Cultivation and possible domestication of feral and possibly wild yams (Dioscorea spp.) in Southwest Ethiopia: ethnobotanical and morphological evidence.

The far Southwest Ethiopians transplant wild plant species to their gardens. One of such plant is the Dioscorea that we studied to assess the knowledge of wild yam and process of domestication. The study links two types of evidence to obtain insight about the process of yam domestication. We analyze two data sets derived from (1) ethnobotanical survey using 231 semi-structured interviews; and (2) morphological study in 47 yam accessions. Our study revealed that domestication is still active in some villages. Knowledge of yam domestication was shared by 44% of the farmers' even by those that have never practiced its domestication. Farmers who can describe the trend of domestication and the morphotypes of domesticate represented 21 and 28%, respectively. Farmers who have recent transplants in their garden varied from 4% in Bench to 10% in Sheko. The domestication process described by the two ethnic groups is similar. The duration of domestication can take up to six years, but with most of the individuals, it only takes three to five years. By linking the two types of evidence, two evolutionary processes are distinguished: (1) populations of recent domesticate expressing a domestication syndrome possibly belongs to the wild D. abyssinica or D. praehensilis, and (2) plants of incipient domesticate that might be derived from volunteers or diverse types of hybrids. Each of these processes can lead to integration of wild genotypes into the cultivated gene pool, and hence, enhance genetic diversity of cultivated yams. The domestication practices of traditional farmers should thus be taken into account if yam conservation and improvement plans need to be established.

Organ- and Age-Specific Differences of Dioscorea polystachya Compounds Measured by UPLC-QTOF/MS.

Dioscorea polystachya, named Chinese yam, is widely cultivated as a functional food and natural medicine in China. There is currently little information about the chemical characteristics of Dioscorea polystachya in different organs (tuber cortex and tuber flesh) and at various ages. In this study, an ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was used to profile chemical compounds in Dioscorea polystachya. As a result, thirty-eight compounds were detected in yam tuber cortex and tuber flesh. More compounds were detected in yam tuber cortex than in tuber flesh. Compounds such as dehydroepiandrosterone, allantoin and flavonoids were selected as biomarker candidates. Dehydroepiandrosterone was found more abundant in tuber flesh, while allantoin and flavonoids showed higher levels in tuber cortex. Furthermore, the levels of dioscin, malvalic acid and sucrose differed significantly among age groups and were highest in the tubers at 2 years. While the levels of allantoin, adenosine and glutamine increased with the growing years and were highest at 4 years. Thus, 2-year old Dioscorea polystachya tubers could be harvested to prepare dioscin, malvalic acid and sucrose supplements. The 4-year-old Dioscorea polystachya tubers would be the best choice for obtaining a large amount of allantoin and adenosine in industrial production.

Agro-ecological suitability assessment of Chinese Medicinal Yam under future climate change.

Chinese Medicinal Yam (CMY) has been prescribed as medicinal food for thousand years in China by Traditional Chinese Medicine (TCM) practitioners. Its medical benefits include nourishing the stomach and spleen to improve digestion, replenishing lung and kidney, etc., according to the TCM literature. As living standard rises and public health awareness improves in recent years, the potential medicinal benefits of CMY have attracted increasing attention in China. It has been found that the observed climate change in last several decades, together with the change in economic structure, has driven significant shift in the pattern of the traditional CMY planting areas. To identify suitable planting area for CMY in the near future is critical for ensuring the quality and supply quantity of CMY, guiding the layout of CMY industry, and safeguarding the sustainable development of CMY resources for public health. In this study, we first collect 30-year records of CMY varieties and their corresponding phenology and agro-meteorological observations. We then consolidate these data and use them to enrich and update the eco-physiological parameters of CMY in the agro-ecological zone (AEZ) model. The updated CMY varieties and AEZ model are validated using the historical planting area and production under observed climate conditions. After the successful validation, we use the updated AEZ model to simulate the potential yield of CMY and identify the suitable planting regions under future climate projections in China. This study shows that regions with high ecological similarity to the genuine and core producing areas of CMY mainly distribute in eastern Henan, southeastern Hebei, and western Shandong. The climate suitability of these areas will be improved due to global warming in the next 50 years, and therefore, they will continue to be the most suitable CMY planting regions.

An integrated metabolomic strategy for the characterization of the effects of Chinese yam and its three active components on septic cardiomyopathy.

