Acta agriculturae Slovenica, 119/3, 1–13, Ljubljana 2023 doi:10.14720/aas.2023.119.3.13423 Original research article / izvirni znanstveni članek Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation Ekemini OBOK 1, 2 , Francis NW AGWU 1 , Samuel AKPAN 1 Received April 16, 2023; accepted August 31, 2023. Delo je prispelo 16. aprila 2023, sprejeto 31. avgusta 2023 1 Crop Improvement Unit, Crop Science Department, Faculty of Agriculture, University of Calabar, Calabar, Nigeria 2 Corresponding author, e-mail: e.e.obok@unical.edu.ng Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation Abstract: The study examines agromorphological traits and nutrient compositions in three genotypes of eggplants (Solanum melongena ‘ African Beauty F 1 ’ and ‘Melina F 1 ’ and S. aethiopicum ‘Kotobi’) grown from seeds irradiated by gamma rays (γ-ray) with 100 Gy. Experiments were carried out in the screenhouse and experimental field of Crop Science Depart- ment, University of Calabar, Nigeria. Completely randomised design with four replications and randomised complete block design with three replications was used in the screenhouse and field experiments respectively. Eggplant × γ-ray effect re- duced (p ≤ 0.05) seedling emergence, plant height and number of leaves in the nursery at 2 and 4 weeks after sowing. In the field, these traits were consistently lower for irradiated Melina F 1 and Kotobi (p > 0.05) at ten weeks after transplanting. Irradi- ated African Beauty F 1 had the highest (p ≤ 0.05) upper can- opy leaf area (429.54 cm 2 ), higher (p > 0.05) plant height and stem width; lower (p > 0.05) number of branches and leaves. Un-irradiated and irradiated Kotobi had the highest (p ≤ 0.05) fruit load, lower (p ≤ 0.05) fruit volume, weight and yields over four harvest intervals. Carbohydrate and energy contents of Kotobi fruits grown from 100 Gy gamma-ray irradiated seeds were concurrently improved (p ≤ 0.05). Gamma ray irradia- tion had both positive and negative influences on the agromor- phological traits, mineral composition and nutrient profile of eggplants. However, 100 Gy dose of irradiation had a negative effect on fruit characteristics in general. From the results of this study, inconsistent variations in the agromorphological traits of the irradiated eggplants of the three varieties were reported. Therefore, the goal of mutation breeding in eggplant should not undermine the importance of the eggplant genotype as well as the actual radiation dose. Key words: ℽ-ray, eggplant, fruits, induced mutation, ir- radiation, Solanaceae Obsevanje semen jajčevca z ℽ-žarki vpliva na rast rastlin, pri- delek in prehransko vrednost plodov v M 1 generaciji Izvleček: Raziskava preučuje agromorfološke lastnosti in prehransko sestavo treh sort jajčevca (Solanum melongena ‘African Beauty F 1 ’ and ‘Melina F 1 ’ in S. aethiopicum ‘Kotobi’) vzgojenih iz semen obsevanih z gama žarki, jakosti 100 Gy. Po- skusi so bili izvedeni v rastlinjaku in na poskusnem polju usta- nove Crop Science Department, University of Calabar, Nigeria. V obeh primerih je bil poskus zasnovan kot popolni naključni bločni poskus s štirimi ponovitvami. Obsevanje semen jajčevca z gama žarki je zmanjšalo vznik sejank (p ≤ 0,05), višino rastlin in število listov v rastlinjaku dva in štiri tedne po setvi. V polj- skem poskusu so bile vrednosti teh parametrov vedno manj- še pri obsevanih sortah Melina F 1 in Kotobi (p > 0,05) deset tednov po presaditvi. Rastline obsevane sorte African Beauty F 1 so imele največjo listno površino (p ≤ 0,05; 429,54 cm 2 ), ve- čjo višino (p > 0,05) in večjo debelino stebla, a manjšo število stranskih poganjkov in listov (p > 0,05). Neobsevane in obse- vane rastline sorte Kotobi so imele največ plodov (p ≤ 0,05), manjši volume plodov (p ≤ 0,05), manjšo maso in pridelek v vseh štirjih obdobjih pobiranja plodov. Vsebnosti ogljikovih hi- dratov in energetska vrednost plodov sorte Kotobi, zrasle iz se- men obsevanih z 100 Gy gama žarki sta se izboljšali (p ≤ 0,05). Obsevanje semen jajčevca z gama žarki je imelo pozitivne in negativne učinke na agromorfološke lastnosti, mineralno sesta- vo in na prehranski profil plodov jajčevca. Doza obsevanja 100 Gy je imela nasplošno negativni učinek na lastnosti