Laboratory experiment was conducted to assess the efficacy of different storage methods of maize grains in Ibadan (a humid tropical ecology) between year 2002 and 2003. The results shows that storage methods (SM), treatment (Tr), SM x Variety (V) and Tr x V interactions were highly significant for numbers of undamaged maize grains (

Akinlosotu, TA

Olakojo, SA

English

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 African Journal of Biotechnology Vol. 3 (7), pp. 362-365, July 2004     Available online at http://www.academicjournals.org/AJB ISSN 1684–5315 © 2004 Academic Journals            Full Length Research Paper  Comparative study of storage methods of maize grains in South Western Nigeria  S. A. Olakojo* and T.A. Akinlosotu  Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M.B.5029, Moor Plantation. Ibadan, Nigeria  Accepted 7 April 2004  Laboratory experiment was conducted to assess the efficacy of different storage methods of maize grains in Ibadan (a humid tropical ecology) between year 2002 and 2003. The results shows that storage methods (SM), treatment (Tr), SM x Variety (V) and Tr x V interactions were highly significant for numbers of undamaged maize grains (P<0.05). Second order interaction  (SM x Tr x V) was highly significant for undamaged maize grains, while first and second order interaction were also highly significant for initial kernel weight, kernel  weight loss, remained kernel weight (RKW), percentage weight loss, tolerance level, as well as number of insects pest responsible for the damage.  Key words: Storage method, Remain kernel weight, Tolerance level, storage treatment.   INTRODUCTION  Insect pests are one of the major organisms that are responsible for decline in quantity, quality and germination potential of maize seeds in storage. Adequate and effective storage of maize grains is therefore a major research thrust for enhanced maize productivity in order to reduce the huge economic loss. Similarly, Boxall (1998) reported that common strategy in many African countries is to sell maize grains immediately after harvest, to avoid losses to insect pests. Although, in traditional storage system, losses are usually well contained at about 5% (Tyler and Boxall 1984), National Stock Product Research Institute (1988) reported an effective maize storage using fumigated maize, stored in gourds for a period of ten months as against non-fumigated maize, stored in similar containers, but, were badly damaged three months after. Birkinshaw and Hodges (2000), on the other hand reported a high degree of protection in mud silo and    *Corresponding author. E-mail Saolakojo@softhome.net or Saolakojo@yahoo.co.uk. traditional cob-storage structures when pesticides application is reduced by 50 and 80% respectively.  Reports from Zimbabwe have demonstrated the value of diatomaceous earth as alternative grain protectant to organophosphate insecticides for sorghum, maize and cowpea. It was also observed to be effective as the conventional insecticides for a period of 40 weeks (Stathers, 2000). The objectives of this study therefore were (i) to evaluate the efficacy of different storage methods of maize grains (ii) and, to recommend suitable storage methods for maize stake holders especially in South western humid environment of Nigeria.   MATERIALS AND METHODS  A laboratory experiment was set up to investigate the efficacy of various storage methods of maize grains using different containers under different treatment effects. The trial which lasted for 12 months (September 2002-2003) was designed as a factorial experiment with two treatments (Phostoixn and non-Phostoxin effects). Three maize varieties (DMR-LSR-W, DMR-LSR-Y and Local maize variety as check), four storage methods (Tin, Nylon bag, Plastic containers and earthen clay pots) resulting in the following twenty four treatments:  Olakojo and Akinlosotu         363         Table 1. Agronomic parameters of maize under various storage systems.   Source of variation Df Number of seed damaged % weight loss % tolerance level No of insect responsible for damage Storage method (SM) 3 6.36** 4.16** 6.40** 9.83** Treatment (Tr) 1 18.64** 26.96** 13.83** 62.61** Variety (V) 2 25.98** 26.29** 21.30* 66.54** SM x Tr 3 1.92 4.69** 1.84 7.71** SM x V 6 3.10** 5.09** 2.89** 6.32** Tr x V 2 29.44** 20.69** 23.32** 59.01** SM x Tr  x V 6 5.14 5.45** 5.55** 8.50** Error 48 4.76 1.09 5.00 0.12 Total 74      *,** Significant at P<0.05 and 0.01 respectively. SM: storage method. Tr: treatment. V: variety.   TP Y: Tin container with phostoxin and yellow seeded maize. TPoY: Tin container without phostoxin having yellow seeded maize. TP W: Tin container with phostoxin and white seeded maize grains. TPoW: Tin container without phostoxin having white seeded maize. TPC: Tin container with phostoxin and with local maize variety. TPoC: Tin container without photoxin having local maize variety.  