Effect of temperature on seed and fruit development in three mango (Mangifera indica L.) cultivars

The effect of diurnal maximum/minimum (20/10 or 25/15 °C) temperatures on seed and fruit development of ‘Irwin’, ‘Kensington’ and ‘Nam Dok Mai’ mangoes (Mangifera indica L.) was studied in a controlled-environment glasshouse. Exposure to low temperatures (20/10 °C day/night) 3 days after hand pollination significantly increased the percentage of stenospermocarpic fruit (nubbins), in which embryos were aborted at some stage during early fruit development. There were significant differences between cultivars in the percentage of nubbins produced out of the total fruit set following overnight exposure to 10 °C with 21% for ‘Nam Dok Mai’, 11% for ‘Kensington’ and 3% for ‘Irwin’. At 45 days after pollination, nubbin fruits were much smaller in size and weighed ca. 50% less than normal fruits. The lower percentage of nubbin fruits in ‘Irwin’ implies a greater adaptation to cool temperatures by this cultivar during fruit set and early embryo development.     

Graft union formation in mango (Mangifera indica L.)

Summary

Graft union formation in mango (Mangifera indica L.) was studied using light microscopy. The initial wound response was resin secretion which contributed mainly to the initial adhesion of the graft partners. Early callus formation occurred mainly from the rootstock with cells produced in definite rows, often in fan-like array. Parenchyma cells at the cortex, pith, xylem and phloem rays were all involved in callus formation. The establishment of the cambial bridge between the stock and scion was followed by the formation of a protective layer, the periderm across the callus edges.     

Effect of temperature on pollen germination and pollen tube growth of four cultivars of mango (Mangifera indica L.)

Summary

The effect of a constant (10, 15, 20 or 25°C) or a diurnal maximum/minimum (15/5, 20/10, 25/15 or 30/20°C) incubation temperature on in vitro pollen germination and pollen tube growth in the pistils of two poly-embryonic (‘Kensington’ and ‘Nam Dok Mai’), and two mono-embryonic (‘Irwin’ and ‘Sensation’) mango cultivars was studied. In in vitro experiments where pollen was incubated in a liquid germination medium for 24 h in darkness, little difference was found between pollen germination of mono- and poly-embryonic cultivars. Averaged over the four cultivars, 53.9% of pollen germinated at 10°C, this increased to 76.2% when the incubation temperature was increased to 15°C, thereafter up to 25°C the percentage germination remained stable but germination decreased slightly to 68.2% at 30°C. Similarly, there was no difference in percent germination between cultivars when pollen was incubated under diurnal temperature regimes. Mean pollen germination of all four cultivars was 52.3% at 15/5°C and pollen germination increased by 10% when the temperature was raised to 30/20°C. When self-pollinated flowers were incubated for 24 h on a semi-solid agar medium at 10°C, pollen tube growth of the four cultivars was retarded and no pollen tubes reached the ovaries. As the temperature was increased from 15 to 25°C, the mean number of pollen tubes in ovaries increased from 0.04 to 0.25. At 30°C, the mean number of pollen tubes that entered ovaries decreased to 0.04. After incubation under diurnal temperature regimes, the mean number of pollen tubes in ovaries of all four cultivars at 15/5°C was 0.23 and increased to 0.42 when the temperature increased to 30/20°C. At each incubation temperature, there were significant differences in pollen tube growth between cultivars, but there were no differences between the temperature response of pollen from mono- and poly-embryonic cultivars.     

Effect of temperature on inflorescence development and sex expression of mono- and poly-embryonic mango (Mangifera indica L.) cultivars

Summary

The effect of temperature on inflorescence development and sex expression in two mono-embryonic (`Irwin' and `Sensation'), and two poly-embryonic (`Nam Dok Mai' and `Kensington') mango cultivars was studied. Trees were subjected to natural winter temperatures to induce flowering prior to transfer into controlled environment glasshouse rooms under day/night temperature regimes of 15/5, 20/10, 25/15 and 30/208C for 20 weeks. Inflorescence development did not progress when trees were held at 15/58C. Cooler temperatures (20/108C) delayed the start of anthesis (42.4.d) compared with trees grown at 25/158C (23.d) and 30/208C (16.1.d). At 20/108C, the delay in the start of anthesis was greatest for `Sensation' (55.5.d) and least for `Nam Dok Mai' (25.5.d) while at other temperatures there was little difference between cultivars. The distribution of hermaphrodite flowers within the inflorescence was independent of temperature with the highest percentage found in the apical half of the inflorescence. There was an inverse relationship between the length of the anthesis period and temperature, with anthesis occurring over 30.d at 20/108C and reducing to fewer than 10.d at 30/208C. Temperature also had an inverse effect on the total number of flowers per inflorescence with 619.6.6.108.0 (mean for all cultivars) at 20/108C decreasing to 431.3.6.80.5 at 30/208C.     