plodov. Iz rezultatov raziskave je razvidno, da so spremembe agromorfo- loških lastnosti jajčevca vseh treh obravnavanih sort, vzgojenih iz obsevanih semen nekonsistetne. Iz tega sledi, da cilji žlahtne- nja z mutacijami ne smejo prezreti pomena genotipa jajčevca kot tudi ne dejanskih doz obsevanja. Ključne besede: ℽ-žarki, jajčevec, plodovi, inducirane mutacije, obsevanje, Solanaceae Acta agriculturae Slovenica, 119/3 – 2023 2 E. OBOK et al. 1 INTRODUCTION Eggplant is a vegetable crop mostly cultivated in tropical and subtropical regions of the world. It belongs to the Solanaceae family and the genus Solanum with more than 90 genera comprising nearly 3,000 species (Melissa, 2017; Singh et al., 2006). Eggplant has been rec- ognized as the fifth most economically important Solan- aceous crop after potato (Solanum tuberosum L.), tomato (Solanum lycopersicum L.), pepper (Capsicum annuum L.) and tobacco (Nicotiana tabacum L.) (FAO, 2014). Eggplant has a very low caloric value and is considered among the healthiest vegetables with high vitamin, min- eral and bioactive compounds (Raigon et al., 2008; Plazas et al., 2013; Docimo et al., 2016). It is very common in rich dishes such as stews and soups (Edem et al., 2009; Chinedu et al., 2008). The need for improved eggplant varieties for sustainable production and adaptation to cli- mate change challenges cannot be overemphasized. The low yielding ability of the crop has been attributed to lack of varietal replacement through development of hybrid and persistent use of traditional practices coupled with the influence of environmental degradation (Chinedu et al., 2008). Increasing crop yields is a major demand for assuring food security and as such mutagenesis is an important tool to improve crops (Beyaz et al., 2017). As an alternative to natural mutation, which can take years, inducing mutations with different mutagens has greatly aided breeding projects in a variety of ways. Many stud- ies have reported that genetic variability for numerous desired traits may be successfully created through mu- tations, and its application in plant development pro- grammes is well known (Chopra, 2005). Because of its penetrating capabilities, gamma irradiation is one of the most successful techniques of creating genetic diversity in plants when compared to other ionising radiations (Moussa, 2006), as well as in the production of new vari- eties (Animasaun, 2014; Mohamad et al., 2006). Gamma- ray photons have the shortest wavelength in the electro- magnetic spectrum, and therefore possess more energy which gives them the ability to penetrate deeper into the plant tissues (Amano, 2006). Accordingly, gamma irra- diation has been used to induce mutation and still shows great potential for improving vegetative plants (Predieri, 2001). Mutation breeding is utilised in addition to tradi- tional plant breeding because it has a stronger potential for enhancing plant architecture and resulting in im- proved crop development (Khin, 2006). Gamma rays are used in inducing mutations in seeds, and other planting materials such as cuttings, pollens or callus cultures (Ali et al., 2015). Gamma rays are also being widely used as mutation techniques in an attempt to improve morpho- logical and plant growth characteristics. For example, gamma ray irradiation was used to extend the shelf life of tomatoes (Antaryami et al., 2016) and to improve potato storage capacity (Nouani et al., 1987) as well as the mor- phological traits in pepper (Abu et al., 2020). This can also be of great value and benefit for the improvement of eggplant. The improvement of eggplants through crea- tion of variability using gamma rays would enable the selection of high yielding genotypes with improved agro- morphological characters and increase the crop’s agricul- tural productivity. Thus, the objective of this study was to assess the effect of gamma irradiation on the growth and yield traits of three varieties of eggplants. 2 MATERIALS AND METHODS 2.1 SOURCE OF SEEDS Seeds of three varieties of eggplants, African Beauty F 1 (Solanum melongena L.), Kotobi (Solanum aethiopi- cum L.) and Melina F 1 (Solanum melongena L.), were purchased from Technisem ® (Longue-Jumelles, France). 