Eggplant Varieties Research Articles

Total Phenolic Concentration and Browning Susceptibility in a Collection of Different Varietal Types and Hybrids of Eggplant: Implications for Breeding for Higher Nutritional Quality and Reduced Browning

Phenolic compounds have numerous beneficial effects on human health. In consequence, the development of new varieties with higher content of phenolics is of interest for the improvement of the nutritional quality of eggplant (Solanum melongena L.). However, the oxidation of eggplant phenolics causes browning of the cut surfaces of the fruit and reduces its apparent quality. The authors investigated the relationship among, as well as the variation and heritability of, the content of phenolics, ascorbic acid, and soluble solids; pH; and the degree of browning and color difference of the cut surface of the fruit flesh in a collection of 69 eggplant varieties. These included landraces from different origins, commercial varieties, experimental hybrids, and four accessions of the related S. aethiopicum L. and S. macrocarpon L. species. Analyses of variance revealed significant differences among the materials studied for all traits considered. The concentration of phenolics in S. melongena spanned a threefold range, although the highest (1122 mg·kg−1) and lowest (134 mg·kg−1) concentrations of phenolics were found in S. macrocarpon and S. aethiopicum respectively. Concentrations of ascorbic acid were very low, a mean 27 times lower than those of phenolics, and soluble solids content ranged from 3.60% to 6.60% with a pH that ranged from 5.01 to 5.93. Commercial varieties had, as a mean, a 20% lower concentration of phenolics than landraces, as well as a lower degree of browning and color difference. Positive correlations existed between phenolic concentration and degree of browning (r = 0.388) and color difference (0.477), although only 15.1% and 22.8% of the total variation in degree of browning and color difference, respectively, could be attributed to variation in phenolics. Ascorbic acid, soluble solids content, and pH were not correlated to either degree of browning or color difference. The heritability was moderate for phenolic concentration (0.50) and high for degree of browning (0.71) and color difference (0.82). The information obtained indicates that there are opportunities for the development of new varieties with a high concentration of phenolics and low or moderate browning.

First report of Phytophthora capsici on cucurbits and peppers in British Columbia

Phytophthora capsici is a devastating pathogen of several commercial cucurbit and solanaceous crops. In August 2004, P. capsici was isolated and identified for the first time in British Columbia from an infected pumpkin (Cucurbita pepo var. medullosa) purchased from a market garden in Kelowna. Visual symptoms of fruit rot were also evident on several varieties of squash (Cucurbita spp.), pepper (Capsicum annuum), and eggplant (Solanum melongena var. esculentum) from the same area. Further characterization of the causal agent was needed to confirm its identification, pathogenicity, and ability to overwinter. Eight isolates obtained from infected pumpkin and from five different squash varieties grew on selective media for P. capsici. Single-spore isolates were produced from these cultures, and DNA was extracted from them. On the basis of sequence analysis, the eight isolates were P. capsici, differing by two or fewer nucleotides in the ribosomal spacer (internal transcribed spacer 2 (ITS2)) regions compared with previously identified strains. In pathogenicity studies, isolates 2256 and 2289, originally from butternut squash (Cucurbita moschata) and pumpkin, respectively, infected sweet pepper (Capsicum annuum var. frutescens) and butternut squash, killing pepper plants in 8 days. The isolates were less pathogenic on squash, according to the area under the disease progress curve, which was approximately six times higher in pepper than squash. Phytophthora capsici was recovered from both sweet pepper and butternut squash, as well as from infected zucchini (Cucurbita pepo var. melopepo) and watermelon (Citrullus lanatus) plants. Mating studies showed that isolates 2256 and 2289 were probably the A1 mating type because they produced oospores only if they were paired with the A2 tester strain obtained from the Centraalbureau voor Schimmelcultures culture collection. A hypothesis on how the disease developed and spread in British Columbia is presented.

