高及复合处理导致糙米的完整粒比率下降(29.54%~42.18%),断裂粒(29.73%~103.25%)和未成熟粒(30.71%~176.36%)的比率增加。UV-B胁迫下,未成熟粒比率增加幅度均小于CO2单独处理及复合处理。(3)UV-B辐射增强、CO2浓度升高及复合处理均显著增加脂肪酸含量(32.6%~76.29%)和蛋白质含量(5.3%~28.0%),而对水分和支链淀粉含量没有影响。综上所述,UV-B辐射增强显著抑制了水稻产量;CO2浓度升高显著增加水稻产量,但在本试验设计范围内,CO2浓度升高并未缓解UV-B辐射增强的抑制效应;UV-B辐射增强、CO2浓度升高及二者复合处理均显著改变了该品种稻米的营养品质。     

UV-B辐射增强对喜树叶片色素含量和形态结构的影响

笔者通过盆栽试验,以自然辐射为对照,研究人工增强UV-B辐射下（5.0 μW/cm2）喜树叶片中光合色素、类黄酮化合物含量及叶片形态结构的变化。试验结果表明：（1）UV-B辐射增强导致喜树叶片总叶绿素含量、叶绿素a与叶绿素b的比值（Chla/Chlb）及类黄酮类化合物含量上升,并随后呈下降趋势,而类胡萝卜素含量持续升高;（2）UV-B辐射增强导致叶形呈不对称状,色素分布异常,并伴有上表皮增厚、栅栏组织细胞增多、叶绿体扭曲的变化;（3）UV-B辐射增强使喜树叶片上表皮蜡质层增厚,表皮毛和腺毛数量增多,腺毛变短而粗;下表皮气孔被蜡质覆盖,开度变小。因此,增强UV-B辐射处理后,喜树幼苗体内的防御系统启动,叶片形态发生适应性变化,但最终喜树叶片细胞膜系统仍受到伤害并出现膜脂过氧化。     

干旱区UV-B辐射增强对棉花生理、品质和产量的影响

通过人工增加对棉花UV-B辐射,研究在大田栽培和自然光照条件下人工模拟紫外辐射(UV-B,280-320nm)增加对棉花生理、品质和产量的影响。实验设置4个处理,每个处理的辐射剂量分别为0W·m-2(R0)、0.5W·m-2(R1)、1W·m-2(R2)、1.5W·m-2(R3)。测定棉花不同处理时期的叶绿素含量、可溶性蛋白质含量、脯氨酸(Pro)含量以及棉花的品质和产量。结果表明,随着UV-B辐射增强,棉花叶片叶绿素a、叶绿素b和总叶绿素含量以及可溶性蛋白质含量呈现先升后降的趋势,Pro相对含量增加,棉花产量和品质均明显降低。因此,UV-B辐射增强对棉花造成了一定程度的伤害。当辐射剂量超过棉花植株体内一定的阈值之后,伤害程度就越大,最终导致棉花产量下降,品质降低。     

低剂量60Co-γ辐射种子预处理对黑麦草紫外线B辐射伤害的保护作用

将经过低剂量60Co-γ辐射(0、5、10、20和30 Gy)种子预处理的黑麦草(Lolium perenne L.,品种‘Victorian’)幼苗在室内控制条件下进行紫外线B辐射[6.5 kJ/(m2.d)]处理。UV-B辐射导致严重的苗体伤害,比如衰老加快、生长抑制和膜脂过氧化,然而低剂量的60Co-γ辐射(LDG)种子预处理显著降低了苗体UV-B伤害,尤其是20和30 Gy(1 Gy=1 J/kg)。抗坏血酸和UV吸收化合物在LDG处理下显著升高,UV化合物进一步被UV-B辐射提高了2倍以上;30 Gy处理的叶片光合色素一直维持在较高的水平。因此我们推测植株UV-B耐性在LDG处理下的提高至少部分归咎于抗坏血酸和UV化合物含量的提高,以及保持高水平光合色素的能力。本研究还探讨了LDG和UV-B复合处理的耐性机制。     