2.2 IRRADIATION OF SEEDS Protocol for the irradiation of eggplant seeds was followed according to the National Institute of Radiation Protection and Research at the University of Ibadan, Ni- geria. The irradiator used was a Gamma-Photon Irradia- tor with model GammaBeam TM X200 (Best Theratronics Ltd., Canada). The samples were irradiated with 100 Gy of gamma rays. 2.3 EXPERIMENTAL SITE AND DESIGN The study was conducted at the University of Cala- bar Teaching and Research Farm, Calabar in two phases – the screenhouse and the field. Completely randomised design with four replications was used for the potted experiment in the screenhouse comprising while ran- domised complete block design with three replications was used in the field. 2.3.1 Screenhouse experiment The top-soil (15–20 cm depth) used for the screen- house experiment was obtained from the earmarked experimental field site. The friable, humus-rich topsoil was properly sieved, uniformly mixed, weighed and then transferred into conically shaped base-perforated plastic Acta agriculturae Slovenica, 119/3 – 2023 3 Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation pots with the following dimensions: 20 cm – height, 8 cm – base radius and 10 cm – rim radius. The total volume of each pot was 5108 cm 3 . Three-quarters of the total vol- ume of each pot was filled with the prepared topsoil (i.e., 3831 cm 3 of topsoil). The potted soil was sufficiently and uniformly wetted with 500 ml of irrigation water the after preparation of the seed bed. The seeds were primed in distilled water for 24 h prior to sowing on 2 March 2020. A total range of 30 seeds were sown in each pot. The total number of pots was 24. Seedlings of irradiated and un- irradiated seeds were raised indoors in potted nursery in the screenhouse. Subsequent irrigation was done for 22 days: at germination (thrice, 50 ml at three days interval) and emergence (thrice, 100 ml at two days interval). At full emergence and growth (≥ 22 days after sowing), 500 ml of the irrigation water was applied at two days interval for three weeks. Transplanting of vigorous seedlings was done at six weeks after sowing (W AS). The seedlings were transplanted at a height of 10–15 cm on 13 April 2020 us- ing the ball-of-earth method. The plant spacing was 0.6 m × 0.6 m and the gross treatment plot size was 2.4 m × 3.0 m (for 20 seedlings) giving a total plant population of 27,777 stands per hectare. 2.3.2 Field experiment The net plot size of 1.2 m × 1.8 m, comprising of six tagged stands of eggplants, was earmarked for growth and yield data collection. Organic fertilizer, poultry ma- nure (15 t ha -1 ), was applied by broadcasting to the soil at two weeks before transplanting. Inorganic fertilizer, NPK 15:15:15 (120 kg ha -1 ), was applied by ring method at 10 cm away from the base of the plants at two weeks after transplanting (WAT). Pest was controlled using a sys- tematic pyrethroid insecticide, Fighter 35 EC (Lambda- Cyhalothrin 15 g l -1 + Acetamiprid 20 g l -1 ). Foliar appli- cation at the rate of 640 ml ha -1 was done at two and four W AT; manual weeding (hand-hoeing and hand-rouging) was done concurrently. Manual harvesting of mature fruits was done between 65 and 95 days after transplant- ing (DAT) (Mahanta and Kalita, 2020). The fruits were hand-picked four times at 10 days intervals. 2.4 DATA COLLECTION Growth and yield data were collected on the num- ber of germinated seedlings that emerged in the screen- house, plant height, number of fully-opened leaves per plant, number of branches (primary and secondary), leaf area according to Rivera et al. (2007), stem width, fruit load (i.e., number of mature fruits per plant), fruit vol- ume based on water displacement method, fruit mass, and fruit yield (per plant and per hectare). 2.5 PROXIMATE ANALYSIS Moisture, crude protein (Kjeldahl method), fat (Soxhlet method), crude fibre and ash contents of the harvested fruits (mean of the four harvests) were deter- mined according to the standard procedures of Asso- ciation of Official Analytical Chemists (AOAC) (2010). Content of carbohydrates was calculated by percentage difference between 100 % (accepted total value of nutri- tional status) and the sum of the moisture, fat, ash, crude protein and crude fibre (Ovenuga, 1986). Calorific value (Kcal 100 g -1 ) was determined from crude protein, crude fat and carbohydrate values accordingly: [(Crude protein × 4.0) + (Crude fibre × 9.0) + (Car- bohydrate × 3.75)] (FAO, 2003). 