Development and Performance Evaluation of a Spring-Loaded Hand Operated Maize Sheller with Variable Mechanisms

A spring-press, variable mechanism hand operated maize sheller was developed, constructed and tested with corn cobs at 12.6% moisture content, wet basis (w.b) and its shelling performances compared. The machine is lever operated with a spring load-return mechanism and a cob constrictor with changeable shelling mechanisms (spike tooth, rasp bar and star tooth), and a tilted tray for grain collection. The overall dimension of the machine is 520mm x 520mm x 400mm. The machine overall performance is 20.62kg/hr shelling capacity, 85.13% shelling efficiency and 2.13% kernel damage. Comparing the performance of the three shelling mechanisms; rasp bar, spike tooth and star tooth, shelling capacity (16.2, 26.0, 19.67) kg/hr.; shelling efficiency (82.22%, 87.19%, 85.97%); and % kernel damage (0.00, 0.74, 0.51) respectively, the star mechanism has a higher capacity of 26.0kg/hr. The mean kernel damage is higher for star tooth, whereas it is zero for rasp bar. In comparison with conventional hand-palm shelling method (100% shelling efficiency, 13.83kg/hr shelling capacity and 0% kernel damage), the hand operated sheller has a better output capacity, reasonable shelling efficiency but slightly higher kernel damage. By implication, machine performance efficiency does not give a true reflection of how effective a system work until the machine capacity is determined. The sheller ease household shelling maize for consumption with initial low production cost of N13, 100.00 (~$30).

EFFECTS OF POLLEN CONTAMINATION AND KERNEL WEIGHT ON KERNEL STRUCTURE OF MAIZE IN OPEN AND SELF POLLINATION TREATMENTS

In small plot experiments conducted in maize, the mostly used pollination methodsare open and self-pollination treatments. Comparative studies using thesetreatments are abundant in scientific literature; however studies on the effect ofcross pollination and kernel weight on kernel biochemical properties in differenttreatments are limited. In this study, we conducted a comparative experiment toinvestigate the effect of pollen contamination and mean kernel weight on kernelbiochemical composition of ten different maize genotypes by using two differentpollination methods.Open and self-pollination treatments were applied aspollination methods. Eight different traits; kernel weight, cross pollination rate,protein, oil, carbohydrate, oleic acid linoleic acid and carotenoid content weremeasured. Regression analyses were performed to understand the effects of crosspollination and mean kernel weight on biochemical constituents of maize kernel indifferent treatments. Results showed that the major biochemical traits, such asprotein, oil and carbohydrate content were significantly affected by pollencontamination but minor traits were not. When data were combined (n=60) theeffect of pollen contamination in different treatments was not clearly understood.When data (n=30) of each treatment were separately analyzed, it was found thatcross pollination rate had significant effect on the most of biochemical constituentsin open pollination. Overall, results suggested that pollen contamination had aneffect on major biochemical traits in maize and hand pollination could be used forpreventing of unwanted effect of pollen contamination in small plot experiments.However, it should be considered that the effects of hand pollination on kernelweight affect the some biochemical traits in maize.

Phenotypic variation in Pentaclethra macrophylla Benth (Fabaceae) from the humid lowlands of Cameroon