外源褪黑素对UV-B辐射下马铃薯光合、荧光特性的影响

增强UV-B辐射会对植物造成损伤,褪黑素可以增强植物抗逆性。通过不同浓度褪黑素处理不同UV-B辐射下的马铃薯幼苗,测定其株高、光合参数(Pn、Gs、Ci、Tr)、荧光参数(Fv/Fm、ETR、qP、NPQ)、1,5-二磷酸核酮糖羧化酶(Rubisco)和磷酸烯醇式丙酮酸羧化酶(PEPC),分析褪黑素对UV-B辐射下马铃薯光合、荧光特性的影响,为揭示褪黑素对UV-B辐射下马铃薯植株的防御机制提供科学依据。以马铃薯品种合作88为试验材料,采用自然光照(CK)和3个增强的UV-B辐射(2.5,5.0,7.5 KJ/(m~2·d)),在4种光照条件下分别设置0,25,50,100,150,200μmol/L的褪黑素浓度处理马铃薯幼苗。马铃薯受到增强UV-B辐射后株高、1,5-二磷酸核酮糖羧化酶、磷酸烯醇式丙酮酸羧化酶、光合参数、荧光参数(除NPQ)都降低,施加褪黑素后有所升高。褪黑素能提高马铃薯对UV-B辐射的抗逆性,使其植株增高,光合能力增强,但过高的褪黑素浓度也会对植物造成一定的损伤。     

两种栽培荞麦对日光UV-B辐射的响应

两种荞麦(甜荞和苦荞)栽培在不同紫外线B(UV-B)辐射[减弱(-UVB)、近充足(NA,Near-abient)、增强(+UVB)]保护小区内,以研究当前和未来增强UV-B辐射对其生长、发育、产量、生物量和卢丁含量等的影响。结果表明,不仅未来增强UV-B辐射而且当前高原条件下的UV-B辐射显著抑制了荞麦的生长、降低了产量和生物量积累,但促进了荞麦发育使其开花期提前。另一方面,叶片卢丁和UV吸收化合物在NA和增强UV-B辐射下显著增加,而多酚氧化酶在UV-B辐射下大幅度提高。两种栽培荞麦对UV-B辐射非常敏感,在高紫外辐射地区或未来增强UV-B辐射条件下荞麦生产除应考虑到高产外,还应该考虑到荞麦对紫外线辐射的耐性。     

UV-B辐射增强对甘薯光合特性和紫外吸收物质的影响

为探索UV-B辐射增强对甘薯光合特性和紫外吸收物质含量的影响,以徽薯为试验材料,以自然光为对照,设2个UV-B辐射增强处理[在自然光基础上增加UV-B辐射3.6和7.2kJ/(m ²·d)分别编号为T1、T2处理],测定不同辐射强度下光合色素含量、光合作用参数和紫外吸收物质含量。结果表明：叶绿素a（Chla）、叶绿素b（Chlb）、类胡萝卜素（Car）和叶绿素a/b的值均随UV-B辐射强度的增加而降低,且Chla、Chlb和Car分别在处理第100、80和40天时对辐射变化最敏感;净光合速率（P_n）显著下降,气孔导度（G_s）降低,胞间CO₂浓度（C_i）和蒸腾速率（T_r）无明显变化规律,气孔限制值（L_s）的变化趋势与C_i相反;紫外吸收物质显著升高,呈CK相似文献   