Effect of temperature on growth,dry matter production and starch accumulation in ten mango (Mangifera indica L.) cultivars

Summary

Ten mango cultivars of tropical and subtropical origin (Carabao, Kensington, Nam Dok Mai, Alphonso, Dashehari, Florigon, Glenn, Irwin, Haden and Sensation) were grafted onto cv. Kensington seedling rootstock and held at four day/night temperatures for 20 weeks (15/10°C, 20/15°C, 25/20°C and 30/25°C). Vegetative growth increased with increasing temperatures. All grew vegetatively at 25/20°C and 30/25°C. Cultivars which did not grow at 20/15°C were Carabao, Kensington and Dashehari. Cultivars Kensington, Nam Dok Mai, Alphonso, Florigon, Glenn, Irwin, Haden and Sensation produced flower panicles at 15/10°C. The rise in temperature increased the average number of growth flushes (in responsive cultivars) from 0.48 at 15/10°C to 3.21 at 30/25°C, and the number of leaves per growth flush (1.22 at 15/10°C to 13.63 at 30/25°C). Distribution of dry matter from new growth was mostly to the roots at the lowest temperature (95% at 15/10°C) and to the leaves (58%) at 30/25°C. The mean daily temperature for zero vegetative growth was calculated to be 15°C. Temperature and related growth activity also affected the concentration of starch in the woody tissue of rootstock trunks at the end of 20 weeks (15.9% starch at 15/10°C v. 4.8% starch at 30/25°C). ‘Irwin’ had the highest starch concentration at the two higher temperatures (twice that of any other cultivar at 30/25°C) while ‘Kensington’ the lowest starch level at 25/20°C, ca. 50% of most other cultivars.     

Further studies on graft-induced off-season flowering and fruiting in mango (Mangifera indica L.)

Summary

Defoliated shoots of cvs Alphonso, Dashehari, Totapari etc. (receptors), could be induced to flower within four weeks during the off-season by veneer grafting them to leafy shoots of the off-season flowering cv. Royal Special (donor) during the non-flowering season. Experiments on defoliating the donor and receptor shoots revealed the crucial dual role of the leaves in flowering. In the ‘floral cycle’, leaves from the donor promoted flowering, whereas leaves on the receptors, in the vegative phase, were inhibitory, and prevented graft-induction of the receptors. Thus, for graft induction, leafy donors and defoliation of receptors were essential. The inhibitory effect of the leaves on the receptors was localized and did not affect flowering of the donor shoots’ The similarity between these findings and those in the herbaceous, day-length sensitive species strengthens the view that flower formation is controlled in the same way in herbaceous and in woody perennial species. A minimum threshold of the floral stimulus appeared to be another requirement for an optimum flowering response. This was concluded from an experiment in which the leafy receptors were defoliated on different dates during the off-season flowering cycle. At the end of cycle, the defoliated receptors produced small panicles, and finally only vegetative shoots, probably indicating sub-threshold levels of the stimulus. Bud activity at the apex in the receptor was also an important pre-requisite for graft-induction. Some veneer-grafted scions which remained dormant during the flowering cycle of the donor and which sprouted much later after the completion of off-season flowering, ‘escaped’ the stimulus and invariably turned out to be vegetative. It is postulated that the cyclic synthesis of the floral stimulus in the leaves in an inductive cycle, and the gap between two such cycles, mainly decides the flowering behaviour of mango cultivars—biennial, annual and multiflowering. Two other requiremets are the absence of non-induced leaves and the synchronization of meristematic activity in the bud with the inductive cycle. Juvenile shoots from one to four year old seedlings could not be graft-induced—unlike the shoots from mature, six year old seeding trees. This juvenility effect continued into the second year when defoliation of the receptor shoots had no effect and failed to induce them to flower.     

