Acta agriculturae Slovenica, 116/2, 229–236, Ljubljana 2020 doi:10.14720/aas.2020.116.2.1440 Original research article / izvirni znanstveni članek Influence of plant extracts, storage containers and storage duration on the physiological quality of watermelon (Citrullus lanatus (Thunb.) Mansf.) seeds stored under ambient conditions Tolulope Olaitan KEHINDE 1, 2 , Olatunde Azeez BHADMUS 1 , Joseph OLUFELO 1 Received January 16, 2020; accepted October 05, 2020. Delo je prispelo 16. januarja 2020, sprejeto 05. oktobra 2020. 1 Federal University of Agriculture, Department of Plant Breeding and Seed Technology, Abeokuta, Ogun State, Nigeria 2 Corresponding author, e-mail: kehindeto@funaab.edu.ng Influence of plant extracts, storage containers and storage du- ration on the physiological quality of watermelon (Citrullus lanatus (Thunb.) Mansf.) seeds stored under ambient condi- tions Abstract: Watermelon seed being an oily seed is prone to rapid deterioration of its quality, hence maintaining quality during storage is germane. The study therefore investigated the effect of crude plant powder, storage containers and storage du- ration on the seed quality of two varieties of watermelon seeds. Seed lots each of 100 g of each variety were treated with 10 g of four crude plant powders of clove basil leaf, red chilli pepper fruit, garlic, neem leaf and a synthetic fungicide. All samples were stored in three storage containers (envelope, tin and glass bottle). Treated seeds were stored under ambient conditions for 180 days. Germination and seedling vigour were determined at 180 day time course after storage. Data were subjected to mean separation using Duncan’s Multiple Range Test. Significant dif- ferences were observed in the quality traits examined in wa- ter melon due to differences in variety, seed treatment, storage container and storage period. ‘Kaolak’ was the best in storage in terms of seedling vigour and viability. Glass bottle was identi- fied as the best storage container in maintaining seed quality of water melon throughout the storage period. The use of organic materials especially neem and clove basil leaf powder proved much better for maintaining germinability and seedling vigour and extension of seed longevity than inorganic material. Key words: seed longevity; seed treatment; storage me- dium; probit modelling; seed storage life Vpliv rastlinskih pripravkov, načinov in trajanja shranjeva- nja na fiziološke lastnosti semen lubenice (Citrullus lanatus (Thunb.) Mansf.) shranjenih v ambientalnih razmerah Izvleček: Semena lubenice vsebujejo veliko olja in so zato podvržena hitremu propadu, zaradi česar je njihovo shranjeva- nje oteženo. V raziskavi so bili preučevani učinki zmletih izbra- nih rastlin, načina in trajanja shrambe na kakovost semen dveh sort lubenice. Vzorci semen, vsake od obeh sort lubenice po 100 g, ki so bili tretirani s po 10 g grobega prahu zmletih listov afriške bazilike, plodov rdečega čilija, strokov česna, listov aza- dirahta in sintetičnega fungicida so bili nato shranjeni v treh vr- stah shranjevalnikov in sicer v papirnatih vrečkah, v kositrnih posodah in steklenicah. Tretirana semena so bila shranjena 180 dni v ambientalnih razmerah. Podatki meritev so bili obdelani z Duncanovim multiplim testom. Ugotovljene so bile značilne razlike v kakovosti semen lubenice glede na sorto, obravnava- nje semen, način in trajanje shrambe. Sorta Kaolak je bila po shranjevanju najboljša glede na vitalnost in vigor pridobljenih sejank. Za vzdrževanje kakovosti semen so bile v celotnem ob- dobju shrambe najboljše steklenice. Uporaba rastlinskih pri- pravkov, še posebej prah iz listov azadirahta in afriške bazilike, se je za shranjevanje in vzdrževanje kalivosti semen lubenice kot za vigor sejank izkazala