硅营养对UV-B辐射条件下水稻酚类代谢的影响

本研究在不同硅营养条件下,探讨了UV-B辐射增强对两个供试水稻品种(Lemont和Dular)硅营养特性和酚代谢物质的影响。结果表明：(1)在缺硅营养和UV-B辐射胁迫下,Lemont的硅营养吸收能力和生理利用率都比Dular强。（2）不同硅营养条件下,UV-B辐射胁迫促使Lemont叶片的PAL、PPO、 POD、CAT活性增强,总酚、类黄酮和绿原酸含量升高,而可溶性蛋白质含量降低;上述指标在Dular叶片中也表现出相同的变化趋势。但在缺硅营养和UV-B辐射共同胁迫下,Lemont表现出较强的酚类合成能力。（3）硅营养有利于水稻酚类代谢物质的积累,以减少UV-B辐射的伤害。综上所述,Lemont与Dular之间硅营养特性的不同,可能是引起两个供试水稻的酚类代谢差异,从而表现出对UV-B辐射抗性不同的原因之一。     

烤烟δ13C值及碳氮代谢对增强UV-B辐射的响应

为研究增强UV-B辐射对烤烟叶位δ13C值、碳氮代谢及烟叶化学成分的影响,以烤烟品种‘K326’为试验材料,在云南省玉溪市红塔区赵桅试验基地(24°18′N,102°29′E,海拔1645 m)进行大田增强UVB辐射强度试验。研究了增强不同UV-B辐射强度处理对烤烟13和16叶位烟叶δ13C值、碳氮代谢和化学成分的影响。结果表明:13叶位不同处理δ13C值的变化范围在-26.77‰~-25.16‰,16叶位δ13C值变化范围在-26.00‰~-24.99‰。自然环境条件下UV-B辐射实测值和烟叶δ13C值变化趋势,表现为随UV-B辐射增强烟叶δ13C值减小。其中T1总碳含量明显减小,其余处理总碳含量变化不大,说明适当增强的UV-B辐射对烟叶的总碳含量积累有利。而全氮含量表现为随紫外辐射的增强,其含量增加的趋势,尤以T2处理全氮含量增加最明显,即UV-B辐射与全氮呈显著正相关(P<0.05),与碳氮比呈显著负相关(P<0.05)。对2个叶位化学成分进行评分,得分情况为T2>T1>T3>CK,总体评价T2处理的化学成分协调性最好。相关分析结果亦表明,UV-B辐射与烟碱、全氮、钾呈正相关,与总糖、还原糖、氯呈负相关,其中与还原糖呈显著负相关(P<0.05)。     

Breeding for yield, in mixtures of common beans (Phaseolus vulgaris L.) and maize (Zea mays L.)

Summary Despite the growing industrialization, technification and transformation that is happening in the agriculture around the world, and despite that agricultural research has always concentrated its effort on sole crops, multiple cropping systems have historically been important for common bean production in tropical countries. The reasons for this fact, are economical and social, as well as biological. Bean breeders have always been questioned on their work, because the development of new varieties is usually done in sole crop, but the varieties are grown in either systems. This paper addresses a set of questions that are usually presented to the breeders, in light of the evidence obtained from many trials conducted in Brazil and in the U.S.A.: Will the genotypes bred for sole crop conditions, perform well when grown in intercrop; How different should a genotype be, for cultivation in intercropping compared to genotypes developed for sole crop conditions; Is there a need for special breeding programs for intercropping and How could a breeding program focus the question of multiple (associated) cropping?     

On bacterial wilt of alfalfa (Medicago sativa L.) caused by Corynebacterium insidiosum (McCull.) Jensen,in Italy

Bacterial wilt of alfalfa (Medicago sativa L.) caused by Corynebacterium insidiosum (McCull) Jensen was unknown in Italy until 1957. The authors established in that year in the province of Bologna this dangerous disease in 2–3 year-old stands of alfalfa which appeared uniformly and extensively thinned.They started a breeding programme with the use of bacterial wilt resistant material from the U.S.A., while also studies on methods of testing for resistance under Italian conditions are in progress.     

The domestication and improvement of cowpeas (Vigna unguiculata (L.) Walp.)