2.6 DETERMINATION OF ESSENTIAL MINERALS Analysis of essential minerals in fruit samples were performed in three replicates, and data are presented as mean ± SD. Iron was determined following the method of Pearson (1976). Phosphorus was determined by mo- lybdate method as described by Onwuka (2005). Flame photometer was used to determine potassium by the pro- cedure described by Osborne & Voogt (1978). Calcium (extracted by the titrimetric method with EDTA) and Zinc were determined by atomic-absorption spectro- photometry (David, 1958; David, 1959). Magnesium was determined with disodium ethylenediaminetetra-acetate (Smith & McCallcum, 1956) and sodium was determined using ion chromatography (Basta & Tabatabai, 1985). 2.7 DATA ANALYSIS Treatments and replicates mean values of all the nursery and field data obtained were subjected to a two- way analysis of variance (ANOVA) using software Gen- Stat 16 th Edition (VSN International, 2013). Turkey’s Acta agriculturae Slovenica, 119/3 – 2023 4 E. OBOK et al. Honest Significant Difference test (HSD) was used for significant treatment means separation at 95 % confi- dence limit. 3 RESULTS AND DISCUSSION 3.1 RESULTS 3.1.1 Soil physical and chemical properties Soil properties for the two experiments are pre- sented in Table 1. The screenhouse soil texture was sandy loam while the field had a loamy sand soil texture. Soil pH ranged from strongly acidic (4.9) to moderately acidic (5.9). Overall, screenhouse soil had higher cation- exchange capacity (CEC) and base saturation (BS) com- pared to the soil in the field. Both soils were suitable for the cultivation of eggplant. 3.1.2 Effects of irradiation (γ-ray) on growth of egg- plants in the nursery The effects of γ-ray radiation, eggplant variety and their interactions on seedling emergence, height and number of leaves were examined at two and four weeks after sowing (Table 2). At 2 weeks after sowing (WAS), the eggplant variety, Melina F 1 had the highest seedling emergence (p ≤ 0.05) followed by Kotobi and African Beauty F 1 varieties. ‘Kotobi’ was shorter in height (p ≤ 0.05) than ‘Melina F 1 ’ and ‘ African Beauty F 1 ’ . There was no significant difference (p > 0.05) in the average number of leaves for the three eggplant varieties. In general, control (no irradiation) had significantly (p ≤ 0.05) higher effect on seedling emergence and plant height, but no significant (p > 0.05) influenced on the number of leaves borne by each of the eggplant varieties. Following the interaction effect, un-irradiated Melina F 1 eggplant variety had a 100 % seedling emergence while irradiated ‘African Beauty F 1 ’ had the lowest seedling emergence (31.1 %). In terms of plant height, irradiated Melina F 1 eggplant variety was the tallest (4.85 cm) and significantly (p > 0.05) different from irradiated ‘Kotobi’ , the shortest (2.98 cm) eggplant variety. There was no sig- nificant difference in the number of leaves for eggplant × γ-ray interaction effect at 2 WAS. At 4 WAS, single ef- fects of eggplant and γ-ray radiation were significant (p ≤ 0.05) for plant height. γ-ray radiation did not lead to a significant (p > 0.05) variation in the number of leaves. However, the eggplant × γ-ray interaction effect showed that un-irradiated and irradiated ‘Melina F 1 ’ plants were the tallest, similar to irradiated and un-irradiated ‘Afri- can Beauty F 1 ’ , but significantly different (p > 0.05) from irradiated ‘Kotobi’. Meanwhile, the number of leaves ranged from 3.72 (irradiated ‘Kotobi’) to 4.78 (un-irra- diated ‘Melina F 1 ’). All other eggplant × γ-ray effects, ex- cept ‘Melina F 1 ’ , were similar (p > 0.05) to irradiated ‘Ko- tobi’ in terms of the average number of leaves per plant at 4W AS. 3.1.3 Effects of irradiation (γ-ray) on growth of egg- plants in the field The single effects of γ-ray radiation, eggplant vari- ety and their interactions on plant height, stem width, number of branches, number of leaves and leaf area (up- per, middle