Production and characterization of arboreous and fertile Solanum melongena + Solanum marginatum somatic hybrid plants

In crop plants the shift from being annuals to perennials may allow future agricultural systems requiring less energy inputs. The practicability of this was tested for Solanum melongena. Leaf protoplasts of S. melongena (2n = 2x = 24) and one of the related arborescent species Solanum marginatum (2n = 2x = 24) were electrofused and fertile somatic hybrids with arborescent habit regenerated. The magnetic cell sorter (MACS) technique was used for the selection of heterokaryons. The hybrid nature of 18 regenerated plants was assessed on the banding patterns generated by inter-simple sequence repeat PCR. When taken to maturity in the greenhouse, hybrids grew more vigorously compared to the parental species. Their morphological traits were intermediate between those of S. melongena and S. marginatum. Hybrids flowered and produced an average of 85% stainable viable pollen and fertile fruits. The somatic hybrids were maintained in the greenhouse for more than 3 years and continued to produce flowers developing into two types of fruits with plentiful seeds. Fruits were either striated green containing non-germinable seeds or yellow with fully germinable seeds. Their S(1) progenies showed common features with S(0) hybrids, including fertility and arborescent habit. Cytologically, somatic hybrids exhibited the expected chromosome number of 2n = 4x = 48, while chromosome pairing during microsporogenesis was associated with a low frequency of intergenomic pairing. It is concluded that an arborescent perennial species has been obtained by somatic hybridization. The usefulness of this species per se or in eggplant breeding will depend not only on the transmission of the arborescent habit to cultivated eggplant varieties, but also on the variability that should be created from backcrossing the S. melongena + S. marginatum hybrids to S. melongena.

Prehistory of the Notion of Circulating Nucleic Acids in Plasma/Serum (CNAPS)

In the late 50s and early 60s of the last century, a theoretical fight was taking place between Western and Russian scientists about the theory explaining the mechanism of evolution. According to neo-Darwinism, evolution was the result of hazard and necessity, that is, mutations arriving by chance favoring the survival of the fittest. For the Russian geneticists, acquired characteristics were the basis of evolution, that is, the environment modified the characteristics of the gene. One of the main experiments on which the Russian geneticists based their theory was the transmission of hereditary characteristics by a special technique of grafting between two varieties of plants-a mentor plant and a pupil plant. The pupil variety being entirely dependent on the development of the mentor plant its hereditary characteristics were modified accordingly. In the Western world these experiments were regarded with doubt. We were among the few who tried to repeat this kind of experiment. After three generations of grafting between two varieties of eggplant, we succeeded in obtaining hereditary modifications of the pupil plants, which acquired some of the characteristics of the mentor variety. The linkage between some hereditary characteristics of the mentor plant were broken, the segregation of the offspring was abnormal, dominant characteristics appearing in the offspring of a recessive plant. Rather than adopting the views of the Russian scientists about acquired characteristics, we suggested that DNA was circulating between the mentor and pupil plants and assumed that some nucleic acid molecules bearing genetic information could enter the somatic and reproductive cells of the pupil plant at a propitious moment and remain active.

Damage potential of the spider mite Tetranychus ludeni (Acari: Tetranychidae) on four varieties of eggplant

The damage potential of the spider mite Tetranychus ludeni Zacher was studied on 20 - 65-day-old seedlings of four eggplant Solanum melongena varieties: Madurai (MDU1), Coimbatore (CO1), Annamalai and Panruti at introduction levels of 2, 5, 10 and 15 mites/leaf. The average seedling mortality among varieties was lowest at the introduction level of two mites and maximum at the introduction level of 15 mites/leaf. The overall seedling mortality was 23% when the four levels of mite population were introduced on 20-day-old seedlings, and only 14% on 30-day-old seedlings. Among the different varieties, the MDU1 seedlings recorded higher mortality (1.6%) and Panruti the lowest (0.3%). The percentage losses in total plant height, number of leaves, number of flowers and fruits and fruit weight due to mite attack were highest (37 -50%) in MDU1 and lowest (7 - 11%) in the variety Panruti. The other two varieties CO1 and Annamalai were found to be intermediate between Panruti and MDU1. The inoculated mites at different levels multiplied greatly on the variety MDU1 followed by CO1, Annamalai and Panruti. The extent of damage was higher in 35-day-old plants, when mites were introduced on 35- and 65-day-old seedlings. Therefore, the variety Panruti is recommended for cultivation in the study area in view of its resistance to T. ludeni.

