Stevia leaves contain various components, such as flavonoids, labdanes, chlorophylls, sterols, triterpenoids, mono-disaccharides, organic acids and inorganic salts. Stevia is known to accumulate diterpenoid steviol glycosides, which are approximately 300 times sweeter than regular sugar. Stevioside and rebaudioside A are the main diterpenic glycosides in stevia. Steviol glycosides are the secondary metabolites responsible for the sweetness of stevia. The main objectives of the present study were to determine the concentrations of diterpenic glycosides (stevioside and rebaudioside A) in three stevia varieties (
Stevia rebaudiana) via
the HPLC-UV technique and to amplify the UGT76G1 gene by PCR using gene-specific primers. The expression levels of the UGT76G1 gene were determined in the three stevia varieties. The PCR products were sequenced and analyzed, and the nucleotide sequences of the UGT76G1 gene were submitted to GenBank and assigned to the following three varieties: Egy1 (MH087463), China1 (MH087464) and Sponti (MH087465). Cluster analysis was used to separate the three varieties into two major clusters based on their phylogenetic relationship. In addition, chemical analysis was carried out to evaluate stevioside and rebaudioside A. The present study concluded that Egy1 and Sponti are closely related varieties as they fall in the same cluster, while China1 forms a separate cluster. Bioprospecting studies could be useful for selection of superior ecotypes of
Stevia rebaudiana
.
Two field experiments were carried out in km 71 West Alexandria-Cairo desert Road during 2014/15 and 2015/16 seasons to study the response of some multigerm sugar beet varieties i.e., Top, Sultan and Kawemira to foliar spray with compost tea at three levels of (0, 15 and 20 L/fed/300 L water) at 45 and 75 days from sowing. The experimental design was a split plot design with three replicates, foliar spray with compost tea levels were arranged in the main plots and sugar beet varieties were allocated in the sub plots. The results showed that foliar spray with the level of 20 L/fed with compost tea significantly increased root length, diameter, fresh weight/plant, sucrose%, purity%, root and sugar yields/fed in both seasons, while, decreased root mineral contents (α amino N, Na and K %) as compared with zero treatment (control) or 15 L/fed level of compost tea. The Three tested varieties were differed significantly in the root length, diameter, fresh weight/plant, sucrose%, purity%, root and sugar yields/fed and root mineral contents. Kawemira variety surpassed the other two varieties (Sultan and Top) in the most traits in both seasons. Foliar spray with compost tea increased the numbers of two sugar beet insects, beet fly (Pegomya mixta Vill.) and tortoise beetle (Cassida vittata Vill.). Kawemira variety was less attracted by the two previous insects, during two successive seasons. Moreover foliar spray with compost tea at level 20 L/fed recorded the highest values for sucrose %, root and sugar yields/fed in both seasons. Generally, it could be recommended that sown Kawemira, Sultan and Top varieties, respectively and sprayed with 20 L/fed compost tea produced the highest sucrose%, root and sugar yields/fed and yield quality in a sandy soil.