and lower canopies) were assessed at ten weeks after transplanting to field (Table 3). Varietal effect was only significant (p ≤ 0.05) for leaf area of the upper canopy while radiation effect was significant (p ≤ 0.05) for stem width and number of branches. ‘ African Beauty F 1 ’ had the largest leaves (382.85 cm 2 ) and was not sig- nificantly (p > 0.05) different from those of ‘Melina F 1 ’ (339.75 cm 2 ). Plants from un-irradiated eggplant seeds had thicker stems and more leaves than its counterparts from irradiated seeds. The eggplant × γ-ray interaction only had significant influence on leaf area of the upper canopy of the eggplants. The largest upper canopy leaf area was obtained from irradiated ‘African Beauty F 1 ’ (429.54 cm 2 ) while irradiated ‘Kotobi’ had the lowest up- per canopy leaf area (267.77 cm 2 ). The general observa- tion was that all growth traits of un-irradiated ‘Melina F 1 ’ were consistently higher than its irradiated group. A similar trend was observed for un-irradiated ‘Kotobi’ , ex- cept for leaf area of the middle canopy where the irradi- ated group led with larger leaves. 3.1.4 Effects of irradiation (γ-ray) on yield of egg- plants at harvests Four harvests were made and at each of these har- vests, records were taken on several yield and yield-re- lated characters of the three eggplants varieties obtained from their irradiated and un-irradiated seeds. There were highly significant (p ≤ 0.05) variations observed for all the characters (Table 4). Fruit load (number of mature whole fruits per plant) ranged from 5.5 (‘ African Beauty F 1 ’ and ‘Melina F 1 ’) to 51.5 (‘Kotobi’). Up to the third har- vest, with the exception of Melina F 1, all eggplant varieties from un-irradiated seeds had either similar or higher fruit load in comparison with the irradiated group. At fourth harvest, all irradiated varieties had higher fruit load, ‘ Af- rican Beauty F 1 ’ recorded its highest. Volume and mass Acta agriculturae Slovenica, 119/3 – 2023 5 Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation Table 1: Soil physical and chemical properties pH in H 2 O (1:25) Sand Silt Clay OC TN Available P K + Ca 2+ Mg 2+ Na + Al 3+ H + CEC BS (g kg -1 ) (%) (mg kg -1 ) (cmol (+) kg -1 ) (%) Screenhouse 5.9 690 150 160 2.89 0.24 82.50 0.13 6.2 2.2 0.10 1.16 0.56 10.15 83.00 Field 4.9 843 54 103 1.10 0.14 23.17 0.10 1.4 1.2 0.09 0.56 1.76 5.11 54.59 Table 2: Single and interaction effects of radiation (γ-ray) and variety on growth of eggplants at two and four weeks after sowing in the nursery Treatment Emergence (%) Plant Height (cm) Number of Leaves Plant Height (cm) Number of Leaves Two Weeks After Sowing Four Weeks After Sowing Eggplant African Beauty F 1 46.4 b 4.64 a 2.28 a 7.66 a 4.03 b Kotobi 54.2 b 3.41 b 2.09 a 5.34 b 3.97 b Melina F 1 77.9 a 4.67 a 2.17 a 8.33 a 4.72 a HSD 0.05 <0.01 <0.01 0.14 <0.01 <0.01 γ-ray Irradiation 36.67 b 4.00 b 2.13 a 6.44 b 4.15 a No irradiation 82.32 a 4.49 a 2.22 a 7.78 a 4.33 a HSD 0.05 <0.01 0.03 0.25 <0.01 0.18 Eggplant × γ-ray Irradiated African Beauty F 1 31.1 d 4.52 a 2.22 a 7.16 ab 4.06 bc Un-irradiated African Beauty F 1 61.7 c 4.77 a 2.33 a 8.17 ab 4.00 bc Irradiated Kotobi 25.6 d 2.98 b 2.07 a 4.44 c 3.72 c Un-irradiated Kotobi 82.8 b 3.84 ab 2.11 a 6.24 bc 4.22 abc Irradiated Melina F 1 53.3 c 4.49 a 2.11 a 7.72 ab 4.67 ab Un-irradiated Melina F 1 100.0 a 4.85 a 2.22 a 8.93 a 4.78 a HSD 0.05 0.01 <0.01 0.92 <0.01 <0.01 HSD 0.05 = Tukey’s honestly significant difference test at 95 % confidence level Acta agriculturae Slovenica, 119/3 – 2023 6 E. OBOK et al. Table 3: Single and interaction effects of radiation (γ-ray) and variety on growth of eggplants at ten weeks after transplanting in the field Treatment Plant Height (cm) Stem Width (mm) Number of Branches Number of Leaves Leaf Area (Upper Canopy) Leaf Area (Middle Canopy) Leaf Area (Bottom Canopy) (cm 2 ) Eggplant African Beauty F 1 63.72 a 17.85 a 16.26 a 42.23 a 382.85 a 300.34 a 327.08 a Kotobi 63.00 a 16.95 a 16.51 a 44.56 a 278.65 b 241.82 a 266.44 a Melina F 1 61.93 a 15.00 a 12.53 a 30.56 a 339.75 ab 262.79 a 256.35 a HSD 0.05 0.94 0.11 0.12 0.14 0.02 0.24 0.19 γ-ray Irradiation 60.23 a 15.31 b 13.17 b 33.97 a 339.08 a 275.06 a 277.98 a