boljše kot sintetični fungicid. Ključne besede: dolgoživost semen; tretiranje semen; na- čin shranjevanja; probit model; dolgoživost shranjenih semen Acta agriculturae Slovenica, 116/2 – 2020 230 T. O. KEHINDE et al. 1 INTRODUCTION Water melon belongs to the genus Citrullus and family Cucurbitaceae (Huxley, 1992). The Cucurbitaceae is a family of medium sized plants, primarily found in the warmer regions of the world. It is recognizable by its pinnatifid leaves and prolific fruition, up to 100 melons on a single vine. The water melon fruit, loosely consid- ered a type of melon, possesses a smooth exterior rind (green and yellow) and a juicy, sweet, usually red, yellow or orange interior flesh (Jeffrey, 2005). Moreover, they are used as a domestic remedy for urinary tract infection, he- patic congestion, catarrh, worm remedy, abnormal blood pressure (Deible and Swanson, 2001; Amadi et al., 2003). Watermelon contains about 6 % sugar and 92 % water by mass. As with many other fruits, it is a source of vitamin C. Seeds of watermelon are considered to have a long- life span in storage as to its quality (Priestley, 1986). In subtropical regions where watermelon seeds are inten- sively produced and where high relative humidity (> 70 %) is often accompanied with high temperature (30- 35 o C), the quality or vigour of the seed can decline dras- tically within 12-18 months (Demir et al., 2011). Seed longevity is greatly influenced by the relative humidity and storage temperature. The indiscriminate use of chemicals and their residual toxicity adversely af- fects the non-target animals and human beings besides affecting the seed quality. Many of the synthetic chemi- cals are effective but they are not readily degradable physically or biologically and yield more toxic residues. However, the use of chemicals is still in use. Hence, a safe and feasible approach is the treatment of seeds with botanicals which are safe, economical, eco-friendly and non-harmful to seed, animal and human beings (Mahesh and Hunje, 2008). W atermelon seed being an oily seed is prone to rapid deterioration of its quality and since seed treatment with botanicals have been found to be more suitable and safe in maintaining viability of seeds (Adebisi, 2012), hence this study therefore will investigate the effects of crude plant powders, storage containers, storage duration on the maintenance of the quality of watermelon seeds. 2. MATERIALS AND METHOD 2.1. SEED MATERIALS Two varieties of watermelon seeds (‘Kaolak’ and ‘Sugar Baby’) were sourced from the Department of Plant Breeding and Seed Technology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria. Seeds were scooped out from freshly harvested mature fruits and air-dried under ambient temperature for 4 weeks. Seed moisture content was thereafter determined using the oven drying method (ISTA, 1995). 2.2. EXPERIMENTAL DESIGN The experiment was factorial laid out in completely randomized design with three replications. There were four factors to be considered; variety, seed treatment, storage containers and storage time. 2.3. METHOD OF SEED TREATMENT The dried seed lots were treated with crude plant powdered treatments following the methods of Adebisi et al. (2013). Seeds were dry-dressed with four organic material which include finely powdered leaves of clove basil (Ocimum gratissimum L.) leaf (10 g 100 g of seed -1 ), red chilli (Capsicum frutescens L.) fruit (10 g /100 g of seed -1 ), garlic (Allium sativum L.) fruit (10 g 100 g of seed - 1 ), neem (Azardirachta indica A. Juss.) leaf (10 g 100 g -1 ) of seed and one inorganic material (Apron plus) while one with no treatment served as the control. Seeds were dressed with recommended doses in sealed plastic containers at room temperature. After treatment, the storage containers were shaken twice daily up to seven days. Thereafter, the seed were stored in three different moisture pervasive materials (galvanized iron tin, glass bottle, and envelope). 