Catecholase and cresolase activities and phenolic content in mango (Mangifera indica L.) at panicle initiation

Catecholase and cresolase (PPO) enzyme activities and phenolic content were measured in different mango cultivars at panicle initiation. Enzyme activity and phenolic content varied widely amongst eight cultivars, the maximum being in Bhadauran and minimum in Tommy Atkins. Floral malformation incidence was maximum (53.75%) in ‘Tommy Atkins’ and minimum in ‘Bhadauran’ (1.10%). A strong negative correlation was found between both the enzyme activity, phenolic content at panicle initiation and the incidence of floral malformation. Thus, PPO activity and level of phenolic compounds at panicle initiation may give a possible estimate of malformation incidence in mango.     

Morphology and anatomy of the burl disorder of mango (Mangifera indica L.) in India

Summary

Burl, typically manifest as a swelling of the trunk and lower branches, is a relatively unknown disorder of mango (Mangifera indica L.). We studied the incidence of the disorder in trees of each of three mango cultivars in India, and its effect on fruit yields over 2 years. Information was also collected on the relationship between the growth of the burl and the age of the trees, together with details of the anatomy of the affected tissues. ‘Langra’ had the highest incidence of the disorder (80.3% of 24 studied trees affected) and the largest burl (31.8 cm diameter), followed by ‘Chausa’ (17.5%; 16.4 cm), then ‘Gulab Jaman’(7.5%; 4.0 cm). Burl significantly reduced fruit yields in ‘Langra’ (121 kg tree^–1 in affected trees vs. 162 kg tree^–1 in normal trees), but not in ‘Chausa’ (110 vs. 129 kg tree^–1) or ‘Gulab Jaman’ (100 vs. 98 kg tree^–1). The sizes of the burls increased as the ages of the trees increased from 15 to 55 years, especially in ‘Langra’ and ‘Chausa’. No pathogens or insects were found to be associated with the affected tissues. The woody tissues in the burl lacked orientation and were not specifically aligned in a transverse, radial, or tangential direction. Further studies are warranted to determine the cause of this disorder and how it can affect fruit yields.     

杧果MiLCYB2基因启动子的克隆与序列分析

【目的】了解杧果Mi LCYB2基因的表达调控规律。【方法】应用染色体步移方法克隆了991 bp的Mi LCYB2基因启动子序列。【结果】用在线软件Plant CARE分析表明,该序列除含有启动子基本元件,如TATA-BOX、CAAT-BOX外,还含有ABA、GA、Auxin、SA、Me JA多种植物激素响应元件,以及参与生理周期调控、MYBHv1结合位点和光响应元件等一些其他的调控序列,推测Mi LCYB2基因的表达受多种植物激素、光照、生理周期、MYBHv1转录因子等的调控。【结论】杧果Mi LCYB2基因启动子的分离与序列分析为进一步探究杧果类胡萝卜素基因的调控机制提供了新的理论基础。     

Studies on the relationship between leaf number and area and fruit development in mango (Mangifera indica L.)

The optimum leaf number: fruit ratio in various mango cuitivars was sought by isolating individual fruits with known numbers of supporting leaves by shoot girdling. ¹⁴CO₂ feeding experiments showed a higher rate of carbon fixation in the leaves of girdled shoots than of control shoots but the translocation of ¹⁴C assimilates to the developing fruits on the girdled and control shoots was comparable. Starch accumulation in the leaves was reduced by shoot girdling. The stomatal resistance of the leaves of girdled shoots was comparable to that of leaves on control shoots. In all the cuitivars studied it was observed that 30 leaves, the maximum available on a shoot, could not support the growth of a single fruit to normal size. The results also show that fruit development depends not only on the current assimilates but also to a great extent on reserves. The utilization of reserve metabolites from vegetative organs during the ‘on’ year could be a contributing factor towards biennial and erratic bearing.     

