Ethnobotanical Leaflets 11: 27-31. 2007.
Growth and Yield of Pearl Millet (Pennisetum glaucum L.R. Br.) As Influenced by Downey Mildew and Smut Diseases in Kabuga Area of Kano State, Nigeria
O.T. Mustapha and Y. Mustapha
Department of Biological Sciences, Bayero University, kano, Nigeria
Issued 14 March 2007
The performance of four Pearl millet varieties comprising three improved varieties and one local variety was investigated in terms of their yield and response to natural infestation of Downy mildew (DM) and smut diseases. Data on yield parameters, disease score and weather were collected over the two year period of the investigation. The investigation revealed the existence of inherent differences among the four varieties tested and the influence of biotic and abiotic factors on some of the yield parameters. The variety ICMN IS 88224 was found to be the most susceptible to DM and smut disease while two improved varieties (ICMn IS series) were found to be tolerant. The local variety, INMV 55 was found to be the most tolerant and as such, ICMN IS 88212 is recommended for this location.
Key Words: Pearl millet (Pennisetum glaucum); Downey mildew disease; Smut disease; Crop performance.
In Africa, Pearl Millet is primarily grown for human consumption serving as the staple food in some of the poorest countries and regions of the continent. The grain is mainly used in three different ways, as a grain like flour (couscous), as a dough and as a gruel (Brunken et. al., 1977; Counting and Harris, 1968).
Despite the enormous uses to which Pearl Millet can be put, there are some constraints which limit the production of the crop in savanna environment of Northern Nigeria. Among these are nature of soils, climate of the region and cultural techniques and management practices. Others are diseases, pests, weeds and other parasites whose effects seriously affect the yield of the crop.
It has been established that Downey mildew and smut are the two most important diseases of the crop in the farmers field and experimental farms in Northern Nigeria (Selvaraj, 1978). It is a fact that the performance of any crop at a particular location depends on the variety and the biotic and abiotic constrains obtainable at that location. This study therefore aims at finding the influence of these two diseases on the growth and yield of four improved varieties of the crop in the chosen location with a view to identify those varieties that are adapted and suited to this location.
Materials and Methods
Three improved Pearl Millet varieties, ICMN IS 88210, ICMN IS 88212 and ICMN IS 88224 were collected from Lake Chad Research institute (LCRI) Maiduguri while the fourth variety, INMV 55, was collected from a local farm in Kano. The investigation spanned over a period of two cropping seasons, 1992 and 1993 seasons, and was conducted at Bayero University Experimental Plot located at Kabuga area of Kano. This location was chosen because it has been used for cropping millet solely over the years and it is naturally infested with causative agents of Downey mildew and smut diseases.
The land was cleared and an area of 25x20 metres was measured and divided into 16 plots. A Randomized Complete Block Design (RCBD) layout with four replicates was used. The area was ridged and the plots were separated by an area of 0.5m. Each plot comprises four ridges with the two central ridges serving as the plot (sampling rows). Each plot was ragged with code number.
The seeds were sown on each ridge. Two weeks after sowing, plants that germinated were thinned to two plants per stand by pulling out the weaker and less developed seedlings. Fertilizer (NPK-27-13-13) was applied basally to all the 16 plots. Weeding was done with hand-held hoe as at when required.
Data were collected on a number of parameters, These include seedlings emergence, seedling establishment, days to 50% flowering, plant height, spike length, spike weight, grain yield per plot, disease score, rainfall and temperature. Grain yield was determined by lightly pounding the spikes from each plot in mortal and followed by removal of the husk. The threshed grains were weighed and the weight recorded as grain yield per plot. Disease score was taken 10 weeks after sowing by counting the number of infest plants by Downey mildew and smut diseases per plot. The data on rainfall and temperature were obtained from the meteorological unit of the Department of Biological Sciences, Bayero University, Kano. The data collected were subjected to statistical analysis, i.e. Analysis of Variance (ANOVA).
Results and Discussion
From Table 1 there is a clear evidence that in the two seasons ICMN IS 88210 and ICMN IS 88224 had higher seedlings emergence value than the other two varieties. Seedling establishment followed the same pattern as seedling emergence as statistical analysis showed no significant difference among the varieties in both years. The differences observed in seedling emergence and seedling establishment shoed that the individual quality of each variety has come into effect despite the underlying environment conditions.