2.4. SEED STORAGE The containers with the treated seeds were kept in seed store under ambient conditions (temp 30 ° C, RH 75 %) for 180 days to evaluate the treatment effects on the seed viability and seedling vigour traits. 2.5. QUALITY ASSESSMENT Viability Test: Seed samples were taken from each treatment at 0, 30, 60, 120, 150 and 180 days of storage and was tested for the following seed quality traits. Vi- ability test was carried out in the laboratory. Fifty seeds in three replications were placed inside petri dishes in an incubator and were maintained at 20 ml of distilled water and germination count was taken at 7 days (ISTA, 1995). Seed viability = germination count at 7 days X 100 number of seeds sown Acta agriculturae Slovenica, 116/2 – 2020 231 Influence of plant extracts, storage containers ... of watermelon (Citrullus lanatus (Thunb.) Mansf.) seeds stored under ambient conditions Seedling Vigour Index: Seedling vigour index (SVI) was calculated by multiplying percentage (%) viability by the average of seedling length on the 7th day of germina- tion (ISTA, 1995) and divided by 100. SVI = seed viability (%) at 7 days x seedling length(cm) 100 Seedling Length: Shoot length of 10 randomly se- lected seedlings were measured using a ruler in centime- tre (cm). 2.6. DATA ANALYSIS All data collected were subjected to analysis of vari- ance using Statistical Analysis Software (SAS TM , 2002). Significant means were separated using Duncan’s Mul- tiple Range Test at 5 % probability level (Duncan, 1955). The seed viability data were subjected to probit analysis using the PROC statements of SAS in order to predict the storage life of the seeds. Seed longevity pa- rameters were values of Ki (an estimate of the probit value of initial seed viability at the time of storage), slope (1/σ), an estimate of rate of seed physiological deteriora- tion, sigma (σ), the standard deviation of seed survival curve and an estimate of time taken to lose 1 probit seed viability, and P 50 , a measure of time taken for a seed lot to lose 50 % viability and estimate of absolute seed longevity (Ellis and Roberts, 1980). 3. RESULTS Table 1 presents the effect of plant extract on seed viability of two water melon varieties stored for 180 days under natural ageing condition. From the result, seeds of ‘Kaolak’ treated with neem leaf powder had the highest viability value though statistically similar to values ob- tained in some other treatments at 0 days of storage. At 30 days of storage, ‘Kaolak’ seeds treated with chilli pepper powder gave the highest viability value (94.44 %) though statistically similar to those obtained in some other treat- ments. Treated seeds of ‘sugar baby’ had comparable val- ues among the treatments. A progressive decline was ob- served among all the seeds as storage duration increases with ‘Kaolak’ seeds treated with neem powder still having the highest value among other treatments. The effect of plant extract on seedling vigour of two water melon varieties is shown in Table 2. Seeds of ‘Ka- olak’ irrespective of the treatments had seedling vigour above sugar baby at 0 day of storage. At 30 days of stor- age, seeds of ‘Kaolak’ treated with basil leaf powder gave the highest seedling vigour values though statistically similar to values obtained in some other treatments. It was observed that ‘Kaolak’ seed treated with neem pow- der maintained the highest value throughout the storage duration. Table 3 shows the effect of container and storage time on seed viability of two water melon varieties. Seeds of ‘Kaolak’ stored