Summary Physiological and morphological characteristics of the two wild and three domesticated subspecies of cowpeas are compared. The wild accessions are alike in having small, hard seeds borne in dehiscent pods, but differ in other characteristics. We suggest that the wild subsp. dekindtiana, from the seasonally-arid tropics, is more likely to have been the progenitor of modern cowpeas than the other wild subspecies (subsp. mensensis), but that subsp. dekindtiana was first cultivated in the humid tropics where its pods are slow to dehisce. Domestication has been associated with changes in the structure of pod valves and seed coats which reduce pod dehiscence and seed hardness. Pods and seeds have increased in size, mainly by increases in the rate of dry weight accumulation, and their increase has been only partly paralleled by increase in the area of subtending leaves. There has been no increase in the maximum photosynthetic rate of leaves, but the duration of their photosynthetic activity has increased. Domesticates are less sensitive than are wild plants to some environmental controls, such as in the response of germination to temperature, but in their flowering responses to daylength both wild and cultivated forms retain sensitivity under conditions where this is of adaptive value.     

Linkage studies in rice (Oryza sativa,L.)

Linkage studies in rice up to 1959 have been briefly reviewed with a special reference to the work carried out at the Central Rice Research Institute, Cuttack, India. The crossover values for several genes have been furnished. Instances have been cited wherein two or more genes appear to be involved in determining the expression of anthocyanin pigmentation in different plant parts.

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Samenvatting Een overzicht wordt gegeven van de literatuur tot en met 1959 over de koppeling van genen bij rijst, in het bijzonder het koppelingsonderzoek uitgevoerd door het Central Rice Research Institute, Cuttack, India.De crossover-waarden voor vele genen worden vermeld. Enkele gevallen zijn genoemd waarbij 2 of meer genen een pleiotrope werking hebben bij de vorming van anthocyaan in verschillende delen van de plant.

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Paper read in the meeting of the Working Party on Rice Production and Protection of the International Rice Commission, held in Ceylon during December, 1959.     

Inheritance of seed size in cowpea (Vigna unguiculata (L.) Walp.)

Summary The inheritance of seed weight in cowpea was examined in a field planting of the parents, reciprocal F₁s, F₂s and backcrosses to both parents of a cross between TVu 1977-OD (small seeded) and ACC 70002 (large).Seed weight was inherited quantitatively and small seed was partially domiminant to large seed size. Gene action was predominantly additive but dominance and additive × additive epistatic effects were also significant.Broad and narrow sense heritabilities were 85.1±5.3% and 75.4±18.6% respectively. The minimum number of loci involved in the inheritance of seed size was eight, and each gene pair contributed up to 1.02 g increase to seed weight. The estimate of genetic advance from F₂ to F₃ generations with 5% selection intensity was 3.58 g.International Institute of Tropical Agriculture, Semi-Arid Food Grain Research and Development Project/National Cowpea Improvement Program, B.P. 1783, Ouagadougou, Upper Volta.Department of Primary Industries, Hermitage Research Station, Warwick 4370, Queensland, Australia.International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), ICRISAT Center, Patancheru, P.O. 502 324, A.P., India.     

Leaf scorch (Kabatiella caulivora (Kirch.) Kirk.) of subterranean clover (Trifolium subterraneum L.): Influence of host cultivar,growth stage and pathogen isolates on the disease severity

Summary Interaction of six isolates of Kabatiella caulivora (545, 547, 2212, BNL, BDG and KLN) collected from different geographical regions of Western Australia and Victoria with six cultivars (Clare, Daliak, Enfield, Guildford D, Karridale and Woogenellup) of subterranean clover was studied at seedling (2-week old) and adult-plant (12-week old) stages. Seedling response measured as percentage of diseased plants showed cultivar Daliak to be immune to all isolates, while the remaining cultivar x isolate combinations showed differing degrees of susceptibility.The adult-plant response, measured as percentage of petioles affected per plant, showed that all the cultivars were susceptible to varying degrees to all the isolates, with Daliak being the most resistant cultivar.Analysis of variance of both seedling and adult-plant resistance showed significant (P<0.05) effects due to cultivars, isolates and their interaction. The magnitude of variance due to the isolates was substantially reduced when measured as adult-plant response. Leaf scorch severity was clearly influenced by cultivar and its developmental stage, and by isolate of the pathogen.     

