Recycling of ligno-cellulosic residues and economically viable crops production with improved water use efficiency is imperative to secure high-quality sustainable food production and implement the environmental sustainability. Therefore, the objective of this work was to evaluate superabsorbent sugarcane bagasse polymer composite (SBP) on Stevia rebaudiana quality and production under deficit irrigation. The experiment was conducted at Sabahia Agricultural Research Station, Alexandria, Egypt during two seasons 2017/2018 and 2018/2019 under the greenhouse conditions. Three SBP treatments (0.0, 2.0 and 4.0 g/5 kg of soils) using three irrigation levels (100%, 70% and 50% of field capacity) were applied. Data revealed that the soil amendment with SBP enhanced and gave the highest values of stevia growth parameters, chlorophyll, total soluble carbohydrate and steviol glycoside (SVglys) under both irrigation systems in both seasons. The SBP at dosage 2 and 4% levels into the soil led to an increase of dry leaves yield by 1.5 and 1.32 fold, respectively compared to yield in untreated soil under 70% field capacity. Calculated SVglys and determined by IR was high in soil amendment with 2.0% SBP (15.60%) under 100% irrigation levels and nearly closed in 70% irrigation level (15.02%). SBP application under deficit irrigation conditions increased of amount WUE and showed improvement in peroxidase isozyme system that can be used as a biomarker for characterizing drought stress tolerance. Hence, it could be recommended that SBP can be used to enhance the stevia productivity and enabled the survival of stevia plant under deficit irrigation conditions.

Tissue culture methods are useful in assessing the tolerance of various stresses due to the ease of controlling stress under in vitro conditions. This study aimed to investigate the response of sugarcane genotyps to drought stress using calli as a model system. For inducing sugarcane callus, the medium of Murashige and Skoog (MS) was used with different mannitol concentrations (100, 200, and 300 mM) to measure their effects on callus frequency, the day of callus initiation, embryogenic potential, relative growth rate (RGR), water and proline contents, K+ and Na+ contents, as well as the formation of shoot and roots for three sugarcane genotypes (e.g., GT 54-9, G 84-47, and pH 8013). The RAPD-PCR analysis was carried out using five oligonucleotide primers to identify the genetic variation among sugarcane genotypes. The results indicated that the degree of callus proliferation varied from 70 86%. The highest value of callus proliferation, PGR, shoot formation was recorded for the genotype GT 54-9 compared to the other two genotypes (G 84-47 and pH 8013). Calli treated with 100 mM mannitol showed the highest RGR, pro line and waer contents for the genotype GT 54-9, while, those treated with 300 mM recorded the lowest values of these parameters for the genotype pH 8013. The genotype G 84-47 collected highest Na+ content, while the genotype pH 8013 collected highest K+ content. The results of this study recommend preference for GT 54-9 genotype, which is considered the most promising genotype, showing more tolerance to drought stress based on all studied traits. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.

This study was conducted at El-Mattana Agricultural Research Station, Luxor Governorate, Egypt (latitude of 25.17° N and longitude of 32.33°E) on three sugar crop cycles 2017/18 (plant cane crop), 2018/19 (the first ratoon) and 2019/20 (the second ratoon) to screen sugarcane genotypes for yield, quality and borer resistance, also estimates the relationship among agronomical and pathological traits based on principal components biplot analysis.Results revealed that significant differences among sugarcane genotypes in susceptibility to the lesser sugarcane borer, Chilo agamemnon infestation measured as bored stalk%, bored joints %, girdled stalks%, mean no.holes/joint, mean no.holes/bored joint and mean no.holes/stalk in the three studied seasons.In plant cane and first ratoon seasons the genotype L 62-96 exhibited the highest bored stalk %.While, in the second ratoon, the genotype G.T.54-9 was recorded the highest bored stalk %.Three genotypes (F.150, M 57-35 and G. 2008-20) were the most tolerant in plant cane season recording the lowest bored stalk%.While, in the 1 st ratoon season, 88/5-27 and SP72-5181 genotypes were recording lowest bored stalk%.Meanwhile, in the 2 nd ratoon season, SP 81-3250, F. 150, F 161 and G. 2007-61 genotypes were recording lowest bored stalk% respectively.