in envelope had the highest (98.89 %) statistically similar viability value with other containers Variety Treatment Storage Duration (days) 0 30 60 120 150 180 Kaolak Neem 100a 93.33ab 88.89a 88.89a 73.33a 56.67a Clove basil 97.78a 87.78ab 73.33a-e 55.56cd 45.56bc 34.44cde Pepper 97.78a 94.44a 83.33abc 71.11bc 57.78b 41.11bc Garlic 93.33ab 86.67abc 75.56a-d 65.56bc 53.33b 43.33b Apron plus 88.89ab 82.22a-d 71.11b-e 61.11bc 47.78bc 34.44cde Control 97.52a 92.23ab 86.67ab 77.78ab 75.56a 55.66a Sugar Baby Neem 81.11bc 77.78b-e 66.67cde 54.44d 46.67bc 32.22cde Scent leaf 82.22bc 77.78b-e 71.11b-e 60.00cd 44.44bc 27.78cde Pepper 74.44cd 67.78de 60.00de 44.44d 32.33c 20.00e Garlic 81.11bc 77.78b-e 66.67cde 58.89cd 42.22bc 25.56de Apron plus 66.67cd 64.44e 56.67e 44.44d 34.44c 22.22de Control 75.56cd 71.11bc 62.22de 53.33cd 42.22bc 27.78cde Table 1: Effect of seed treatment on viability (%) of seeds of watermelon stored under ambient conditions at different storage dura- tion Means followed by the same letters in each column do not differ significantly at 5 % level of probability according to Duncan’s Multiple Range Test (DMRT) Acta agriculturae Slovenica, 116/2 – 2020 232 T. O. KEHINDE et al. (glass bottle 95.56 % and tin 94.44 %). The same trend was observed at 30 and 60 days of storage. At 120 days of storage, seeds of ‘Kaolak’ stored in glass bottle gave the highest viability value though similar to that of seeds of the same variety stored in envelope. Also, it was observed that, seeds of ‘Kaolak’ stored in glass bottle maintained its viability when compared with other containers through- out the storage duration. In Table 4, the effect of container and storage du- ration on seedling vigour of two water melon varieties. Treated ‘Kaolak’ seeds stored in envelope, glass bottle and tin recorded statistically similar higher values compared with ‘Sugar Baby’ seeds irrespective of the storage con- tainer at 0 day of storage. The same trend was observed at 30 days of storage while at 60 days, treated ’Kaolak’ seeds stored in glass bottle recorded the highest value. Also, ‘Kaolak’ seeds in glass bottle maintained higher vigour as storage period increased compared with other treat- ments. Data in Table 5 presents the probit parameters of seed longevity data after storage for 180 days in two water melon varieties. The intercept values (estimates of initial probit germination and a measure of seed germination before storage) indicate that there were higher values in neem and pepper in both varieties. Intercept vales were generally higher in ‘Kaolak’ for all the treatments than for ‘Sugar Baby’ . The value of slope indicates the speed of deterioration. Differences were exhibited in most cases in the slope values among the varieties, treatments and con- tainers used. The lowest reduction in speed of deteriora- tion (seed longevity) occurred in ‘Kaolak’ with scent leaf treatment in glass bottle (4.53 days), similar observation was recorded in ’Sugar Baby’ with pepper treatment in Variety Treatment Storage Duration (days) 0 30 60 120 150 180 Kaolak Neem 17.16a 19.30ab 16.97ab 13.84a 12.83a 10.74a Clove basil 14.83abc 20.62a 14.86a-d 8.43bc 8.72b 6.77bc Pepper 15.55abcd 20.17ab 17.54a 10.86ab 8.83b 6.13bcd Garlic 15.85a 16.24bcd 12.33cde 10.33abc 8.11bc 6.39bc Apron plus 15.19ab 17.37a-d 12.80b-e 8.12bc 7.14bc 4.98bc Control 15.67a 19.23ab 15.87abc 13.61a 12.43a 9.84a Sugar Baby Neem 11.65cde 15.25cde 12.16cde 10.04abc 7.34bc 4.92b-e Clove basil 11.52cde 16.51bcd 12.14cde 9.73bc 7.85bc 4.92b-e Pepper 11.21de 13.73de 11.08de 7.99bc 5.56bc 3.28e Garlic 12.11b-e 16.24bcd 12.33cde 10.04abc 6.23bc 3.87cde Apron plus 9.57e 11.94e 8.71e 6.56c 5.07c 3.44de Control 11.39cde 13.72de 11.65cde 8.64bc 8.20bc 5.61c-e Table 2: Effect of seed treatment