Regulation of tomato (Lycopersicon esculentum Mill.) fruit setting and earliness by gibberellic acid and 2,4-dichlorophenoxy acetic acid application

The experiment was conducted with the objective of determining the effects of different concentrations and combinations of the plant growth regulators (PGRs) 2,4-dichlorophenoxyacetic acid (2,4-D) and gibberellic acid (GA3) spray on fruit setting and earliness of tomato varieties. The experiment consisted of one processing (Roma VF) and one fresh market (Fetan), tomato varieties, three levels of 2,4-D (0, 5 and 10 ppm) and four levels of GA3 (0, 10, 15 and 20 ppm) arranged in a 2 × 3 × 4 factorial combinations, in randomized completed block design with three replications. The study indicated that application of 2, 4-D at 5 and 10 ppm hastened flowering and fruiting but reduced number of fruits per cluster, fruit set percentage and final marketable fruit number per plant. However, application of GA3 extended flowering and maturity time and increased fruit number per cluster, fruit set percentage and marketable fruit number per plant over the control. In general, the study indicated that 2, 4-D is important in tomato production to induce fruit setting and earliness and GA3 seems to extend fruit maturity and harvest period while the combined applications have intermediate effects. Therefore, it is important to further investigate the method of application and concentrations of these PGRs at different growing conditions and on different tomato cultivars to assess their role in tomato fruit setting and maturity time.Keywords: Gibberellic acid, 2, 4-dichlorophenoxy acetic acid, tomato, Lycopersicon esculentum mill, fruit setting, fruit earlines

INFLUENCE OF TREATMENT OF SEED POTATO TUBERS WITH PLANT CRUDE ESSENTIAL OIL EXTRACTS ON PERFORMANCE OF THE CROP

Farmers in most developing countries store seed potato ( Solanum tuberosum L.) tubers in traditional storage that invariably leads to rapid deterioration in the quality of the seed tubers due to sprouting and aging. Thus, potato seed tubers senesce and are past their prime when planted. A pot experiment was conducted at Sirinka Agricultural Research Centre, in north-eastern Ethiopia, to evaluate the effect of treating seed potato tubers with crude plant essential oil extracts, on the growth and yield of the potato crop. Treatments consisted of seed potato tubers treated with dill weed, spearmint, black cumin and eucalyptus crude essential oil extracts, each applied at 45, 90 and 135 mg kg-1 of potato tubers for one month, plus a control treatment. The control consisted of untreated tubers. Results revealed that potato plants grown from seed tubers treated with oil extracts from dill weed, spearmint, and eucalyptus at 135 mg kg-1, took the longest time to sprout, flower, and tubers to mature. Potato plants grown from seed tubers treated with dill weed, spearmint, black cumin and eucalyptus crude essential oil extracts at 135 mg kg-1 were 23 - 38% taller than plants from the untreated seed tubers. Similarly, potatoes from these treatments had 21 - 89% more numbers of leaves compared to plants from the untreated seed tubers. Crude essential oils from dill weed at the concentrations of 90 and 135 mg kg-1 and eucalyptus at 135 mg kg-1, had the greatest positive effects on growth and yield of the potato crop.Dans plusieurs pays en d\ue9veloppement, les paysans conservent les tubercules de pomme de terre ( Solanum tuberosum L.) en stockage traditionnel, ce qui est responsable de la d\ue9t\ue9rioration rapide de la qualit\ue9 des semences due au vieillissement et au bourgeonnement des tubercules. Alors, les tubercules de pomme de terre vieillissent et perdent leur fra\ueecheur avant d\u2019\ueatre plant\ue9. Une exp\ue9rimentation en pots a \ue9t\ue9 conduite au Centre de Recherche Agricole de Sirinka au North-Est de l\u2019Ethiopie pour \ue9valuer l\u2019effet du traitement des tubercules de pomme de terre avec des huiles essentiels sur la croissance et le rendement la culture subs\ue9quente. Les traitements consistaient en l\u2019utilisation des huiles essentielles de la fenouille, la menthe verte, du cumin noir et de l\u2019eucalyptus \ue0 diff\ue9rente concentrations (45, 90 et 135 mg kg-1) pour traiter les tubercules de pomme de terre pendant un mois, et un traitement t\ue9moin (tubercules non trait\ue9s). Les r\ue9sultats ont montr\ue9 que les plants de pomme de terre trait\ue9s \ue0 l\u2019huile essentielle de fenouille, menthe verte, et eucalyptus \ue0 135 mg kg-1 ont le plus retard\ue9 le bourgeonnement, la floraison, et la maturation des tubercules. Les plants de pomme de terre cultiv\ue9s apr\ue8s traitement \ue0 l\u2019huile essentielle de fenouille, menthe verte, cumin noir et eucalyptus \ue0 135 mg kg-1 \ue9taient 23 \ue0 38% plus grands que les plants provenant de tubercules non trait\ue9es. De la m\ueame fa\ue7on, les plants trait\ue9s avaient 21 \ue0 89% plus de feuilles que les plants non trait\ue9s. Les huiles essentielles de fenouille \ue0 90 et 135 mg kg-1 et de l\u2019eucalyptus \ue0 135 mg kg-1 ont entrain\ue9 une croissance plus accrue et un rendement plus \ue9lev\ue9 de la culture subs\ue9quente de pomme de terre