Comparisons of Grafted Biennial and Conventional Production Systems for Eggplant (Solanum melongena L.) Varieties in a Mediterranean Region of Turkey

Comparisons of Grafted Biennial and Conventional Production Systems for Eggplant (Solanum melongena L.) Varieties in a Mediterranean Region of Turkey

Response of eggplant varieties (Solanum melongena) to salinity in germination and seedling stages

Knowledge of salt tolerance in vegetable plants is necessary to increase productivity and profitability of crops irrigated with saline wastewaters. Eggplant (Solanum melongena) is moderately sensitive to salinity but more attention to salinity is required in the agricultural production of eggplant and its varieties. The objective of the present work was to investigate the response of some eggplant varieties to increasing salinity during the germination and seedling stages. Germination, length, and dry and fresh weight of radicle and hypocotyl, length and dry and fresh weight of root and shoot, number and area of leaves and sodium (Na+) and potassium (K+) ions in seedling leaves, were the assayed parameters. Increasing salt stress (0, 50, 100, and 150 mM NaCl) negatively affected growth and development of eggplant (S. melongena ’Kemer’, ‘Pala’, and ‘Aydin Siyahi') at the germination (percentage and period; length and fresh and dry weight of of radicle and hypcotyl) and seedling stages (length and fresh and dry weight of root, shoot, and whole plant; leaf number and area). When salt concentration increased, leaf Na+ content increased but K+ content and K+/Na+ ratio decreased. The response of varieties to salt was different depending on the growth stage, and salinity tolerance of cultivars increased at the later growth stages.

RAPD genetic homogeneity and high levels of bacterial wilt tolerance in Solanum torvum Sw. (Solanaceae) accessions from Reunion Island

Solanum torvum Sw. is a wild species closely related to eggplant ( S. melongena L.), native to India. Although invasive in some areas of introduction, this species is of particular interest as it has been identified as a potential source of resistance to bacterial wilt disease for cultivated susceptible Solanaceae species. Little is known about the levels of resistance and genetic diversity in this species, particularly in areas of introduction such as Reunion Island, where it is used as rootstock for grafting of susceptible tomato and eggplant varieties. Eight accessions were collected in diverse geographical locations on Reunion Island for further characterisation. Regardless of the accession, no wilted plants were detected four weeks after inoculation with three different Ralstonia solanacearum strains (phylotypes) from Reunion Island. Latent bacterial colonisation in symptomless plants was however demonstrated, mainly in roots and/or lower stem, showing that S. torvum can be considered as resistant to the race 1 biovar 1 strain, and tolerant to the race 1 biovar 3 and race 3 biovar 2 strains. The homogeneity between accessions regarding high bacterial wilt tolerance was confirmed by the genetic homogeneity (0% polymorphism) revealed using 168 RAPD markers. Similarly, only 1.2% polymorphism was revealed by the genetic study of seven accessions of S. torvum from Java used as reference. All the Java accessions, but one, were identical to Reunion accessions. The level of polymorphism between S. torvum accessions is assumed to be similar to the level of genetic differences existing between vegetatively propagated clones, therefore reduced to minimal mutational events. This reduced genetic variation is typical of what is expected for an autogamous species introduced on an island. Some differences in latent bacterial colonisation scores for some of the Reunion accessions were however noticed. These results are essential for further genetic and epigenetic studies on bacterial wilt resistance in S. torvum.

DEVELOPMENT OF RAPD-AFLP MAP OF EGGPLANT AND IMPROVEMENT OF TOLERANCE TO VERTICILLIUM WILT

Verticillium wilt is one of the most serious diseases in eggplant and one of the main goals of eggplant breeding is the achievement of Verticillium wilt tolerant hybrids. Solanum sodomeum L. has shown a mechanism of partial resistance against Verticillium wilt. Interspecific hybrids were obtained by using an accession of S. sodomeum from Sicily and the eggplant variety Buia. The results of the screenings for eggplant genotypes tolerant/resistant to Verticillium wilt by using backcrosses are reported. In a naturally infected field, from 1998 to 2001, the resistance to V. dahliae of backcrossed progenies was increased by about 60%. The interspecific hybrids were both selfed and backcrossed using different types of eggplant. An integrated linkage map of eggplant (Solanum melongena L.) has been obtained by using 48 plants of an F 2 population. Starting from a genetic RAPDs map with ∼ 100 markers mapped on 13 linkage groups, 4 AFLPs primer combinations were screened in order to improve the genetic map with the aim to achieve markers linked to Verticillium tolerance. Mendelian segregation of loci was verified by chi-square tests of the expected 3:1 and 1:1 ratios. Marker order was determined and all the data were combined to construct the most likely map. The integrated analysis of markers resulted in the construction of a map consisting of 273 loci and 12/13 linkage groups spanning 736 cM in a total. Linkage between different AFLP markers and the tolerance to Verticillium is discussed.