and storage duration on seedling vigour of watermelon varieties Means followed by the same letters in each column do not differ significantly at 5 % level of probability according to Duncan’s Multiple Range Test (DMRT) Variety Container Storage Duration (days) 0 30 60 120 150 180 Kaolak Envelope 98.89a 88.89a 80.56a 71.11ab 58.33ab 41.11b Glass Bottle 95.56a 90.56a 83.89a 76.11a 66.67a 55.56a Tin 94.44a 88.89a 75.00ab 62.78bc 51.67bc 39.44b Sugar Baby Envelope 76.67bc 74.44b 66.11bc 55.56cd 41.67cd 27.22c Glass Bottle 71.11c 67.22b 60.00c 48.89d 37.22d 24.44c Tin 82.78b 76.67b 65.56bc 53.33cd 42.22cd 26.11c Table 3: Effect of storage container and storage duration on viability (%) of watermelon varieties Means followed by the same letters in each column do not differ significantly at 5 % level of probability according to Duncan’s Multiple Range Test (DMRT) Acta agriculturae Slovenica, 116/2 – 2020 233 Influence of plant extracts, storage containers ... of watermelon (Citrullus lanatus (Thunb.) Mansf.) seeds stored under ambient conditions Variety Container Storage Duration (days) 0 30 60 120 150 180 Kaolak Envelope 16.41a 18.76a 16.15ab 11.04ab 11.03a 7.64a Glass Bottle 15.71a 19.19a 16.75a 12.25a 9.64ab 8.35a Tin 14.50a 19.35a 13.56bc 9.31bc 8.36bc 6.44ab Sugar Baby Envelope 11.59b 15.05bc 11.75c 9.72abc 7.26bc 4.79bc Glass Bottle 10.11b 12.88c 10.57c 8.64bc 6.18c 4.03c Tin 12.02b 15.77b 11.71c 8.13c 6.68c 4.20c Table 4: Effect of storage container and storage duration on seedling vigour of watermelon varieties Means followed by the same letters in each column do not differ significantly at 5 % level of probability according to Duncan’s Multiple Range Test (DMRT) glass bottle (4.53 days) while control in glass bottle dete- riorated faster than others (1.07 days). There was increase in seed longevity extension in the two varieties after seed treatments by estimates of seed half-life (P 50 ) and storage life. Higher estimates of seed half-life and storage life after treatments occurred in ‘Kaolak’ than in ’Sugar Baby’ . In ‘Kaolak’ , estimate of seed storage life was the highest in neem in glass bottle (19.24 months) followed by garlic in glass bottle (14.02 months) and control in glass bottle (13.48 months). Apron plus in tin had the lowest storage life value of 7.94 months. All other treatments had storage life of above 8 months. With ’Sugar Baby’ , storage life estimate was also the high- est in neem stored in envelope (11.50 months) followed by garlic in envelope (9.90 months), control in tin (9.72 months) and clove basil in glass bottle (9.50 months). Pepper in glass bottle had the lowest storage life value of 4.38 months while other treatments had storage life of above 5 months. 4. DISCUSSION Seed treatment had been reported to be effective on the improvement of seed germinability and storability (Mandal et al., 2003). In this study, differential responses in seed germination and seedling vigour were observed among the five seed treatments examined suggesting ample opportunity for selection of seed treatment for maintenance of post-storage seed quality in watermelon. This also supports the findings of Adebisi (2012) who re- ported efficacy of nine seed invigoration treatment in the improvement of okra seed. Significant differences were observed in seed germination and seedling vigour after treatments at each storage time investigated, hence the need to pay close attention to seed treatments regardless of storage container and environments used. ‘Kaolak’ seeds dressed with neem powder gave better germination and seedling vigour at the end of 180 days storage. Seeds of ‘Kaolak’ dressed with neem, clove basil and pepper were higher when compared with that of ’Sugar Baby’. Also, ‘Kaolak’ seed dressed with neem