Chinese yam (CY), used as both a traditional Chinese medicine and a nutritious food, is an excellent candidate for treating septic cardiomyopathy (SCM). Adenosine, arbutin and allantoin are the major active components in the aqueous extract of CY. The aim of the present study was to interpret the roles of CY, adenosine, arbutin and allantoin in SCM treatment. Firstly, significant physiological indexes were examined to assess the model and treatment effects of CY, adenosine, arbutin and allantoin. Then, a metabolomic approach was utilized to reveal the metabolic disorders in SCM concerning the intervention of CY/adenosine/arbutin/allantoin. The integrated results demonstrated that adenosine, arbutin and allantoin are responsible for the efficacy of CY on SCM treatment by regulating amino acid, arachidonic acid, sphingolipid, glycerophospholipid and glycol metabolism. Moreover, adenosine and/or arbutin could be used as a substitute for CY in treating SCM, and allantoin efficacy was slightly weaker. This integrated metabolomic approach performed excellently in understanding the herbal function and the roles of its components.

[Regionalization study of Dioscorea nipponica in Jilin province based on MaxEnt and ArcGIS].

At the urgent practical issue of resource protection and artificial cultivation area selection of Dioscorea nipponica, the dominant environmental factors affecting the distribution of D. nipponicain Jilin province were selected by field investigation and using the maximum information entropy model and geographic information technology. MaxEnt model study found that the standard deviation of seasonal variation of temperature, precipitation in October and other six environmental factors on the growth of D. nipponica are the greatest impacting factors. The range of suitability for the growth of D. nipponica was 4.612 08×10-6-0.544 31, and the regionalization study was divided into four parts: high fitness area, middle fitness area, low fitness area and unfavorable area. The high fitness area is concentrated in the central and southern areas of Jilin Province, using ArcGIS statistical environment factors in the appropriate area of the numerical situation. The results showed that the regionalization study of D. nipponica was basically the same as the actual situation. It is clear that the natural environment suitable for the growth of D. nipponica is also the basis for the protection of the resources and the selection of cultivated area.

[New variety breeding of Dioscorea alata, cultivar "Wenshanyao No.1].

To breed a new yam cultivar of Dioscorea alata, the different and excellent germplasm resources were investigated within artificially cultivated population and some superior individuals, with a higher yield and medicinal properties, were selected. Considering results of the yield and medicinal properties during 2006-2013 cropping season, strains and lines were established and selected. As a result, the yield of the new developed cultivar (Wenshanyao No. 1, WSY01-1) reached 2217. 0 kg per 667 m2 (fresh weight) and 348.3 kg per 667 m2 (dry weight), and increased 23.8% and 23.9% comparing with control cultivars (landraces). Comparing with control cultivars, the level of polysaccharide, allantoin, and dioscin increased 36.9%, 48.3%, 20.9%, and reached 12.2%, 1.30%, 579.7 µg · g(-1), respectively. This result showed that the systematic selection method can significantly improve yield and medicinal properties of D. alata, and the developed " Wenshanyao No. 1" exhibits wide spreading prospects.

[Study on Rapid Micropropagation in Vitro Technique of Guangfeng Medicinal Yam (Dioscorea opposita) Plantlets].

OBJECTIVE: In order to provide methodology reference for virus-free and germplasm conservation of Guangfeng medicinal yam (Dioscorea opposita) plantlets, rapid micropropagation in vitro technique of Guangfeng medicinal yam plantlets was studied. METHODS: Using the method of plant tissue culture, single factor test and flow-cytometry, the basic procedure of Guangfeng medicinal yam tissue culture was established and the DNA content of Guangfeng medicinal yam plantlets and its potted seedlings was detected. RESULTS: The best disinfection procedure of stems with a bud of Guangfeng medicinal yam was washed with sterile water for three times after sterilized with 70% alcohol for 20 - 30 s and then washed with sterile water for three times again after sterilized with 0.1% mercuric chloride for 10 - 12 min; The best explants of stems with a bud of Guangfeng medicinal yam was slightly woody and more mature stems witha bud; The best proliferation culture medium of stems with a bud of Guangfeng medicinal yam was MS + 6-BA 2.0 mg/L + NAA 0.1 mg/L; The best rooting culture medium of stems with a bud of Guangfeng medicinal yam was MS + NAA 0.5 mg/L; The best culture method of Guangfeng medicinal yam plantlets was liquid culture; The best transplanting matrix of Guangfeng medicinal yam plantlets was the mixture of paddy clay and fine sand (1: 2) or the mixture of perlite and vermiculite (1: 2); The DNA content between Guangfeng medicinal yam plantlets and its potted seedlings had no significant difference. CONCLUSION: A fast and efficient micropropagation in vitro technological system of stems with a bud of Guangfeng medicinal yam is established, and the flow cytometry detect results also show the genetic stability of Guangfeng medicinal yam plantlets, whose results provide the technical and theoretical basis for the large-scale production of Guangfeng medicinal yam plantlets.