Genetics,genomics and breeding of groundnut (Arachis hypogaea L.)

Groundnut is an important food and oil crop in the semiarid tropics, contributing to household food consumption and cash income. In Asia and Africa, yields are low attributed to various production constraints. This review paper highlights advances in genetics, genomics and breeding to improve the productivity of groundnut. Genetic studies concerning inheritance, genetic variability and heritability, combining ability and trait correlations have provided a better understanding of the crop's genetics to develop appropriate breeding strategies for target traits. Several improved lines and sources of variability have been identified or developed for various economically important traits through conventional breeding. Significant advances have also been made in groundnut genomics including genome sequencing, marker development and genetic and trait mapping. These advances have led to a better understanding of the groundnut genome, discovery of genes/variants for traits of interest and integration of marker‐assisted breeding for selected traits. The integration of genomic tools into the breeding process accompanied with increased precision of yield trialing and phenotyping will increase the efficiency and enhance the genetic gain for release of improved groundnut varieties.     

Intra species variation in Atylosia scarabaeoides (L.) Benth., a wild relative of pigeonpea (Cajanus cajan (L.) Millsp.)

Summary Atylosia scarabaeoides (L.) Benth., a wild relative of pigeonpea, possesses several useful genes which can be utilized for pigeonpea improvement. In the present study, 33 accessions of A. scarabaeoides were evaluated at ICRISAT Center during the 1987 rainy season for variation in some useful traits to identify parents for inter-generic hybridization. A large variation was observed for leaf components, seed size, pod length, seeds/pod, days to flowering, seed protein, sulphur amino acids, resistance to cyst nematode, phytophthora blight, sterility mosaic, fusarium wilt, pod borer, pod fly, and pod wasp. Only four accessions were found to have more than 28% protein content. Methionine and cystine contents were marginally higher than in pigeonpea but the variation was not large enough to utilize them in the breeding program. In A. scarabaeoides. accessions resistant to fusarium wilt, phytophthora blight, sterility mosaic, and cyst nematode were detected. Compared to pigeonpea, the A. scarabaeoides accessions were less susceptible to lepidopteran borer and were immune to pod fly damage. Accessions ICPW 89 and ICPW 111 in short- (100–120 days), and ICPW 94 and ICPW 118 in medium-duration (140–180 days) were identified as potential parents for use in inter-generic hybridization.ICRISAT Journal Article No. 967     

Multifactor inheritance of seedcoat colour in greengram (Vigna Radiata (L.) Wilczek.)

Summary Seedcoat colour in greengram (Vigna radiata (L.) Wilczek.) is a useful marker for genetic studies and varietal identification. Its mode of inheritance was examined in five crosses among nine parents which differed for seedcoat colour. Four of the parents had sap green seedcoat colour while the others had raw sienna, brownish green, densely black spotted, black and greenish yellow seedcoat colour, respectively. At the F₂ generation, no more than 20 different colour classes were observed. The segregation in F₃ and backcross generations indicated that at least five major genes were involved in seedcoat colour inheritance. Sap green seemed to be dominant over raw sienna. The segregation ratios further indicated the role of non-allelic gene interactions (epistasis) in inheritance of seedcoat colour. Gene symbols were assigned to each colour and genotypes to each parent.     

Adaptation and competition in mixtures of cowpea (Vigna unguiculata (L.) Walp.)

Summary Six pure lines and four mixtures were grown in six environments throughout lowland Papua New Guinea. There were no significant transgressive increases in the grain yield of mixtures above their pure line components, and mixture yields were adequately predicted by the mean of components. In yield stability it was found that the individual buffering of pure lines was of more importance than population buffering, and that the magnitude of population buffering varied with the particular combination of components. Competitive effects in all the mixtures were of the compensating type. Dramatic changes in mixture composition resulting from natural selection precluded their use in local agriculture. The outcome of competition in mixtures was strongly influenced by the growing environment, such that selective index was correlated to general fertility.