PHENOTYPIC DIVERSITY ANALYSIS OF ETHIOPIAN HOT PEPPER (Capsicum annum L.) ACCESSIONS FOR POD AND QUALITATIVE TRAITS

Diverse environmental conditions and variation in farming systems are expected as a base for wide variability in hot pepper germplasm in Ethiopia. Forty-eight accessions were collected  from different agro-ecological zones of Ethiopia where hot pepper is extensively produced and high phenotypic diversity is expected to exist (Meskan, Mareko, Halaba,, Hawassa and Abishege, Asossa , Bale, West Hararghe) and one standard cultivar (Mareko Fana) were used for this study. Therefore, this research was conducted to estimate phenotypic diversity of 49 genotypes for qualitative and fruit quality related traits. Data for qualitative and fruit quality related traits were subjected to analyses of variance separately. The frequency distribution of the genotypes displayed high polymorphism for all traits except for anthocyanins on the stem, leaf colour and dry fruit colour. Moreover, the diversity for qualitative traits was ranging from 0.65 to 0.98 with an overall average Shanon diversity index of 0.88. The highest diversity index was obtained from calyx attachment (98%), anthocyanins on the fruit, canopy and fruit shape, followed by growth habit and fruit shape at blossom end (93%). The Shanon diversity index of H’ of within (88%) and between (12%) regions of collections were obtained, where anthocyanins on the fruit, green fruit color, fruit shape at blossom end and canopy shape and growth habit contributed very high for differentiation between regions of collections. The Principal Component Analysis (PCA) of fruit quality traits showed 55% of the total variance encountered by the first two components in which, fruit volume and surface area, TSS%, pedicel length were associated with the first components, while only fruit shape index were associated with the second component. The cluster analysis using fruit quality traits, the genotypes were distinctly grouped into six clusters with similarity value ranging from 0.15 to 1.27 and inter cluster D² values of 13 to159, with the maximum distance recorded between IV and V (159) and III and V (158) clusters. Therefore, this study demonstrated the existence of high phenotypic diversity among genotypes for qualitative and fruit quality related traits in Ethiopian collections that could be properly conserved and exploited for future variety improvement program

Cucumber RDR1s and cucumber mosaic virus suppressor protein 2b association directs host defence in cucumber plants

RNA-dependent RNA polymerases (RDRs) regulate important aspects of plant development and resistance to pathogens. The role of RDRs in virus resistance has been demonstrated using siRNA signal amplification and through the methylation of viral genomes. Cucumber (Cucumis sativus) has four RDR1 genes that are differentially induced during virus infection: CsRDR1a, CsRDR1b, and duplicated CsRDR1c1/c2. The mode of action of CsRDR1s during viral infection is unknown. Transient expression of the cucumber mosaic virus (CMV)-2b protein (the viral suppressor of RNA silencing) in cucumber protoplasts induced the expression of CsRDR1c, but not of CsRDR1a/1b. Results from the yeast two-hybrid system showed that CsRDR1 proteins interacted with CMV-2b and this was confirmed by bimolecular fluorescence complementation assays. In protoplasts, CsRDR1s localized in the cytoplasm as punctate spots. Colocalization experiments revealed that CsRDR1s and CMV-2b were uniformly dispersed throughout the cytoplasm, suggesting that CsRDR1s are redistributed as a result of interactions. Transient overexpression of individual CsRDR1a/1b genes in protoplasts reduced CMV accumulation, indicating their antiviral role. However, overexpression of CsRDR1c in protoplasts resulted in relatively higher accumulation of CMV and CMVΔ2b. In single cells, CsRDR1c enhances viral replication, leading to CMV accumulation and blocking secondary siRNA amplification of CsRDR1c by CMV-2b protein. This suggests that CMV-2b acts as both a transcription factor that induces CsRDR1c (controlling virus accumulation) and a suppressor of CsRDR1c activity