[Studies on genetic relationship of Dioscorea].

Based on the results of the morphologic studies on genus Dioscorea, the paper summarized the entire chemical constituent that isolated from this genus and analyzed it with the methods of chemotaxonomy. The rules of the chemical constituent and pharmacodynamic effects were analyzed. Seventeen species which belong to Sect. Stenophora Uline of Dioscorea contain steroidal sapogenin. Other species with different main components such as polysaccharide and tannin have have different effects. This chemotaxonomic view point will conduce to establish a phylogeny of the genus Dioscorea.

[Research on Breeding of Dioscorea opposita cv. Tiegun].

OBJECTIVE: To breeding the new varieties Dioscorea opposita cv. Tiegun with the best comprehensive properties. METHODS: Seven new Dioscorea opposita. cv. Tiegun cultivars were screened by space mutation breeding of Dioscorea opposita cv. Tiegun bulbils. Yield,allantoin content,water soluble extractive and the resistance of these seven cultivars were compared with the main cultivar Dioscorea opposita cv. Tiegun( CK). Meanwhile, the nutrition quality of new cultivars No. 6 and No. 10 were compared with the main cultivar. RESULTS: (1) The fresh weight per plant ranked in the order as follows: No. 6 > No. 10 > No. 4 > No. 9 > No. 1 > CK > No. 2 > No. 8. The drying rate ranked in the order as follows: No. 2 > No. 10 > No. 9 > No. 6 > No. 8 > CK > No. 1 > No. 4. Dry weight per plant ranked in the order as follows: No. 10 > No. 9 > No. 6 > No. 2 > No. 1 > CK > No. 4 > No. 8. The fresh weight per plant, drying rate and dry weight per plant of No. 6 and No. 10 were higher than the main cultivar. (2) The allantoin content ranked in the order as follows: No. 6 > No. 4 > No. 10 > CK > No. 9 > No. 8 > No. 2 > No. 1. (3) The water soluble extractive contents ranked in the order as follows: No. 6 > No. 2 > No. 4 > No. 10 > No. 1 > CK > No. 9 > No. 8. The water soluble extractive content of No. 6 was higher than No. 10 and the main cultivar. (4) No. 10 had the best taste of dry, soft, sweet and fragrant, No. 6 had the taste of dry, floury and hard, and No. 9 had the taste of dry and crisp. (5) No. 6 had the strongest resistance to Gloeosporium pestis and Cykindrosporium dioscoreae; No. 10 had a middle resistance to Gloeosporium pestis and a strong resistance to Cykindrosporium dioscoreae; and the main cultivar had a middle degree of being prone to Gloeosporium pestis and a middle resistance to Cykindrosporium dioscoreae. (6) The content of starch, reducing sugar, protein and ash in No. 6 and No. 10 were higher than that of the main cultivar,while the content of water in No. 6 and No. 10 were lower,which indicated that the nutrition quality of No. 6 and No. 10 is better than the main cultivar. CONCLUSION: The new cultivar No. 10 is suitable for popularizing as a new variety of edible Dioscorea opposita cv. Tiegun. The new cultivar No. 6 is suitable for popularizing as a new variety of medicinal Dioscorea opposita cv. Tiegun.

[Evolution and change of the species quality and authentic producing areas of Dioscorea opposita Thunb].