The other eighteen treatments were coded in similar manner by substituting pl for plastic container, N for Nylon container, and E for earthen pots. P and Po similarly denote phostoxin and non-phostoxin treatment effects, While Y and W represents yellow and white maize seeds respectively (Table 2).  Each container consists of 100 non-infested clean maize grains. The trial was replicated four times and was arranged in a randomized complete block design. The containers were placed on the benches of the Seed Testing Laboratory of the Institute of Agricultural Research and Training (IAR&T), Ibadan at room temperature.  The following data were taken from each of the treatment on monthly basis and were pooled for statistical analysis: Number of seed damaged by pests, weight loss (%), percentage pest tolerance (%) (by counting number of undamaged seed from non phostoxin treatment), and number of insect pest responsible for the damage.  Data were subjected to statistical analysis using SPSS package for the analysis of variance (ANOVA), while separation of pertinent means were done for the significant parameters.  First and second order interactive means were computed to determine the level of interaction among the significant factors. Similarly, Pearson correlation coefficients of maize seed parameters were computed to determine relationship among these factors.   RESULTS AND DISCUSSION  The results from ANOVA showed that storage method (SM), treatment (Tr), as well as storage method x variety (V) and treatment x variety were highly significant for number of maize grain damaged and number of undamaged maize grains (P<0.05). Similarly, second order interaction (SM x Tr x V) was also highly significant for number of undamaged seeds (Table 1). Storage method, treatment, and variety as well as their first and second order interactive means were also highly significant for kernel weight loss, showing differences in the reaction of treatment effects on maize grain parameters. These sources of variation (SM, Tr and V) as well as the first and second order interactions were also highly significant for weight loss, tolerance level as well as number of insect pests responsible for the damage, suggesting their influence on grain weight or losses during storage. SM x Tr was however not significantly different for tolerance level (Table 1), suggesting that pest tolerance level was not directly influenced by storage methods or treatments, but might be genetically controlled. Number of seed damaged recorded means of 12.20 while TPoW, TPoC, PlPoC, and EPoC (with means of 34.0, 100.0, 66.30 and 58.33) were markedly different from one another (Table 2). Numbers of undamaged maize seed were also significantly different from one another. Initial kernel weight differed significantly between varieties.  Kernel weight loss was not significantly different in almost all treatments (0.29 to 3.67%) except TPoC and PlPoC which differed significantly from all others with means of 13.44 and 11.07%, respectively. TPY, TPoY and TPW differed significantly from others probably showing superiority of the DMR-LSR-W and DMR-LSR-Y over other varieties tested, much so that DMR-LSR-Y maize stored in tin without phostoxin weighs as much as those treated with phostoxin. The three treatments weighed 25.56, 26.34 and 25.54 g respectively after storage (Table 2). Percentage tolerance in all treatments were generally high (92.33 and 100.00%) except for TPoW, PlPoC and EPoC with tolerance levels of 66.00, 33.33 and 62.67% respectively (Table 2).   Weight loss was positive and only significantly correlated with number of insect responsible for damage( r=0.93**) and % weight loss (0.99**), while it was  negative and significantly correlated with number of insects responsible for the damage (r=-0.75**, -0.76**). Percentage weight loss, however, was positive and significantly correlated with number of insect responsible for damage (r=0.93**) and negatively correlated with tolerance level  (r=-0.76*).   Prakash  et  al.  (1985) earlier   364         Afr. J. Biotechnol.           Table 2. Means of seed agronomic characters for storage method x treatment x variety interaction.  