No irradiation 65.53 a 17.89 a 17.04 a 44.26 a 328.42 a 261.57 a 288.60 a HSD 0.05 0.22 0.03 0.04 0.10 0.67 0.62 0.74 Eggplant × γ-ray Irradiated African Beauty F 1 65.35 a 18.02 a 12.50 a 34.46 a 429.54 a 336.85 a 324.50 a Un-irradiated African Beauty F 1 62.08 a 17.69 a 20.02 a 50.00 a 336.15 ab 263.84 a 329.67 a Irradiated Kotobi 56.16 a 14.38 a 15.06 a 38.43 a 267.77 b 251.25 a 256.61 a Un-irradiated Kotobi 69.85 a 19.51 a 17.95 a 50.68 a 289.53 ab 232.38 a 276.27 a Irradiated Melina F 1 59.19 a 13.53 a 11.94 a 29.03 a 319.93 ab 237.08 a 252.84 a Un-irradiated Melina F 1 64.67 a 16.46 a 13.13 a 32.08 a 359.57 ab 288.50 a 259.85 a HSD 0.05 0.28 0.14 0.29 0.65 0.01 0.21 0.98 HSD 0.05 = Tukey’s honestly significant difference test at 95 % confidence level Acta agriculturae Slovenica, 119/3 – 2023 7 Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation Table 4: Effects of radiation (γ-ray) × variety × harvest interval on yield of eggplants Treatment Combination  Fruit Load Fruit Volume (ml 3 ) Fruit Mass (g) Fruit Yield (kg plant -1 ) Fruit Yield (t ha -1 ) First Harvest Irradiated African Beauty F 1 5.50 i 9.35 ab 505.05 a 2.30 cd 62.55 e Un-irradiated African Beauty F 1 5.50 i 8.15 d 320.05 f 1.55 e 41.72 i Irradiated Kotobi 23.50 d 3.85 j 17.41 r 0.42 ijkl 10.23 q Un-irradiated Kotobi 46.64 b 3.68 jkl 18.23 q 0.69 hi 17.91 n Irradiated Melina F 1 5.50 i 4.92 gh 241.72 n 1.05 f 27.83 k Un-irradiated Melina F 1 7.90 hi 5.31 ef 296.48 k 1.79 e 48.38 g Second Harvest Irradiated African Beauty F 1 5.50 i 9.25 ab 490.05 b 2.45 c 66.71 c Un-irradiated African Beauty F 1 5.50 i 8.85 c 450.05 d 2.15 d 58.38 f Irradiated Kotobi 13.30 f 3.85 j 17.22 r 0.23 l 5.05 t Un-irradiated Kotobi 51.50 a 3.78 jk 15.76 u 0.75 gh 19.49 m Irradiated Melina F 1 11.50 fg 5.05 fg 277.55 l 2.15 d 58.38 f Un-irradiated Melina F 1 5.50 i 4.65 hi 271.30 m 1.03 fg 27.13 l Third Harvest Irradiated African Beauty F 1 5.50 i 9.15 b 450.05 d 2.15 d 58.38 f Un-irradiated African Beauty F 1 9.50 gh 8.81 c 384.05 e 2.95 b 80.60 b Irradiated Kotobi 18.00 e 3.45 l 15.46 v 0.28 kl 6.30 s Un-irradiated Kotobi 36.83 c 3.45 l 16.12 t 0.55 hijk 13.94 p Irradiated Melina F 1 5.50 i 4.95 g 305.05 h 1.15 f 30.60 j Un-irradiated Melina F 1 11.50 fg 4.53 i 186.72 o 1.75 e 47.27 h Fourth Harvest Irradiated African Beauty F 1 17.50 e 8.32 d 318.38 g 4.55 a 125.05 a Un-irradiated African Beauty F 1 8.50 h 9.47 a 480.05 c 4.55 a 125.05 a Irradiated Kotobi 36.17 c 3.51 kl 16.41 s 0.58 hij 14.86 o Un-irradiated Kotobi 21.32 d 3.71 jkl 21.30 p 0.40 jkl 9.90 r Irradiated Melina F 1 11.50 fg 5.37 e 298.18 j 2.38 cd 64.63 d Un-irradiated Melina F 1 10.00 gh 5.52 e 303.26 i 2.15 d 58.38 f HSD 0.05 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 HSD 0.05 = Tukey’s honestly significant difference test at 95% confidence level Acta agriculturae Slovenica, 119/3 – 2023 8 E. OBOK et al. Figure 1: Comparative proximate compositions of γ-ray irradiated and un-irradiated eggplants Acta agriculturae Slovenica, 119/3 – 2023 9 Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation Figure 2: Comparative micronutrient profiles of γ-ray irradiated and un-irradiated eggplants Acta agriculturae Slovenica, 119/3 – 2023 10 E. OBOK et al. of eggplant fruits from irradiated seeds were the highest for ‘African Beauty F 1 ’ up to the third harvest. Fruits of ‘Melina F 1 ’ , from both irradiated and un-irradiated seeds, were significantly (p ≤ 0.05) lighter in mass and smaller in volume than ‘African Beauty F 1 ’. Characteristically, ‘Kotobi’ had higher fruit bearing attribute indicated by its high fruit load but with smaller fruit volume and lighter mass. The average fruit yield per plant ranged from 0.23 kg to 4.55 kg. The highest fruit yield on plant basis was recorded from ‘African Beauty F 1 ’ (irradiated and un-irradiated seeds) at fourth harvest. Fruit yield (plant -1 and hectare -1 ) of ‘Kotobi’ was generally lower than other eggplant varie- ties across the four harvest intervals. ‘ African Beauty F 1 ’ maintained the same trend for fruit yield on per hectare basis. 