Yam was first recorded in Shen nong Ben cao Jing (Shennong's Classic of Materia Medica) which was basically came from Dioscorea opposita since ancient time. Before the Tang dynasty, it basically came from the wild species of Dioscorea opposita. In the Song Dynasty, D. opposita began to be cultivated, but Chinese medical practitioners claimed that the wild species was better than the cultivated one. After the Ming and Qing Dynasties, yam was mostly from cultivated resources. As the species quality changed, the authentic producing area of Dioscorea opposite was recognized to be in Huaiqing, Henan province, since the Ming and Qing Dynasties. Through long-term cultivation, the species produced in Huaiqing began to differentiate and the Chinese medicinal experts of successive ages considered that the product quality of yam is excellent and if it revealed the features of"white, thin, solid quality", that was the best, and this is consistent with the species called"Tiegun (iron stick)" Diascorea opposita cultivated by Huaiqing farmers. Hence, the title of"Huaiqing yam" is not the general title for the authentic species of yam produced in the Huaiqing region (now Jiaozuo city, Jiyuan city, and Xinxiang city of Henan Province), but strictly refers to that species commonly and long recognized by TCM specialists as the Tiegun Dioscorea opposita.

Effect of delayed harvesting and pre-treatment methods on the antinutritional contents of trifoliate yam flour.

Effects of delayed harvesting and pre-treatment methods on the anti-nutritional contents of trifoliate yam flour were examined. Trifoliate yam tubers were washed, peeled, sliced and subjected to pre-treatment methods, such as soaking, pre-cooking and blanching/soaking. The phenols, phytate, oxalate, tannin and alkaloid profiles of the flours were evaluated and the values of phenols, tannin, oxalate and phytate contents were 0.02-0.32, 0.04-0.53, 0.11-4.32 and 0.20-1.05mg/100g, respectively. The predominant alkaloids in trifoliate yam flour were dioscorine and dihydrodioscorine. The white trifoliate yam flour had higher levels of anti-nutrients than the yellow trifoliate yam flour. Alkaloid contents of trifoliate yam flour increased slightly with delayed harvesting periods. Blanching/soaking method drastically reduced the anti-nutrient contents of trifoliate yam flour than other methods.

[Study on inducing embryogenic callus of Dioscorea zingiberensis by orthogonal design].

OBJECTIVE: To select the suitable medium to induce embryogenic callus of Dioscorea zingiberensis. METHODS: Plantlet of Dioscorea zingiberesis in vitro was obtained by using apical meristem as explant. The different parts of the plantlets were cultured to select the best explant used for inducing callus and embryoids. Growing rate and diosgenin content were calculated in orthogonal test to optimize combination of phytohormones for inducing embryogenic callus. RESULTS: The leaves were suitable explants to induce callus and embryoid. The inducing rate of callus and embryoids reached 92.5% and 42.5%, respectively. The optimal medium for inducing embryogenic callus was MS + 6-BA 2.0 mg/L + NAA 0.5 mg/L + 2,4-D 1.0 mg/L. CONCLUSION: The results of this study can be used for effective induction of embryogenic callus of Dioscorea zingiberensis, and lay the foundation for the subsequent research of artificial seeds.

Ethylene treatment improves diosgenin accumulation in in vitro cultures of Dioscorea zingiberensis via up-regulation of CAS and HMGR gene expression

Background: The perennial medicinal herb Dioscorea zingiberensis is a very important plant used for steroid drug manufacturing for its high level of diosgenin in rhizome. Although the stimulation of diosgenin accumulation by ethylene has been reported in a few of plant species, its regulation is not yet characterized at the molecular level, the underlying molecular mechanism remains elusive. Results: In this study, the effects of ethylene on diosgenin biosynthesis in in vitro cultures of D. zingiberensis were described. The results showed that, in samples treated with ethylene at concentration E3 (10(4) dilution of 40% ethephon), the diosgenin biosynthesis was significantly promoted in comparison with the control samples. Treatment with high concentrations of ethylene had inhibitory effect, whereas with low concentration of the gas elicitor brought about no detectable deleterious effect on the growth rate and diosgenin content of the cultures. The considerable increase of diosgenin level in in vitro cultured Dioscorea zingiberensis by ethylene application is accompanied by the concomitant increase of soluble proteins and chlorophyll content. The gene expressions of cycloartenol synthase and 3-hydroxy-3-methylglutaryl-CoA reductase but not of squalene synthase or farnesyl pyrophosphate synthase were up-regulated by applied ethylene. Conclusions: Our results suggest that ethylene treatment enhanced diosgenin accumulation via up-regulation of the gene expressions of cycloartenol synthase and 3-hydroxy-3-methylglutaryl-CoA reductase.

[Numerical analysis of morphological variation of germplasm resources of dioscorea].