Two field experiments were carried out in 2013/2014 and 2014/2015 seasons at Nubaria Research Station, El-Beheira Governorate, Egypt to study the response of three sugar beet cultivars to the foliar nutrition with pigeon manure tea (PMT) in combination with soil N fertilizer and its effect on yield, yield components, chemical constituents and some physiological and genetical parameters. A split plot arrangement in a Randomized Complete Block Design with three replications was used. Three polygerm sugar beet cultivars namely SN-626, NH-627 and Hercule were randomly distributed in the main plots, while the four combinations of PMT and N fertilizer were randomly distributed in the sub-plots, it was as follows; 80 kg N/fed (recommended level) was given as soil application, without PMT (check treatment) (C1), foliar application of 2.5% PMT + soil addition of 40 kg N/fed (C2), foliar application of 5% PMT + soil addition of 40 kg N/fed (C3) and foliar application of 10% PMT + soil addition of 40 kg N/fed (C4). The results illustrated that fertilizing the tested cultivars with (C4) treatment attained the highest mean of sugar yield compared with (C2) and/or (C3), in the two seasons. The three cultivars showed that the highest and the least values of root, top, sugar yields and sucrose% were produced from SN-626 and Hercule cultivar, respectively, in both seasons. Genotypic and phenotypic variances, heritability and coefficient of variance as percent of means were estimated for the studied traits. Maximum heritability values were obtained for root diameter followed by top yield. Meanwhile, it was moderate for sugar yield, sucrose% and root yield, while the minimum values of heritability were recorded by total soluble solids and purity percentages. Besides, different genetic coefficient of variance as percent of mean, as well as high genetic variability and high range of variations were detected. Path-coefficient analysis revealed that the improvement of different genotypes sugar yield can alter the relative importance of root yield, sucrose% and purity%. Under conditions of the present work, it can be recommended that growing SN-626 variety fertilized with (C4) treatment produced the highest sugar yield/fed with no significant difference from treating the same variety with C1 (recommended level). Also, the data suggest that significant improvement could be achieved by increasing purity as well as sucrose percentages to increase sugar yield.
Four experiments were conducted at El-Sabahia (31°, 12N latitude), Alexandria, Egypt Sugar Cane Research Station to estimate the variability, heritability and flowering ability of eighty eight sugar cane germplasm. All experiments were planted in mid-March 2013 and their design was randomized complete block with three replicates. Variability in important traits among tested germplasm was estimated using genotypic and phenotypic variance in addition to genotypic and phenotypic coefficients and broad sense heritability. Flowering ability was determined using the number and percentage variation of flowering germplasm and flowering dates. The results showed that the magnitude of genotypic and environmental variance was the highest in number of millable cane character and the minimum value was found in stalk diameter in plant crop and both ratoon crops. Maximum genotypic and phenotypic coefficients of variation were exhibited by cane yield and number of millable cane in plant and both ratoon crops, also in single stalk weight and sugar yield in both ration crops. Among quality characters lowest values for both coefficients were obtained by purity percent in plant and both ratoon crops. In the present experiment, moderate to high heritability estimates were observed for all characters. The results indicated that the selection is more effective in plant and both ratoon crops based on yield contributing characters having high PCV, GCV and heritability along with suitable mean value. The flowering occurred in most of studied germplasm under natural environment in El-Sabahia area but the percentage of flowered germplasm differed among studied seasons. The flowering in sugarcane germplasm commenced from November and ended up to June. Most of the germplasm flowered during December at the three seasons and followed by February at plant crop, January and February at first ratoon crop and January and March at second ratoon crop. The tested germplasm were divided into 8 groups according to their flower ability.
Sugar beet breeding program started in Egypt during the last two decades of past century by several Egyptian investigators and breeders, the data was very encouragement. There were three promising multigerm Egyptian sugar beet genotypes (Eg. 6 , Eg. 26 and Eg. 27) have showed good root weight and good sugar percentage at several studied locations. The goal of any sugar beet breeding program is to develop varieties with higher root yield and higher sugar content, better extraction yield (juice purity), higher seed germination percentages, lower tendency to "bolt" and higher resistance to diseases and pests.The objective of this study was to investigate seed properties of the three promising Egyptian sugar beet genotypes (Eg. 6, Eg. 26 and Eg. 27). Seed samples were divided into five fractions according to their size (<3. 35, 3.35, 4.0, 5.6 and 6.3 mm). The data cleared that "Size 3 = 4.0 mm" the most abundant size in all studied samples with average (70.0, 71.1 and 58.5%) in (Eg. 6, Eg. 26 and Eg. 27), respectively. Hundred seed Weight (2.86, 2.90 and 2.54 g), while unit seed Weight values were (0.028, 0.029 and 0.027 g) for (Eg. 6, Eg. 26 and Eg. 27), respectively. Germination percentage, faster germination and seedling vigor were the best in large seed size compared with small seed size.
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