Biotechnology of eggplant

Eggplant ( Solanum melongena L.) is an important vegetable crop grown in various tropical and temperate parts of the world. There is a wide genetic diversity in the cultivated as well as the wild species of eggplant. Cultivated varieties of eggplant are susceptible to a wide array of pests and pathogens as well as to various abiotic stress conditions. In contrast, the majority of wild species are resistant to nearly all known pests and pathogens of eggplant and thereby are a source of desirable traits for crop improvement. Tissue culture protocols for organogenesis, somatic embryogenesis, anther culture and protoplast culture have been well established for the eggplant. Somatic hybridisation has also been attempted for transferring useful genes from wild species to the cultivated plants through protoplast fusion. However, the information on genetic engineering and molecular biology of eggplant is very limited. Transgenic eggplants for insect resistance, for the production of parthenocarpic fruits and abiotic stress tolerance have been accomplished. However, transgenics of eggplant are yet to be developed for improvement of other agronomic traits, including disease and pest resistance, and quality and shelf life of fruits. Molecular markers to complement traditional breeding programs are being developed for genome mapping of agronomic traits. The present review summarises efforts to improve eggplant genetics with an emphasis on the use of biotechnology to introgress genes from wild species into cultivated eggplant.

Grafting Compatibility of Cultivated Eggplant Varieties with Wild Solanum Species

Grafting Compatibility of Cultivated Eggplant Varieties with Wild Solanum Species

Nymphal Development and Survival of Macrolophus pygmaeus Rambur (Hemiptera: Miridae) on Two Eggplant Varieties as Affected by Temperature and Presence/Absence of Prey

Nymphal development of the predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) was investigated on two eggplant varieties, Bonica and Black Beauty, in an attempt to identify the possible role that plant variety plays in the development and survival of the predator and to determine whether these biological characteristics are influenced by temperature and prey. The development of nymphs was studied in the presence and absence of the prey, Myzus persicae (Sulzer), at 15, 20, 25, 30, and 35°C, 65 ± 5% RH, and 16:8 h (L:D) photoperiod. Significant differences in the periods of nymphal development were evident in the two varieties at 15°C when M. persicae was offered as prey, and at 15 and 30°C, when there was no prey, significantly shorter periods of development were recorded on Bonica than on Black Beauty. Mortality rates of the nymphs were similar in the presence of prey on both varieties but, in the absence of prey, higher mortality rates were recorded on Black Beauty than on Bonica. In both presence and absence of prey, at 35°C, a small number of nymphs reached adulthood on Bonica, whereas no nymphs did so on Black Beauty. Therefore, the less suitable variety, Black Beauty, had a significant effect on the development and survival of nymphs of this predator, mainly in the absence of prey and at lower and higher temperatures. It is concluded that the selection of a suitable variety for the development and survival of M. pygmaeus, particularly in the absence of prey, could improve the efficiency of a biological control program in which this predator is going to be used. This is of particular importance for its establishment and effectiveness at the beginning of the growing season when temperature is relatively low and the prey is absent or scarce, as well as in summer when temperatures are high enough (around 30°C or even higher).

Eggplant Variety Evaluation in West Central Florida

Eggplant (Solanum melongena) varieties and advanced breeding lines were evaluated in a full-bed polyethylene mulch system during Spring and Fall 1997. Yield and horticultural characteristics were assessed for eight entries in the spring and 13 in the fall. Spring: Highest U.S. Fancy yield from the two earliest harvests was 9.6 t·ha–1 from `Kiko' with a mean fruit weight of 0.64 kg and 1% of the total harvested fruit as cull quality. Highest U.S. Fancy yield from all five harvests was 31.2 t·ha–1 from PX 984 with a mean fruit weight of 0.50 kg and 16% cull fruit. Seasonal yields combining U.S. Fancy, U.S. No. 1, and U.S. No. 2 grades ranged from 11.4 t·ha–1 for `Special Hibush' to 47.3 t·ha–1 for `Neon', with four entries not significantly different than `Neon'. Fall: U.S. Fancy yields from the two earliest harvests ranged from 0.5 t·ha–1 for `Oria' to `Agora' (2.7 t·ha–1). Five other entries were not significantly different than `Agora' in early U.S. Fancy yield; `Orient Express', `No. 226', `Neon', `Ghostbuster', and `Vernal'. Greatest U.S. Fancy yield for all six harvests was produced by `Santana' with 25.7 t·ha–1, with a mean fruit weight of 0.45 kg and 14% cull fruit. Seasonal yields combining all grades ranged from 17.1 t·ha–1 for `Machiaw' to 41.2 t·ha–1 for `Santana', with six entries not significantly different than `Santana'.