OBJECTIVE: Botanical characters of germplasm resources of Dioscorea were observed and compared, which could to offer reference for its genetic improvement, germplasm resource identification and classification. METHOD: Based on field cultivation, twenty-four morphological traits of ninety-four Dioscorea germplasm resources were observed or determined. And the morphological differences among germplasm resources were compared by principal component analysis and cluster analysis. RESULT: There were ample morphological diversity in the twenty-four traits, in especially in leaf size and tuber characters of the ninety-four Dioscorea germplasm resources. The first seven principal components which accounted for 80. 957% of total variance were extracted from the principal component analysis. The ninety-four germplasm resources could be divided into four clusters, which belonging to Dioscorea opposite, D. persimili, D. fordii and D. alata respectively. CONCLUSION: There were large morphological variation among germplasm resources on Dioscorea. Identification of germplasm resources of Dioscorea should focus on leaf size and tuber characters.

[Variation of endogenous hormones in formation of microtuber of Dioscorea opposite in vitro].

OBJECTIVE: Through analysis of variation and function of 5 main endogenous hormones in the formation of microtuber of Dioscorea opposite in vitro to explore the physiological and biochemical mechanism of microtuber development. METHOD: When microtubers were induced on MS + 6-BA 1.5 mg x L(-1) + NAA 1.5 mg x L(-1) + sucrose 5% medium, the endogenous hormones were isolated during different formation stages of microtubers, then purified and detected with enzyme-linked immunosorbent assays (ELISA). RESULT: The results showed that GA3 slightly decreased in initial period, rose suddenly 20 days later, and than decreased. IAA showed a dropping tendency in the total course, ABA and ZR increased in a long period, dropped at last. JA continuously rose and never dropped, GA3 and ABA and the ratio of GA3 and JA varied obviously. CONCLUSION: IAA, ABA, JA , ZR and GA3 play an important role in controlling formation of microtubers in D. opposite in vitro.

[Application of orthogonal design in tissue culture of Dioscorea opposite].

OBJECTIVE: To study the effects of different factors on buds and microtuber. These factors included plant growth substances and sucrose. METHOD: stems were selected as explants. The effects of three kinds of factors were studied by orthogonal design method including sucrose, 6-BA, NAA on the buds and microtuber induction. The data were analyzed with range analysis and vadance analysis. RESULT AND CONDUSION: The optimal media to induce many buds from stems were MS + 6-BA 1 mg x L(-1) + NAA 1 mg x L(-1) + sucrose 3%, the effect of the three factors was in sequence of sucrose >6-BA > NAA. The optimal media to induce microtuber from stems were MS+6-BA 1.5 mg x V1 +NAA 1.5 mg x L(-1) + sucrose 5%, the effect of the three factors was in sequence of sucrose >6-BA > NAA.

[Textual research on origin and development of genuine medicinal herbs of Shanyao].

Making textual research on Bencao and documents, this article inquires to the origin and development of genuine medicinal herbs of Shanyao (Rhizoma Dioscoreae) on the points of change of the growing areas and the development of cultivating and processing techniques and clinical uses. The study indicates that the medicinal use of Dioscorea oposita went through several periods: the period of the use of wild D. oposita before Tang dynasty, the period of the mixed use of wild and cultivating D. oposita from Song to the middle of Qing dynasty, and the period of the main use of cultivating D. oposita after the latter stage of Qing dynasty (18th century). It considers that the growing area of genuine medicinal herbs of Shanyao appeared in Ming dynasty and finally formed "Huaishanyao" on the early of 20th century. The acknowledgement of Huaishanyao as genuine medicinal herbs is related closely to its cultivating and processing techniques and clinical uses. The development of cultivating techniques provided the resource of Shanyao, the invention of processing techniques improved its appearance and quality, and the clinical uses and practices by modern and contemporary famous medical men played an important role to the social approval and development of Huaishanyao.

Arbuscular mycorrhizal fungal communities in sub-Saharan savannas of Benin, West Africa, as affected by agricultural land use intensity and ecological zone.