广西杧果炭疽病菌种类的构成与分布

【目的】利用多基因手段结合形态学特征重新确定广西杧果炭疽病菌的分类地位,并统计分析各种类病菌的分布,了解广西杧果炭疽病菌的种类和优势群体,为进一步研究我国杧果炭疽菌及其病害的诊断、防控提供有力依据。【方法】从广西百色市、南宁市、钦州市等杧果产地采集杧果不同部位的炭疽病害样本,采用组织分离法进行分离,对所得分离物进行致病性测定,证明为杧果炭疽病菌。对病菌的ITS和ACT、GPDH、TUB2、CAL多基因位点进行扩增和测序,各基因序列按ITS、GPDH、ACT、TUB2、CAL的顺序相连接形成复合序列,采用MEGA 6.06软件以邻接法(neighbor-joining,NJ)构建系统发育树,结合病菌的形态特征鉴定其分类地位,并统计各种类病菌的总分离率及其在不同地区、植株不同部位的分离率。【结果】获得50株杧果炭疽病菌菌株,分别属于3个种:Colletotrichum asianum、C.fructicola、C.siamense,其中36株为C.asianum、12株为C.fructicola、2株为C.siamense。C.asianum、C.fructicola、C.siamense的总分离率分别为72%、24%、4%;C.asianum在所有检测地区、植株部位均能分离到,且分离率均最高,超过57.1%;C.fructicola能从所有检测地区、枝条以外的植株部位分离到,其中花梗上的分离率最高,为42.9%;C.siamense仅从百色市的果实上分离到,分离率为13.3%。【结论】广西杧果炭疽病菌主要有C.asianum、C.fructicola和C.siamense 3个种,均属于C.gloeosporioides复合种,其中C.asianum为优势种,C.fructicola是我国杧果炭疽病菌的新记录种;病菌的种类与地理来源、侵染部位无明显相关性。     

Water use and fruit yield of mango (Mangifera indica L.) grown in a subtropical Mediterranean climate

Mango (Mangifera indica L.) is one of the most important fruit crops in tropical and subtropical regions worldwide. On the coast of Granada and Malaga (SE Spain), irrigated subtropical fruit species have been introduced and cultivated on terraces with a considerable economic importance as the only European production region. The subtropical fruit production in this zone is possible with intensive irrigation on terraces, which are economically more profitable than traditional rainfed crops (almond and olive), which have been replaced or abandoned. A 2-year monitoring period was conducted using drainage lysimeters to determine the crop coefficients (Kc) and fruit yield in mango (Mangifera indica L. cv. Osteen) orchards. Also, some quality parameters such as titratable acidity, total soluble solids, and vitamin C were evaluated under these conditions. The averaged Kc values of mango trees varied within production cycle of 0.43, 0.67, and 0.63 at flowering, fruit set, and fruit growth, respectively. In this study, the fruit yield under full water requirements (100% ET_C) averaged 24.1 kg tree^?1, amounting to 21.2 kg ha^?1 mm^?1 in terms of water-use efficiency. The quality parameters of the mango fruits harvested in the study area were satisfactory. Thus, this study highlights the need to optimize the irrigation-water use according to actual mango requirements, thereby achieving more sustainable Mediterranean subtropical farming in orchard terraces.     

杧果种质果实品质性状多样性分析

 对中国热带农业科学院南亚热带作物研究所杧果种质资源圃40份杧果（Mangifera indica L.）种质的果实品质性状进行了连续3年的观测,采用方差分析、相关分析和主成分分析方法,从物理指标（果实形状、果实纵径、果实横径、果实侧径、单果质量、果核质量、可食率、果实纤维、果皮颜色）、化学指标（可溶性固形物、可滴定酸、还原糖和维生素C）和感官指标（风味和香气）3个方面对果实品质性状多样性进行了研究。结果表明：40份杧果种质的果实品质性状存在着极显著差异,具有丰富的多样性。Shannon-Weinner多样性指数（H′）在0.94 ~ 1.60之间,主成分分析表明果实品质性状变异的多向性。除可滴定酸和还原糖外,各种质品质特性年度间的差异不显著;一些果实品质性状间存在着显著或极显著的相关性。     

Root influence on shoot development in tea (Camellia sinensis (L.) O. Kuntze) following shoot pruning

The physiological interaction between the factors controlling the development of new shoots in pruned tea plants was investigated in an experiment using a widely cultivated TRI clone growing at low elevation in Sri Lanka. The functional importance during new shoot growth of root reserves, feeder roots and leaves and buds on unpruned branches (lung-shoots) is critically evaluated. A scheme for their interaction is presented, which highlights the need to maintain feeder roots alive during new shoot development, for which a large proportion of both reserve and current assimilates seem to be utilized. Mature leaves on lung-shoots, besides supplementing carbohydrate supply by current photosynthesis, may also serve to maintain the flow of metabolites from feeder roots to developing shoots and also function as ‘sinks’ for excess, toxic levels of root metabolites. Removing all mature leaves, as is done during ‘clean pruning’, leads to the depletion of reserves below the critical level for feeder root survival, resulting in death of feeder roots and failure of new buds to form shoots.     