Efficient shoot organogenesis of eggplant (Solanum melongena L.) induced by thidiazuron.

Morphogenesis from several explant types excised from in-vitro-grown plantlets of a Brazilian eggplant (Solanum melongena L.) variety (F-100) was evaluated in response to thidiazuron (TDZ). Leaves and cotyledons were found to be the most responsive explants. Optimal shoot bud induction rates (75-100 buds/explant) were achieved in the presence of 0.2 μM TDZ. Organogenic calli were transferred to growth regulator free MS medium before shoot excision. Rooting was induced on half-strength MS medium supplemented with 0.6 μM IAA.

OSU Douglas County Demonstration Farm

The demand for horticultural information from the OSU Extension Service is sought by both commercial fresh-market vegetable growers and noncommercial clients. Educational programs at the Demonstration Farm were designed to meet the needs of these two diverse groups. At the request of local growers, vegetable trials were established to evaluate the large number of new varieties that come onto the market every year. Since 1987, nearly 250 varieties of eggplant, melons, peppers, squash, sweet corn, and tomatoes have been evaluated for their adaptability to Douglas County's Mediterranean climate and growing conditions. Annual reports on the performance of the varieties are shared with county vegetable growers and Extension Agents throughout Oregon. Many of the vegetables for the trials are grown as bedding plants in the Demonstration Farm greenhouses. A greenhouse program was established to offer Master Gardeners the opportunity to participate in all of the cultural aspects of bedding plant production. This includes; seeding, transplanting, pinching, watering, and fertilizing. When planting season arrives, Master Gardeners help transplant the seedlings to the trial plots. An average of 40 Master Gardeners have participated in the greenhouse and trial program each year, since their inception in 1987. An average of 300 people attend the field days every summer to tour the vegetable trials. An outdoor gardening class, “Summer In The Garden,” is offered to the general public every summer. An average of five sessions are held in July and August on a variety of topics related to vegetable culture, pest control, and new varieties. The sessions are taught by the Horticulture Agent with the assistance of Master Gardeners. Attendance has averaged 25 students annually.

Multiplication of Pseudomonas solanacearum in Rhizosphere and Root Tissue of Susceptible and Resistant Varieties of Solanum melongena

AbstractThe population build‐up of Pseudomonas solanacearum in the rhizosphere, and root‐tissues of two egg plant varieties, susceptible and resistant, raised in infested soil was investigated at different stages of plant growth. There was no perceptible difference in the population build‐up of the pathogen in the non‐rhizosphere soils of both the susceptible and resistant plants. However, the soil 3 cm away from the tap root of the susceptible variety contained a higher population of the pathogen compared to the soil similarly drawn from the resistant plants. The pathogen population in the rhizosphere of the susceptible variety increased 1,000‐fold with increasing age of the plant and was highest at flowering. The rhizosphere of the resistant plant, showed only a 10‐fold increase in pathogen population. The trend was similar with the root tissue populations of the pathogen, but the differences in the root tissue populations of the resistant and susceptible plants were more pronounced. Considerable, buildup of the pathogen population in the susceptible variety was also seen in the above ground portions of the plants. Root extracts of the resistant variety had a marked inhibitory effect on the growth of the pathogen.

Untersuchungen zur Erfassung des latenten Befallsstadiums von Corynebacterium sepedonicum (Spieck. et Kotth.) Skapt. et Burkh. im Kartoffelgewebe