Differences also exist among the four varieties in terms of their time of flowering and the differences have been found to be significant (p < .05). The means show that varieties ICMN IS 88210 and INMV 55 flowered earlier than the other two. On the other hand, the means for yield show that ICMN IS 88210 out yielded the others and it is followed by INMN 55 while the others follow in the order ICMN IS88212, ICMN 88224. This clearly shows that those varieties that flowered earlier recorded higher yields than those that followed later.
Table 1: Mean Values for the effect of Downey mildew and smut diseases on growth and Yield of Pearl Millet.
Table 2: Mean GED and smut Incidence for the varieties.
Table 3: Total Rainfall (mm) during the 1992 and 1993 season.
Table 4: Monthly maximum and minimum temperatures (C) during the 1992 and 1993 seasons.
Variation in plant height also exists among the varieties but the differences are not statistically significant. Varietal differences with respect to spike length have been found to be statistically significant. The results for spike weight clearly showed some correlation with that of spike length for varieties that recorded higher values for spike weight. The data generally agrees with the suggestion that longer spikes tend to be heavier than shorter ones.
Among the factors that influence seedling emergence and seedling establishment are soil temperature and soil moisture content (Gupta et al. 1983). In this investigation, data for temperature and rainfall show striking difference five days after sowing (5 DAS) which was the period when data for emergence as taken. It was inferred from this investigation that the combined effect of low rainfall and higher temperature during 1993 season for the period (5 DAS) could have probably resulted in the low values recorded for all the four varieties while the higher rainfall and lower temperature conditions favoured emergence during the 1992 season. The performance of the four varieties in terms of establishment indicates that plants established better in 1993 due to early rains and rather poorly in 1992 due to the late arrival of rains.
The incidence of downy mildew (DM) during the two seasons shows quantitative differences in the four varieties. ICMN IS 88212 and INMV 55 showed a stable resistance in both season (0% and 6.42%) and (7.25% and 0%) respectively while the other two varieties ICMN IS 88210 and ICMN is 88224 showed an intermediate reaction. This investigation reveals that a variety could be found to be susceptible to S. graminicola in one season but resistant in another and vice versa-as also found in earlier works (ICCRSAT, 1989). ICMN IS 88224 is so far the most susceptible to DM and reflected in its yield (low). However, field tests have revealed a near perfect negative correlation between incidence of DM and grain yield while positive correlation was shown between incidence of DM and straw yield and intensity and straw yield (Mayee and Sirasker, 1982).
Smut disease severity is more in 1993 than in 1992. Even though all the four varieties show intermediate reaction to the disease in the 1992 season, only ICMN IS 88212 maintained such a reaction in 1993 while the other three showed susceptible reaction. It has been found that teleuspores remain viable in soil at depth up to 22.50cm for about one year (ICAR, 1961) and as such it is possible that the three varieties that showed a susceptible reaction in the 1993 season were reinfected by teleuspores of the previous season while the fourth variety could be said to have an inherent intermediate reaction to the disease (Bourke, 1963). ANOVA shows a statically significant difference with respect to year which shows that this investigation agrees with the suggestion that smut severity is influenced by location and year of testing (ICRISAT, 1989). Even though frequent rains particularly during the vegetative period (July September) generally increase disease levels in millet due to continuous cloud cover and reduced solar radiation levels (*ICS< 1988), results from this investigation show a higher disease incidence during the 1993 season.
The result of this investigation has revealed that there are inherent differences among the four varieties tested in flowing and spike length. In general, the check variety, INMV 55, was less susceptible to the disease than the new varieties with ICMN with ICMN IS 88224 recording the highest infestation. It is significant however to the check variety and is therefore desirable for this location. The grain yields obtained from the trials were generally low and no significant differences were found in grain yield either between growing seasons or between varieties. It can therefore be concluded that the plant has compensated for the differences observed in other parameter such that at harvest, the grain yield is not affected by such differences observed in other parameters such that at harvest, the grain yield is not affected by such differences. It must also be noted that most of the factors considered interact to produce effects.
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