部分杧果品种亲缘关系的ISSR分析

ISSR技术分析了38个杧果(Mangifera indica L. ) 品种的亲缘关系。从60条ISSR引物中筛选出10条重复性好、扩增带型清晰的引物, 共扩增出79条可重复性带, 多态性带比例为86.7%。扩增结果可区分38个品种中的37个(含红金龙或贵妃之一) 。各品种间遗传距离在0～0.682之间, 平均为0.393。UPGMA聚类将供试品种分成了5类。对分类结果进行了讨论。     

低温对杜果花粉母细胞减数分裂过程中核仁及染色体行为的影响

采用改良涂片法对低温和常温条件下卡亡果‘台农1号’和‘Irwin’花粉母细胞减数分裂过程进行观察,结果表明：卡亡果花粉母细胞胞质分裂为同时型。常温（25-30℃）条件下,花粉母细胞减数分裂过程较为正常,双线期染色体主要形成二价体,二价体构型以“V”、“O”、“Y”、“X”型、点状和棒状等形式存在,以点状、“V”和“O”型较多见,出现少量的单价体和多价体,其中台农1号为0．79％和4．76％,Irwin为0和3．57％;同时仅在少量中期Ⅱ和后期Ⅱ花粉母细胞中观察到落后染色体。低温（10—20℃）条件下,减数分裂过程中核仁的行为发生大量异常,微核仁的平均检出率高达22．88％,明显高于常温条件下的平均值（4．56％）;双线期单价体和多价体的发生频率有明显增加,其中台农1号中为8．82％和17．65％,Irwin中为14．52％和24．19％;减数分裂中期Ⅰ、Ⅱ及后期Ⅰ、Ⅱ均观察到落后染色体,其中台农1号的异常率为12．73％、5．63％、15．79％和4．76％,Irwin为11．11％、7．61％、9．52和6．38％。低温条件下减数分裂异常可能是造成雄性不育的重要原因。     

Effects of hot-water treatment and storage temperature on electrolyte leakage of mangoes (Mangifera indica Linn.)

Summary

Changes in electrolyte leakage were assessed on the skin, outer and inner mesocarp of hot-water treated mangoes at the end of 2, 5, 10 d during storage at 4, 9, and 138C respectively. Batches of fruit were subjected to hot-water treatments at the following time-temperature combinations: (1) untreated; (2) 36.58 for 75 min; (3) 36.58C for 60 min stepped up to 46.58C for 43 min, or 46.5C for 90 min (same heat units), and (4) 36.58C for 75 min plus 46.58C for 61 min or 46.58C for 120 min (same heat units). The time-temperature combinations were designed to ensure that the fruits received heat units equivalent to about 0, ¹/₂, 1 or 1¹/₃ of (468C for 90 min). Electrolyte leakage in fruit tissue was significantly highest in inner tissue and lowest in the fruit skin. The leakage increased in all fruit parts over time and with rise in storage temperature. Significant changes in electrolyte leakage were observed only in fruits stored at 138C. The skin of mangoes immersed in hot water at 46.58C for 120 min showed significantly higher electrolyte leakage compared with control and phased hot-water treatment (368C for 60 min + 46.58C for 43 min). Phased hot-water treatments showed lower electrolyte leakage compared with constant (one-stage) hot-water treatments and control. Fruits that received heat equivalent to 1 or 1¹ Ï /₃ of 46.58C for 90 min through phased hot water showed lower leakage compared with constant hot water immersion at the same heat units. Linear regression of natural logarithms of electrolyte leakage against calcium contents showed a strong negative correlation. Hot-water treatment at 46.58C for more than 60 min exacerbated the problem of fruit skin damage especially during storage at 138C.     

Sap volatile components in relation to susceptibility of anthracnose and Aspergillus rot of mangoes (Mangifera indica L.)