Pentaclethra macrophylla Benth (Fabaceae) has emerged as one of the top underutilized agroforestry species with considerable economic and nutritional value in West and Central Africa where the species is endemic and exploited by farmers. However, the species suffers from a level of exploitation that is unsustainable. This dramatically decreases the natural resource base. Key information such as tree variation is needed to develop an ef cient strategy for its domestication. This study therefore assesses the species phenotypic variation in two populations in the forest zone of Cameroon. Overall, 49 trees (19 in Lomie and 30 in Djoum) were sampled. Tree characteristics (diameter at breast height (DBH), height, crown diameter), pod (number of seeds per pod), seed (width, length, thickness, weight) and kernel traits (weight) were recorded. All these parameters were subjected to a combination of multivariate, PCA and cluster analyses. Results revealed four clusters of P. macro- phylla trees with cluster IV considered as the best because it contains four elite trees (LOM/PM/09, LOM/PM/13, LOM/PM/15 and LOM/PM/16) with desirable tree characteristics. Clusters were further considered as different groups of trees, and seeds and kernel traits variation assessed using ANOVA analysis. Significant differences in mean kernel weight occured between groups. Cluster IV presented the highest mean kernel weight (19.25 ± 0.16 g), while cluster III had the lowest (13.28 ± 0.57 g). Within cluster IV, the highest kernel weight (25.83 ± 5.62 g) was found in tree number LOM/PM/09. Kernel weight was found to be positive and strongly correlated (r = 0.95) with seed weight. We can conclude that there is phenotypic variation between the trees of P. macrophylla in terms of DBH, height, crown diameter, number of seeds, seed width, seed length, seed thickness, seed and kernel weight. Results obtained in this study could serve as a useful guide for the selection of targeted P. macrophylla trees either for domestication or for conservation purposes. Key words: Pentaclethra macrophylla, Ideotype, kernel weight, tree selection, tree variation

Phenotypic variation in Pentaclethra macrophylla Benth (Fabaceae) from the humid lowlands of Cameroon

Pentaclethra macrophylla Benth (Fabaceae) has emerged as one of the top underutilized agroforestry species with considerable economic and nutritional value in West and Central Africa where the spe¬cies is endemic and exploited by farmers. However, the species suffers from a level of exploitation that is unsustainable. This dramatically decreases the natural resource base. Key information such as tree variation is needed to develop an efficient strategy for its domestication. This study there¬fore assesses the species phenotypic variation in two populations in the forest zone of Cameroon. Overall, 49 trees (19 in Lomie and 30 in Djoum) were sampled. Tree characteristics (diameter at breast height (DBH), height, crown diameter), pod (number of seeds per pod), seed (width, length, thickness, weight) and kernel traits (weight) were recorded. All these parameters were subjected to a combination of multivariate, PCA and cluster analyses. Results revealed four clusters of P. macrophylla trees with cluster IV considered as the best because it contains four elite trees (LOM/PM/09, LOM/PM/13, LOM/PM/15 and LOM/PM/16) with desirable tree characteristics. Clusters were further considered as different groups of trees, and seeds and kernel traits variation assessed using ANOVA analysis. Significant differences in mean kernel weight occured between groups. Cluster IV presented the highest mean kernel weight (19.25 ± 0.16 g), while cluster III had the lowest (13.28 ± 0.57 g). Within cluster IV, the highest kernel weight (25.83 ± 5.62 g) was found in tree number LOM/PM/09. Kernel weight was found to be positive and strongly correlated (r = 0.95) with seed weight. We can conclude that there is phenotypic variation between the trees of P. macrophylla in terms of DBH, height, crown diameter, number of seeds, seed width, seed length, seed thickness, seed and kernel weight. Results obtained in this study could serve as a useful guide for the selection of targeted P. macrophylla trees either for domestication or for conservation purposes.

Groat proportion in oats as measured by different methods: Analysis of oats resistant to dehulling and sources of error in mechanical dehulling

Groat proportion is the groat yield from an oat dehulling process. We compared hand, impact and compressed-air dehulling to measure groat proportion, and evaluated sources of error. Hand dehulling was the simplest and most accurate method, because all groats and hulls can be accounted for. Mechanical methods dehulled most, but not all, oat kernels. Failure to account for oats resistant to dehulling in calculations resulted in gross errors. Oats resistant to impact dehulling did not differ in groat proportion from the general population, but differed in many physical properties. Hull structure may account the most for their resistance to dehulling. Mechanically dehulled oats consistently yielded lower groat proportions than those from hand dehulling. Since the difference cannot be attributed to oats resistant to dehulling, groats must be lost during the aspiration process, common to all mechanical methods. Uniform aspiration protocols should provide a uniform error. All groat proportion values obtained here were highly correlated among themselves, except when values were not corrected for oats resistant to dehulling. A theoretical groat proportion calculated from the ratio of the mean groat mass (collected by any means available) and the mean kernel mass yielded a groat proportion value that did not differ significantly from the hand dehulling value.Key words: Oat milling, groat proportion, oat dehulling