Treatment No of seed damaged No of  undamaged seed  Initial kernel weight (g) Kernel eight loss (g) Remain kernel eight (g)  % weight loss Weevil tolerant level No of insect responsible for loss TPY 1.33a 98.67a 25.85bcdef 0.29b 25.56ab 1.11c 98.67a 0.67c TPoY 1.67d 98.33a 27.20b 0.86b 26.34a 3.16c 98.67a 0.33c TPW 1.67d 98.33a 25.15cdefgh 0.93b 24.22abcde 3.70c 98.33a 1.33c TPoW 34.00c 66.00b 24.07h 0.53b 25.54abcde 2.21c 66.00b 0.67c TPC 1.67d 98.33a 24.74efgh 0.75b 24.00abcde 3.01c 98.33a 0.67c TPoC 100.00d 0.00d 24.8.defgh 13.44a 14.78f 54.09a 2.13d -2.00a PlPY 0.33d 99.67a 25.86bcdef 1.24b 24.61abcd 4.75c 99.66a 0.001c PlPoY 2.67d 97.33a 24.44gh  1.34b 23.10cde 5.59c 96.67a 2.00c PlPW 3.33d 96.66a 24.44gh 1.34b 23.10cde 5.59c 96.67a 2.00c PlPoW 1.33d 98.67a 25.64cdefg 0.75b 24.89abcd 2.92c 98.67a 0.67c PlPC 0.33d 99.67a 24.43gh 0.79b 23.63bcde 3.22c 99.67a 0.33c PlPoC 66.67b 33.33c 27.07b 11.07a 15.99f 41.00b 33.33c 19.00a NPY 1.33c 98.67a 25.15cdefgh 0.15b 24..98abcd  1.54c 98.67a 1.00c NPoY 1.33d 98.67a 26.14bcde 1.50b 24.63abcd 5.75c 98.67a 1.00c NPW 0.33d 99.67a 24.02h 0.50b 23.45bcde 2.37c 99.67a 1.00c NPoW 1.00d 99.00a 25.39cdefgh 0.17b 25.22abc 0.68c 99.00a 1.00c NPC 1.00d 99.00a 24.02h 0.40b 23.62bcde 1.67c 99.00a 0.33c NPoC 3.33d 97.33a 26.22bcd 2.40b 23.62bcde 9.07c 96.67a 2.67c EPY 0.00d 100.0a 26.13bcde 1.34b 24.79abcd 5.11c 100.0a 0.0c EPoY 7.67d 92.33a 26.35bc 1.53b 24.8abcd 5.80c 92.33a 1.00c EPW 0.33d 99.67a 25.34cdefg 1.47b 23.87bcde 5.79c 99.67a 0.33c EPoW 1.00d 99.00a 28.64c 3.67b 24.97bcd 12.39c 99.00a 1.0c EPC 2.67a 97.33a 2.63fgh 2.47b 22.16e 9.74c 98.00a 1.33c EPo C 58.33bc 62.67b 26.03bcdef 3.47b 2.55de 13.34c 62.67b 9.33b Means 12.22 88.68 25.56 2.19 23.59 8.48 88.68 2.69 SE 8.73 8.95 0.42 1.06 0.71 0.71 4.17 8.95 1.31             Figures not followed by the same letter(s) in the same column are significantly different from one another.               Table 3. Correlation coefficients of seed agronomic parameters under different storage methods.   No of seed damage % weight loss % tolerance level No of insects responsible for damage Kernel Wt (8 WA) - -0.22 -0.28* 0.17 -0.32** No of seed damaged  - 0.75** -0.79** 0.85** % weight loss   - 0.76** 0.93** % tolerance level    - 0.83* No of insects responsible for damage     -                 *, ** Significant at P< 0.05 and 0.01 respectively.   reported that kernel hardness in rice and ratio of length and breadth of grain were positively correlated with the number of adult insects emerged, and, rice grain damaged. This shows the importance of some seed agronomic traits such as length, breadth and texture for tolerance to storage pests. It also implied that, the more damage suffered by maize grains the higher the % weight loss.  Tolerance level was negatively correlated with number of insects’ pest responsible for the damage (Table 3). Farmers in the sub-saharan Africa generally store their unhusked maize on wooding post. Thapa and Dhakal (1997) estimated 11-25% grain loss due to storage pests using this system. This probably suggests the  need  for  cheaper,  more   effective   and   affordable       storage methods that may give higher value to stored maize grains. Generally, kernel weight loss was less than 5% in almost all treatments except TPC, PlPC and EPY with kernel weight loss of more than 10%. TPC and EPC suffered % seed damage of between 40 and 100%. Any of the storage container used in this study appears good for maize storage especially under fumigation. The use of tin, plastic and earthen pots in storing local maize variety without fumigation should be discouraged. On the other hand, post-harvest handling of local maize varieties should be improved to enhance grain quality.   ACKNOWLEDGEMENT  The contributions of the following technical support staff are dully acknowledged. Mr J.A. Ayanwole and Mrs V.I. Obasemola. Olakojo and Akinlosotu         365    REFERENCES   Birkinshaw I,  Hodges R (2000). Improving IPM approaches for IGB control in Africa. PhAction News No3. Boxall RA (1998). Grains post-harvest loss assessment in Ethiopia. Final report NRI Report No 2377. Chatham, U k, Natural Resources Institute 44 p. Boxall RA (2001). Post –harvest technology of quality protein maize, processing and storage- choosing the right technology. In a paper presented in National maize workshop held in IAR, Zaria, 4-5 September, 2001. Stathers T (2000). Use of diatomaceous earths in tropical small-scale grain storage. PhAction No 2. Tyler P, Boxall RA (1984). Post–harvest loss reduction programmes: A decade of activities: What consequences? Tropical Stored products Information 50: 4-13.  National Stored Product Research Institute (NISPRI) 25th Annual Reports, 1989. Prakash A, Pasalu IC, Mathur KC ( 1985). Varietal resistance of stored paddy grains to Stotroga celealella Oliv   Oryza 20: 133-137. Thapa RB, Dhakal DD (1997). Loss of maize grains due to rats and insect pests in storage. Nepalese Journal of Agriculture 18: 73-76.     

Comparative study of storage methods of maize grains in South Western Nigeria

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Comparative study of storage methods of maize grains in South Western Nigeria

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