Sap burn injury and postharvest diseases are major causes of mango fruit quality deterioration, resulting in considerable postharvest losses in many countries. Susceptibility of selected cultivars of mango in Sri Lanka to sap burn injury and the incidence of anthracnose and Aspergillus rot of mango were examined in this study. Volatile components of non-aqueous (oil) phase were investigated using GC-MS, and artificial inoculation studies were carried out to assess disease resistance with Colletotrichum queesnlandicum (KC 820802) and Aspergillus niger (KC 820801). It was observed that the popular ‘Karuthakolumban’ and ‘Willard’ mangoes with high sap flow at harvest and high sap burn incidence were more susceptible to sap burn injury compared with ‘Chembaddan’ and ‘Ambalavi’ mangoes. Cultivar variations in susceptibility to Aspergillus rot of mangoes are reported for the first time in this study, where ‘Willard’ mangoes were more resistant to Aspergillus rot than other cultivars. The sap exudates of ‘Ambalavi’ and ‘Karuthakolumban’ mangoes were observed to contain the preformed antifungal compounds 5-pentadecyl resorcinol and 5-(Heptadeca-8,11- dienyl) benzene1,3-diol, with variety ‘Ambalavi’ showing a high resorcinol level. These cultivars were found to be resistant to anthracnose disease. These results suggest that presence of sap volatiles is cultivar dependent and could be used to identify cultivars resistant to postharvest diseases and sap burn.     

Effects of biennial cropping and controlled shoot density on yield performance and fruit quality in red raspberry (Rubus idaeus L.)

Effects of annual versus biennial cropping with varying shoot densities on plant structure, berry yield and quality were studied in ‘Glen Ample’ raspberry over a period of four seasons (two cropping years). In the vegetative phase, primocane height and internode length were larger in the annual than in the biennial cropping system. These parameters as well as Botrytis infestation increased with increasing shoot density. In both cropping years, berry yields per unit area were about 20% higher in the biennial cropping system, whereas yields per shoot were not significantly different in the two systems. In both cropping systems, yields per shoot strongly declined with increasing shoot density, while yields per metre row increased slightly. Regardless of cropping system, yields per metre row did not increase with increasing shoot density beyond eight shoots per metre. The concentrations of dry matter, soluble solids, titratable acidity and ascorbic acid as well as the intensity of juice colour all declined with increasing shoot density. We conclude that under controlled shoot density conditions, there is little scope for biennial yield increases that fully compensates for the lost crops every second year. However, the system greatly facilitates berry harvest and eases plant disease pressure.     

Physiological and biochemical changes with special reference to mangiferin and oxidative enzymes level in malformation resistant and susceptible cultivars of mango (Mangifera indica L.)

Changes in biophysical attributes, mangiferin and polyphenol oxidase (PPO), catalase and peroxidase activities in malformation resistant mango cultivar Elaichi were studied at various stages of flower development and compared with susceptible cvs. Amrapali, Beauty Mc-lin and Dashehari. Accumulation of mangiferin was maximum (96.0 and 108.0 mg g⁻¹ FW) in Elaichi prior to flower bud differentiation (September) and at full bloom (February), while these were minimum (59.0 and 74.0 mg g⁻¹ FW) in susceptible cv. Beauty Mc-lin. Mangiferin promoted vegetative growth and exhibited inhibitory role on the occurrence of malformation. It was also found that the resistant cultivar had highest activity of PPO as compared to susceptible ones. There was no significant difference in the enzymes catalase and peroxidase activity at early stage of flower differentiation but at flower bud burst stage the catalase activity was enhanced significantly in cv. Elaichi (25.28 unit min⁻¹ g⁻¹ FW) in comparison to Amrapali (16.20 unit min⁻¹ g⁻¹ FW), Beauty Mc-lin (18.39 unit min⁻¹ g⁻¹ FW) and Dashehari (17.50 unit min⁻¹ g⁻¹ FW). The resistant cultivar had high leaf temperature (30.30 °C) and diffusion resistance (476.14 m mol m⁻² s⁻¹) during the flowering but the rate of transpiration and relative humidity (RH) were high in susceptible cultivars. Results of the present study clearly indicate that level of mangiferin could be considered as a potential biochemical indicator for screening mango genotypes to malformation.