3.1.5 Effects of irradiation (γ-ray) on comparative proximate composition of eggplants Proximate analysis of freshly harvested fruits of the three eggplants varieties in our study showed that fruits obtained from plants grown from γ-ray irradiated seeds had significantly (p ≤ 0.05) lower moisture content, crude protein, crude fibre, crude fat and ash content (Figure 1). In the other hand, all eggplants fruits from un-irradiated seeds had lower carbohydrate across the three varieties. Fruits of Kotobi variety had the lowest moisture content (70–77 %) followed by African Beauty F 1 (85–89 %) and Melina F 1 (89 – 92 %). Crude protein ranged from 17 % (irradiated ‘Kotobi’) to 28 % (un-irradiated ‘Melina F 1 ’). Irradiated ‘Kotobi’ also had the lowest crude fibre (2.95 %) and crude fat (3.06 %), but had a significantly higher carbohydrate content (71.88 %). Although un-ir- radiated ‘Melina F 1 ’ had the lowest carbohydrate content (55.09 %), its energy value was the highest (385.9 Kcal 100 g -1 ) which was not significantly (p > 0.05) differ- ent from the un-irradiated ‘Melina F 1 ’ (385.72 Kcal 100 g -1 ). Irradiated (378.68 Kcal 100 g -1 ) and un-irradiated (378.88 Kcal 100 g -1 ) fruits of ‘ African Beauty F 1 ’ had the lowest energy values (p > 0.05). Overall, ‘Kotobi’ had the highest ash content (4.72–4.92 %) followed by ‘Melina F 1 ’ (3.61–3.81 %) and ‘ African Beauty F 1 ’ (3.04–3.15 %). 3.1.6 Effects of irradiation (γ-ray) on macro- and micro-nutrients profile of eggplants There were significant (p ≤ 0.05) differences among the three eggplant varieties in micronutrient profiles of fruits obtained from γ-ray irradiated and un-irradiated seeds (Figure 2). In general, un-irradiated Kotobi egg- plant variety had the richest nutrient contents: sodium (47.18 mg 100 g -1 ), calcium (8.11 mg 100 g -1 ), magnesium (14.36 mg 100 g -1 ), phosphorus (21.02 mg 100 g -1 ), potas- sium (196.15 mg 100 g -1 ) and zinc (0.47 mg 100 g -1 ). With exception of zinc (varieties: Kotobi > African Beauty F 1 ≥ Melina F 1 ), the micronutrient profile richness followed the varietis order: Kotobi > Melina F 1 > African Beauty F 1 . It was observed that Na, Mg and K contents followed the same trend in the eggplant fruits for grown from both irradiated and un-irradiated seeds. 4 DISCUSSION The use of gamma ray irradiation on eggplant va- rieties has helped in recent years to induce favourable mutation and improve agronomic attributes of the crop. There are reports that gamma ray could affect the growth and yield of eggplant. Contrary to Zanzibar and Sudrajat (2016) report that gamma ray irradiation could improve seed metabolism and stimulate seed germination, our re- sults consistently showed that seedling emergence in the nursery was however higher from un-irradiated (100 Gy) eggplant seeds of African Beauty F 1, Kotobi and Melina F 1 varieties. In comparison, Rozman (2014) found that the percentage of germination of barley (Hordeum vulgare L.) seeds irradiated with 100 Gy did not differ from the un-irradiated in the first year, it was significantly higher in the fifth year. Also, Suparno (2018) conducted a study on the phenotypic diversity of eggplant (S. melongena L.) resulting from various doses of gamma-ray irradiation (0, 100, 150 and 200 Gy). The results showed that gamma ray irradiation resulted in high significant differences in seedling growth, 100 Gy giving the highest percentage of seedlings emergence (77.5 %) and contrary to our report where we had a range of 31.1 to 53.3 %. However, our results on the effect of gamma ray on plant height of egg- plant (14 and 28 days after planting) grown from irradi- ated seeds was in consonant with Suparno (2018) who reported taller plants from un-irradiated seeds (4.19– 10.45 cm) over 100 Gy irradiated seeds (3.99–10.38 cm). Another study conducted by David et al. (2018) on the effects of gamma irradiation on the agromorphologi- cal traits of two eggplant (S. aethiopicum L.) accessions conforms with our findings which showed reductions in germination percentage (in the nursery) and plant height (nursery and field) at irradiation dose of 100 Gy when compared with plants grown from un-irradiated seeds (control). Although David et al. (2018) had reported that irradiation doses of 40 Gy and 60 Gy were appropriate in creating beneficial agronomic traits in S. aethiopicum L. accessions, these were not