Microbial contamination is a common problem that causes significant losses in plant micropropagation systems. The present study reports on the identification and control of bacterial contaminants in banana in vitro cultures. Twelve isolates belonging to Bacillus pumilus (S2), Bacillus subtilis (R2 and M4), Geobacillus stearothermophilus (S1, S3, S4, P2, M3 and R3) and Paenibacillus spp. (P1, R1 and M2) were identified by sequencing of 16S rRNA, gyrA or gyrB genes. Antibiotic susceptibility testing was performed with the disk diffusion method on bacterial isolates using 36 antimicrobial agents. Some antibiotics, notably Ticarcillin, Penicillin, Ampicillin, Cefazolin and Imipenem, had a broader range of bactericidal activity than others did. When contaminated axillary shoot cultures of banana were treated with 100 or 200 mg·L⁻¹ of ticarcillin, ampicillin or penicillin the bacteria were eliminated, but a reduction in shoot multiplication and growth was observed. These findings contribute to minimizing the losses in the commercial micropropagation of banana.

Developing a successful protocol for banana in vitro culture is a guarantee for the mass propagation of pathogen-free, high-quality, true-to-type planting materials with low production costs. The current work aimed to investigate the influence of increasing copper levels in an MS medium on endophytic bacterial contamination; shoot multiplication; rooting and the acclimatization of in vitro cultured banana; minerals and chlorophyll content; antioxidant enzymes activity; electrolyte leakage; and the genetic stability of banana regenerants. Four different concentrations of copper sulphate (0.025 as a control, and 30, 60, and 120 mg L⁻¹) were examined. The growth of the endophytic bacteria was inhibited at 60 mg L⁻¹ of copper sulphate which recorded zero contamination, without a significant difference at 120 mg L⁻¹. However, 0.025 mg L⁻¹ of copper sulphate was optimal for the maximum shoot number and shoot length (10 shoots and 6 cm, respectively) without significant differences at 30 mg L⁻¹. The root length of banana plantlets was significantly enhanced at 30 mg L⁻¹ of copper sulphate but without significant differences to the control, regarding the number of roots (9.92 cm and 3.80 roots, respectively). In vitro plants were acclimatized successfully at 30 mg L⁻¹ of copper sulphate with 100% survival. The uptake of minerals, antioxidant enzyme activity and electrolyte leakage was improved because of the copper sulphate, but the chlorophyll level decreased. RAPD profiling showed polymorphism in only one plant treated with 60 mg L⁻¹ of copper sulphate, with an average of 1.8%. The genome template stability percentage was almost 100% for all treated plants.

The present study aimed to develop a micropropagation protocol for Cadaman (P. persica x P. davidiana) and Garnem (P. persica x P. dulcis) peach rootstocks. Stem nodal segments with one axillary bud used as explants. MS medium supplemented with different concentrations of BA with or without IBA was studied to determine the best for multiplication stage, The results revealed that MS medium supplemented with 2.0 mg/l BA+0.1 mg/l IBA was optimal for shoot proliferation of Cadaman rootstock, whereas MS containing 2.0 mg/l BA+ 0.0 IBA was advisable to Garnem peach rootstock. Concerning the effect of auxin type and concentration on the rooting stage, IBA at 1.0 mg/l was more effective on rooting induction of Cadaman shoots, whereas in case of Garnem rootstock both IBA and NAA auxins had a similar effect on the rooting process at the concentration of 1.0 mg/l individually. After acclimatization, survival rate was 83% and 63.3% for Cadaman and Garmen rootstocks, respectively.

This work was carried out in four mango rootstocks namely Socaria, Gomera3, Sabre and Hybrid 13/1 during 2014and 2015 seasons to compare its vegetative growth behavior weather it grafted or ungrafted by Naomi mango Var. as a scion. All the obtained results referred that Socaria rootstock gave the highest values off all studied parameters so it is consider a vigorous rootstock , whereas the Hybrid 13/1 rootstock gave the lowest values and this will its dwarfing effect on Naomi scion so this will be useful in high density orchard systems .Other studied rootstocks were intermediate between Socaria and Hybrid13/1 rootstocks.

Excessive consumption of chemical fertilizers in citrus orchards and other fruit crops has caused many negative effects on the surrounding ecosystem, soil composition, fruit quality, and sustainability. in this investigation, two sources of N, k biofertilezers were added as partial alternative of mineral nitrogen at level 100, 75,50 % of its recommended dose and the effet of this on Valencia orange trees vegetative growth, productivity and fruit quality were studeid . the resulls indicated that using bio N with or without Bio k fertilizer with 75% or 50 % of recommended N fertilizer succeded in enhancing most of vegetative , yield and fruit parameters . Moreover, the applying of biofertilizers enhanced the mineral contents in leaves .The purpose of this study is to increase Valencia orange trees' capacity for growth in sandy soil without using an excessive amount of N mineral fertilizer.