powder still recorded a value of seed germination above 50 % at the end of 180 days of storage. Also, at the end of the storage (180 days), seed treated with the organic invig- oration treatments had maintained greater germination over the inorganic (apron plus). On the mode of action of the crude plant material treatments, various possibili- ties have been reported earlier (Basu, 1994, Manda et al., 2003). In the present study, crude plant extract materials were selected based on previous study (Adebisi, 2012) for the possible effectiveness in controlling free radicals re- actions as antioxidants, antioxidant-synergist and radia- tion protective agents (Slater, 1972, Brand et al., 1994). Capsaicin which is an important constituent of chilli (Capsicum frutescens) fruit has been reported to be an inhibitor of lipid peroxidation (Manda et al., 2003). Lin- alool, allicin, and azadirachtin, the most active ingredi- ent in clove basil, garlic and neem leaves might act as in- hibitors of lipid peroxidation thereby partly responsible for the longevity maintenance of stored seeds. The result revealed significant differences among the two varieties for seed germination and seedling vig- our index when stored for 180 days. ‘Kaolak’ had the best seed germination values during and at the end of the storage. This could be due to differences in genetic constitution of the two varieties evaluated. Differential responses in seed germination and vigour among varie- ties of crop species with and without treatments in stor- age have been reported. (Daniel et al., 2012; Adebisi et al., 2012, Kehinde et al., 2019). On the effect of storage time, seeds treated with neem consistently recorded better seed germination at each storage time investigated. Also, storage of clove basil and pepper powder treated seeds maintained great- er seedling vigour at each of the storage time examined. Higher deterioration of seed quality irrespective of in- vigoration treatments have been reported earlier in dif- Acta agriculturae Slovenica, 116/2 – 2020 234 T. O. KEHINDE et al. Variety Treatment Container K i 1/σ σ P 50 **Seed Storage Life (Months) Kaolak Neem Glass Bottle 6.30 -0.24 4.21 9.62 19.24 Tin 2.26 -0.40 2.51 5.71 11.42 Envelope 1.90 -0.34 2.90 5.51 11.02 Apron plus Glass Bottle 1.46 -0.29 3.45 5.05 10.10 Tin 1.22 -0.31 3.24 3.97 7.94 Envelope 2.22 -0.42 2.37 5.26 10.52 Control Glass Bottle 2.28 -0.93 1.07 6.74 13.48 Tin 3.59 -0.58 1.71 6.14 12.28 Envelope 2.00 -0.32 3.12 6.24 12.48 Garlic Glass Bottle 1.80 -0.26 3.89 7.01 14.02 Tin 1.60 -0.36 2.73 4.39 8.78 Envelope 1.90 -0.37 2.68 5.09 10.18 Pepper Glass Bottle 1.81 -0.30 3.33 6.04 12.08 Tin 2.40 -0.47 2.11 5.07 10.14 Envelope 3.29 -0.61 1.61 5.31 10.62 Clove basil Glass Bottle 1.82 -0.22 4.53 6.18 12.36 Tin 1.91 -0.42 2.37 5.22 10.44 Envelope 1.48 -0.30 3.34 4.39 8.78 Sugar Baby Neem Glass Bottle 1.60 -0.36 2.80 4.49 8.98 Tin 0.76 -0.24 4.24 3.12 6.24 Envelope 1.57 -0.27 3.66 5.75 11.50 Apron plus Glass Bottle 0.86 -0.24 4.07 3.49 6.98 Tin 0.77 -0.23 4.41 3.43 6.86 Envelope 0.78 -0.26 3.81 2.97 5.94 Control Glass Bottle 0.69 -0.23 4.33 2.98 5.96 Tin 1.51 -0.31 3.21 4.86 9.72 Envelope 1.02 -0.24 4.07 4.17 8.34 Garlic Glass Bottle 0.95 -0.20 3.81 3.60 7.20 Tin 1.47 -0.35 2.87 4.21 8.42 Envelope 1.71 -0.34 2.89 4.95 9.90 Pepper Glass Bottle 0.48 -0.22 4.53 2.19 4.38 Tin 1.84 -0.42 2.33 4.30 8.60 Envelope 1.07 -0.31 3.21 3.44 6.88 Clove basil Glass Bottle 1.16 -0.24 4.08 4.75 9.50 Tin 1.15 -0.28 3.57 3.51 7.02 Envelope 1.05 -0.27 3.64 3.82 7.64 Table 5: Results of probit modelling of seed longevity data in two water melon varieties after crude plant treatment and storage in different containers under ambient conditions Ki – intercept, 1/σ- slope, σ- time taken for seed lot to lose 1 probit viability *P50 – seed half-life in days ** Seed storage life estimated as P50 value multiplied by 2 then divided by the 30 days of a month Acta agriculturae Slovenica, 116/2 – 2020 235 Influence of plant extracts, storage containers ... of watermelon (Citrullus lanatus (Thunb.) Mansf.) seeds stored under ambient conditions ferent crop species (Ajala and Adebisi, 2005; Adebisi and Oyekale, 2005). In the present study, gradual decline in seed germination and seedling vigour level was observed irrespective of the pre-storage seed treatment materials with advance in storage times and became pronounced at 180 days (6 months) of storage. Higher seed germination and vigour were maintained at 30 to 150 days of storage. The sharp decline could be due to the deteriorative pro- cesses which were enhanced by the higher temperature (30 º C) and relative humidity (75 %) under tropical humid conditions. With respect to storage containers, ‘Kaolak’ seeds stored in glass bottle consistently gave higher germination and seedling vigour values. This finding conforms to ex- pectation as seeds stored in air tight containers maintain seed qualities longer than non-air tight packaging mate- rials like envelopes which absorb moisture from the sur- rounding atmosphere. This finding agrees with the report of Kumar and Singh (1983) that the seeds of sesame stored in glass bottles maintained satisfactory germination throughout storage period while seeds stored in gunny bags lost viability after six months of storage. Majhi and Bandopadhyay (1993) also reported that freshly harvested groundnut seeds dried to moisture content of 9 % stored in glass bottles for one to nine months had the highest seed viability, root and shoot length and seedling dry mass when compared to seed stored in paper and cloth bag. On probit modelling, the result showed that the wa- ter melon seeds deteriorated at different rate, irrespec- tive of the invigoration material and storage container in which it is been stored for a period of 180 days. ‘Kaolak’ seeds dressed with neem and stored in glass bottle had the highest estimate of storage life (19.24 months) followed by ‘Kaolak’ seed treated with garlic in glass bottle (14.02 months) and control in glass bottle (13.48 months) while ’Sugar Baby’ treated with pepper in glass bottle had the lowest storage life value of 4.38 months. In other words, the PROBIT modelling predicted that ‘Kaolak’ seeds can be stored for an average of 19 months if the seeds are put under good storage conditions. Authors like Adebisi et al. (2003, 2008), Esuruoso (2010), Adebisi and Oyekale (2005), Oni (2012) and Kehinde (2018) have also utilized probit modelling to predict storage life of soybean, rice, kenaf, okra, and sesame, respectively under ambient hu- mid storage conditions. 5. CONCLUSIONS Differences were observed in the two seed qual- ity traits examined in water melon due to differences in variety, seed treatment and storage period. ‘Kaolak’ was the best in storage in terms of seedling vigour and viabil- ity. The use of organic materials especially neem leaf and clove basil leaf powder proved much better for maintain- ing germinability and seedling vigour and extension of seed longevity than inorganic material. 5.1. RECOMMENDATION The findings from this study showed that mainte- nance of seed quality in watermelon using crude plant powders is advantageous in the humid tropical condi- tions. Therefore, since these seed crude plant materials utilized for treating watermelon seeds are cheap, readily available and environmental friendly, these findings will be of benefit to small and medium scale investment in- volved in seed production in Nigeria, where resources for cold storage are scarce. 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