consistent between the egg- plant accessions. In support of our findings, Muhammad et al. (2021) reported that the growth, development, and survival rate of Bambara groundnut (Vigna subterranea Acta agriculturae Slovenica, 119/3 – 2023 11 Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M 1 generation (L.) Verdc.) increased with a decrease in gamma-irra- diation. In our study, we also observed similar varietal differences for ‘Kotobi’ (S. aethiopicum L.) in terms of stem width, number of branches, number of leaves and leaf area at different canopy heights in the field. Eggplant fruits have high contents of carbohydrates, proteins and some minerals such as Ca, Mg, and P (Kowalski et al., 2003; El-Nemr et al., 2012) and have low calories (25 kcal 100 g -1 ) (Aly et al., 2019). We reported higher amount of mineral composition in the un-irradiated eggplants group over the irradiated ones. Aly et al. (2019) reported that eggplant growth increased when using a dose of 50 Gy gamma rays while increasing irradiation dose level to 100 Gy reduced phenyl alanine ammonia-lyase (PAL) enzyme and polyphenol oxidase enzyme activities which influences plant growth and invariably its accumulation of some active compounds. Additionally, these enzymes could also have a role in mineral accumulation. Gamma rays are one type of ionising radiation that interact with atoms or molecules to produce free radicals in cells, ac- cording to Aly et al. (2019). These radicals can change essential constituents of plant cells. In contrast to Hus- sein et al. (2012) that treating seeds before sowing by gamma radiation (40–80 Gy) generally increased Na and K in growing damsisa plant (Ambrosia maritima L.) com- pared by its corresponding un-irradiated control, our Na and K contents were higher in un-irradiated eggplants. Also, our results on Ca content in fruits of plants pro- duced from irradiated seeds (except for ‘Melina F 1 ’) was similar to Hussein et al. (2012) for Ca in A. maritima at fruiting even under salinity stress. It was reported that exposure of red radish (Raphanus sativus L.) seeds to gamma irradiation before cultivation improved the root contents of the elements (N, K, S, P, Ca, and Mg) (El- Beltagi et al., 2022). In the study, it was clear that the dose of 100 Gy had different effects on the fruit characteris- tics of eggplants according to the genotypes. For exam- ple, while 100 Gy increased the amount of carbohydrate and energy in ‘Kotobi’ genotype, Ca content increased in Melina F 1 genotype, Zn content increased in African Beauty F 1 genotype. Our research clearly shows that gam- ma-ray irradiation of eggplant is genotype dependent as a technique of producing variation for the generation of new genotypes. Our findings correspond with those of Ulukapi et al. (2015), who discovered inconsistencies in determining optimal gamma radiation dose in eggplant mutation breeding. The preservation, decrease, or in- crease in agromorphological traits, mineral and nutrient compositions of plants grown from irradiated eggplant seeds compared to the control plants made it a problem- atic task to clearly highlight the behaviour of eggplants in response to gamma ray irradiation. Consistent with our study, studies in different plants show that variations in growth and yield traits in response to gamma ray irradia- tion is dependent on the crop variety as well as the radia- tion dose (Rozman, 2014; Majeed et al., 2018; Aparecida Costa Nobre et al., 2022; Puripunyavanich et al., 2022; Saibari et al., 2023) and as such it is difficult to establish a standard dose for mutation breeding in eggplants. 5 CONCLUSIONS Though variations were created, gamma ray irra- diation dose of 100 Gy had inconsistent influences on the agromorphological traits and nutritional profile M 1 generation of ‘African Beauty F 1 ’ (Solanum melongena L.), ‘Kotobi’ (Solanum aethiopicum L.) and ‘Melina F 1 ’ (Solanum melongena L.) eggplant varieties. Plants grown from irradiated eggplant seeds were negatively affected in terms of the following fruit characteristics: fruit load, fruit volume, fruit mass and fruit yield compared to egg- plants grown form un-irradiated seeds. 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