The causal agent of potato ring rot, Corynebacterium sepedonicum (Spieck. et Kotth.) Skapt. et Burkh., is well-known for its long incubation period. Often its inoculum concentration in the tissue of the host does not reach to induce distinct symptoms. Thus, during some years it can be distributed in potato material without to be detected. To inhibit the import and the seeding of potato tubers latently infected, special methods of detecting are necessary. In this paper, a sensitive technique for indicating the causal agent is proposed. It is suitable for analysing sprouts and tubers on potato ring rot. The material under test must be crushed and thereafter inoculated in young egg plant (Solanum melongena L.) for enrichment of the causal agent. Simultaneously, the samples homogenized are to analyse microscopically (Gram staining) and serologically (agargel-diffusion test from Ouchteelony). By suitable varieties of eggplant, for example “Frühviolette” and “Black Beauty”, very low cell concentration (less than 10 cells/ml) in plant tissue can be indicated. Following this test on latent infestation by C. sepedonicum, it is possible to use the tubers for further plant breeding studies. Der Erreger der Bakterienringfäule der Kartoffel, Corynebacterium sepedonicum (Spieck. et Kotth.) Skapt. et Burkh., ist für seine lange Inkubationszeit bekannt. Oft reicht seine Konzentration im Wirtsgewebe nicht aus, um eindeutige Symptome hervorzurufen. Dadurch kann er sich über Jahre hinaus unerkannt im Kartoffelanbau verbreiten. Um unter diesen Umständen einer möglichen Einschleppung vorzubeugen, sind spezifische Nachweismethoden notwendig. Es wird deshalb eine sehr empfindliche und sichere Nachweismethode für den Erreger vorgeschlagen. Sie ist sowohl für eine Kraut- als auch Knollenanalyse anwendbar. Für diesen Zweck werden die gezogenen Proben aufbereitet und über Testpflanzen (Solanum melongena L.) angereichert. Parallel hierzu erfolgt eine mikroskopisch-zytologische (Gram-Färbung) und serologische (Doppeldiffusions-Test nach Ouchterlony) Analyse. Mit geeigneten Eierfruchtsorten (z. B. „Frühviolette“, "Black Beauty") lassen sich sehr geringe Keimdichten (unter 10 Keime pro ml) im Pflanzengewebe nachweisen. Die mit Hilfe dieses Testes auf ihre latente Verseuchung mit C. sepedonicum untersuchten Knollen können anschließend züchterisch weiterverwendet werden.

Influence of irrigation rhythm and water supply on growth, water status and yield of egg-plant (Solanum melongena L.)

The responses of two egg-plant varieties to irrigation rhythm and water supply based on daily potential evapotranspiration were performed on St-Paul silt loam.

Low Temperature Growth in a Controlled Environment of Trifolium repens Plants from Northern Latitudes

With 27 eggplant varieties as test objects, this paper studied the effects of their leaf pubescent on the field population density of Polyphagotarsonemus latus, its injury index on eggplant leaf, and population growth rate. The results showed that the density and length of leaf pubescent differed with eggplant varieties. For the same variety, leaf pubescence had a higher density but a shorter length on reverse side than on obverse side. Among the test varieties, 7 resistant varieties had a significantly higher mean pubescence density than 6 susceptive varieties on their reverse side leaf. The higher the pubescence density on reverse side eggplant leaf, the less field population density of P. latus and the lower injury index of eggplant leaf, suggesting a positive correlation between the pubescence density on reverse side eggplant leaf and the resistance of eggplant to P. latus.

The Effect of Forage Structure and Availability on Food Intake, Biting Rate, Bite Size and Daily Eating Time of Reindeer

With lower-and higher heat-resistant varieties of eggplant (Solanum melongena L.) Heibei I and Heibei II as test materials, and by using Plant Efficiency Analyzer (PEA) from Hansatech, this paper measured the fast chlorophyll a fluorescence transient and its parameters. The results showed that PS II construction became more sensitive to heat stress when ambient temperature was higher than 40 degrees C. The F0 went up slowly, and Fv/Fm and deltaF/Fm' came down dramatically. Heibei II had a longer semi-attenuation temperature of Fv/Fm (T50) and deltaF/Fm' (t50) than Heibei I. Under strong heat stress (5 min at 48 degrees C or 20-30 min at 44 degrees C), the K-step in relation to the inactivation of oxygen-evolving complex appeared in fluorescence rise at about 700 micros, and the regular O-J-I-P transient was transformed to O-K-J-I-P one. The K-phase of Heibei I and Heibei II appeared when the treatment time was up to 20 and 30 minutes at 44 degrees C, respectively. In comparing with 35 degrees C heat treatment, the DI0/RC in the parameters of Strasser's specific energy fluxes model was increased by a great extent under 48 degrees C or more heat stress, reflecting a strong safeguard of energy dissipation to PS II. When the temperature of heat stress increased from 35 degrees C to 52 degrees C, the Fvi/Fv of PS II silent reaction centers of Heibei I and Heibei II increased remarkably.