The rapid decline of soil fertility of cultivated lands in the sub-Saharan savannas of West Africa is considered to be the main cause of the increasingly severe constraints of food production. The soils in this tropical area are highly fragile, and crop yields are limited by characteristically low levels of available phosphorus. Under such preconditions, the multiple benefits of the arbuscular mycorrhizal (AM) symbiosis are likely to play a pivotal role for maintaining natural soil fertility by enhancing plant nutrient use efficiency, plant health, and stabilization of a favorable soil structure. Thus, it is important to explore the impact of the commonly applied farming practices on the native AM fungal community. In the present study, we determined the AM fungal species composition in three ecological zones differing by an increasingly prolonged dry season from South to North, from the Southern Guinea Savanna (SG), to the Northern Guinea Savanna (NG), to the Sudan Savanna (SU). In each zone, four "natural" and four "cultivated" sites were selected. "Natural" sites were three natural forest savannas (at least 25-30 years old) and a long-term fallow (6-7 years old). "Cultivated" sites comprised a field with yam (Dioscorea spp.) established during the first year after forest clearance, a field under mixed cropping with maize (Zea mays) and peanut (Arachis hypogaea), a field under peanut, and a field under cotton (Gossypium hirsutum) which was the most intensively managed crop. Soil samples were collected towards the end of the wet season in each zone. AM fungal spores were extracted and morphologically identified. Soil subsamples were used to inoculate AM fungal trap cultures using Stylosanthes guianensis and Brachiaria humidicola as host plants to monitor AM root colonization and spore formation over 10 and 24 months, respectively. A total of 60 AM fungal species were detected, with only seven species sporulating in the trap cultures. Spore density and species richness were generally higher in the natural savannas and under yam than at the other cultivated sites and lowest under the intensively managed cotton. In the fallows, species richness was intermediate, indicating that the high richness of the natural savannas was not restored. Surprisingly, higher species richness was observed in the SU than in the SG and NG, mainly due to a high proportion of species in the Gigasporaceae, Acaulosporaceae, and Glomeraceae. We conclude that the West African savannas contain a high natural AM fungal species richness, but that this natural richness is significantly affected by the common agricultural land use practices and appears not to be quickly restored by fallow.

[Quality comparison between two cultivated Chinese yam-Kunming yam and Tiegun yam].

OBJECTIVE: To compare the quality of cultivated Chinese yam (Dioscorea polystachya Turcz.) from Yunnan (Kunming yam) and Henan (Tiegum yam) by determining the content of dry substance in fresh sample and the contents of water extracts, ethanol extracts, starch, protein, crude-fat and polysaccharide in dry sample. METHOD: The above-mentioned indexes were determined by methods of air desiccation, cold-immersing, hot-immersing, iodine-blue coloration, half Micro-Kjeldahl, Soxhlet extraction and spectrophotometric method respectively. RESULT: In fresh sample, the content of dry substance of Kunming yam is a little lower than Tiegun yam; in dry sample, all indexes of Kunming yam are higher than or approach to those of Tiegun yam except the content of crude-fat. Especially the content of polysaccharide in Kunming yam is 64% higher than that of Tiegun yam. CONCLUSION: Kunming yam, with high quality, high yield and good taste, deserves paying close attention as a good variety.

Carbohydrate metabolism in Dioscorea esculenta (Lour.) Burk. tubers and Curcuma longa L. rhizomes during two phases of dormancy.

We have examined the changes in carbohydrate metabolism in food yam (Dioscorea esculenta (Lour.) Burk.) tubers and in an economically important spice cum medicinal plant turmeric (Curcuma longa L.) rhizomes under storage. Both specimens showed varied levels of dormancy and sprouting appeared at the end of dormant period. Harvested, fully matured tubers of yam and rhizomes of turmeric were stored in wooden boxes under the conditions of 28+/-2 degrees C temperature and 65-75% relative humidity (RH) in dark. The starch, sugars, enzymes of starch degradation, respiration, glycolysis, tricarboxylic acid (TCA) cycle and oxidative pentose phosphate pathway (PPP) were studied during 1-70 days after harvest (DAH). This investigation revealed that, the starch degradation and the enzymes involved, viz. alpha-amylases and starch phosphorylase showed a lower level of activity during early period of dormancy, while sugar content and enzymes of carbohydrate metabolism increased rapidly during sprouting. The isoenzymic profiles of alpha-amylases showed marked variations in these two phases. The key enzymes of glycolysis, TCA cycle and PPP, viz. aldolase, succinic dehydrogenase, malic dehydrogenase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were increased even before the visible appearance of sprouting and their activities were at their maximum during sprouting. Based of the observations the dormancy period may be distinctly divided into peak period of rest and presprouting period.