The aim of the present investigation was to improve steviol glycosides (SGs) of three stevia varieties; Sponti (SPNT), China1 (CHN) and EGY1 (EGY) by obtaining new genotypes with high ratio of rebaudioside A (rebA)/stevioside (stv) using five different doses of colchicine(0, 0.025, 0.05, 0.1 and 0.2%), during 2018 and 2019 seasons at ElSabahya Research Station, Alexandria Governorate. Plants with a significant large leaf area/plant and significantly high number of leaves/plant, as well as dry matter content from the three commercial varieties, were selected and evaluated for their steviol glycosides content by using high performance liquid chromatography (HPLC). Results of buds survival rate, showed that SPNT and EGY varieties performed better than CHN. SPNT-22, CHN-31, EGY-22, EGY-23and EGY-31 mutated clones showed a significant superiority for most desirable morphological characters (leaf area/plant, number of leaves/plant as well as dry matter content)compared to other tested genotypes. HPLC showed that the sweetener contents stv and reb A percentages were affected by polyploidy induced by colchicine. Best ratio of reb A/stv was recorded by CHN-31 (3.846) which was 4.2 times higher than CHN (0.919). CHN-31, EGY-22 and EGY-31 clones recorded the highest reb A + stv percentage (77.25, 78.33 and 76.18, respectively). For EGY-31(a new clone), rebA/stv percentage was 2.6 higher compared to its commercial variety, this, consequently, decreases the bitter taste and aftertaste and increases sweet flavor. New genotypes (CHN-31and EGY-31) were obtained and selected as the best clones due to the higher sweeteners percentages recorded, which might help in meeting diabetics needs in the future

Nowadays, Stevia rebaudiana leaves have attracted economic interest as a natural non-nutritive, non-toxic, high-intensity sweeteners as well as its therapeutic benefits. The aim of the study was established an efficient regeneration protocol to improve stevia's sweetness with enhancing productivity of stevia leaves as well as to evaluate the possible suitability of this technique to be applied to rapid production. The young leaves and hypocotyl of Stevia rebaudiana namely Spanti explants were cultured on a MS medium supplemented with different concentrations and combination of NAA, 2,4-D and BAP as plant growth regulators. The results showed that leaf explants obtained highest callus formation (100%) on MS medium supplemented with 0.5 mg/l NAA while callus formation from hypocotyl explants was (92.5%) on MS medium contains 1.0 mg/l 2,4-D and 2.0 mg/l NAA. Callus derived hypocotyl failed to differentiate, while callus resulting from young leaf explants were differentiated into shoots on MS medium supplemented with 2.5 mg/l BAP. MS containing 1 mg/l BAP and1 mg/l 2,4D showed best results in steviol glycoside components and high rebaudioside A (RA) (24.22 mg/g callus) yield comparing with other used media under inoculation for 18 hrs light. Also this media gave the high rate of RA over stevioside (1.33) as an indicator of leaves quality with the sweetness intensity rate under the same experimental conditions. Medium with 1.0 mg/l IBA was suitable for rooting stevia shoots. Plantlets were acclimatized by 64% in the soil contain beat moss, sand and perlite (1:1:1) under controlled chamber at 28°C for one month which transferred to the green house.Key words: Non-nutritive, callus formation, hypocotyl explants, steviol glycoside.

A field trial was carried out to evaluate 544 sugarcane clones (genotypes) and 3 check cultivars under un-replicated augmented design with eight unbalanced blocks at Giza Agricultural Research Station, Egypt (latitude of 30° 0' N, and longitude of 31° 12' E) in 2016/2017 seasons. The present work deals with the estimation of variance components, heritability, prediction accuracy and efficiency of selection in a population of 19 sugarcane families at single stool stage of breeding program using REML/BLUP (Restricted Maximum Likelihood/Best Linear Unbiased Prediction). Based on one-way and augmented block design without replication, the results showed low genetic variability among the evaluated families in stalk length, diameter, weight and number per stool. The narrow-sense heritability estimates ranged between the lowest (5.98%) for stalk number/stool to the highest (52.06%) for Brix%. Analysis of variance revealed significant differences among the evaluated clones for all the traits. The mean estimated through components via BLUP facilitated the selection of six families; number (1, 10, 3, 9, 17 and 2) as superior ones, respectively. The use of the augmented block design without replication in family selection experiments proved inadequate due to the low estimates of selective accuracy and family mean heritability. Owing to the large number of families and the use of the REML/BLUP procedure, either using or not using the checks in the analysis did not alter the estimated genetic parameters. Based on the individual BLUP in sugarcane selection, high differences within family for the yield main components were detected. The highest genotypic effects and high-predicted values for stalk weight per stool were recorded by the sugarcane clones number (375, 495, 31 and 359), while the highest for Brix% were recorded by clone’s number (429, 259, 432 and 258). The results suggested that individual clone selection by BLUP procedure could indicate a higher number of promising clones for quantitative traits within families with high genotypic effects.