Journal of Climatology & Weather Forecasting

Adaptation to Climate Change Impacts for Maize Production in Forest-Savannah Agro-Ecological Zone of Nigeria

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Introduction

Climate change is defined as a difference over a period of time (with respect to a baseline or a reference period) and corresponds to a statistically significant trend of mean climate or its variability, persistent over a long period (e.g. decades or more). Climate change is often used to describe any kind of change in climate that may be natural or humaninduced [1]. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years. Climate change is now household word all over the world. Everyone knows that something has gone amiss with the world's weather and climate patterns. Climate variability and change have a direct, often adverse influence on the quantity and quality of agricultural production. Climate change and its implications on human existence have remained a great challenge for agricultural production across the globe. Sub-Saharan Africa has been reported to be one of the most susceptible and vulnerable regions to climate change [2]. Onset Of Rainy Season (ROD) as the beginning of the first 10-day period with cumulative rainfall of greater than or equal to 30 mm one of which is at least 10 mm and followed by another two 10- day period each with at least 8 mm-10 mm rain [3, 4]. Cessation date of rainfall is the postulated period when the condition such as soil moisture availability is below 50% requirements of the plants need. It is determined when the available water content at the root zone has dropped to 50% length of the growing period also called Frost-Free Season can be seen in two ways. One is to enumerate the days of the years when the average temperature is above the threshold at which crop will germinate and continue to grow and the other can be stated in terms of frost-free days, that is, the average number of days between the frost of spring and the frost of fall or winter [4].

Maize has been in the diet of Nigerians for centuries and it is a versatile crop on which many agro-based industries depend as raw materials. For many people and civilizations, maize has since ancient times been a food, feed, commodity, construction materials, fuel, medicine, or decorative plant. Its grain, stalk, leaves, cobs, tassels, and silks have commercial values in most settings, though that of the grain is the greatest. With industrial development, it is increasingly becoming an industrial raw material for the production of starch, gluten, oil, flavor, grits, alcohol, and lingo-cellulose for further processing into a whole range of products and by-products. Planting dates play important roles in the growth and yield of maize. Optimum planting dates have become a prime importance strategy in adapting to the negative impacts of climate change. Therefore, this study is aimed at investigating the optimum planting date as a form of adaptation strategies to climate change impacts on maize production in the forest-savannah agroecological zone of Nigeria.

Material and Methods

Study area

This research was conducted during the growing season of 2021 at the Agro-meteorology research farm of the Federal University of Technology Akure, Nigeria (70- 15’ N, 50 15’E) and project farm of the Institute of Agricultural Research and Training (I.A.R&T.) Ibadan, Nigeria (70 22‘N; 3030‘E) [2]. Both stations are within the Forest-Savannah ecoclimatic zone of Nigeria. The Forest-Savannah eco-climatic zone of Nigeria covers a total land area of about 115,000 km2 . Rainfall in the zone can be described as humid to sub-humid tropical with distinct dry and wet seasons. There are two rainfall peaks in June and September with a dry spell in August (August break) which produces the bimodal rainfall pattern. It is characterized by minimal fluctuations, usually less than 5o C throughout the year. The mean monthly temperature ranges between 28o C and 35o C for 10 years, while the mean monthly minimum temperature ranged between 22.6o C and 26.7o C. February and March have the highest evaporation rate, and it is as high as 6.9 mm. The least evaporation rate (1.6 mm) is recorded in June/July. The relative humidity ranges from 64.5% in February to 91% in June. Soil sampling was carried out before land preparation to quantify the baseline nutrient status of the soil before the trial. The result of the pre-planting soil analysis indicates soil pH of 4.76 and 5.12 for Akure and Ibadan respectively. The percentage of organic matter and organic carbon of the soils in Akure and Ibadan are 13.2%, 1.28%, and 8.9%, 1.04% respectively. The exchangeable bases Ca (1.50 cmol kg-1) and cation exchange capacity (3.26 cmol kg-1) was found in Akure soil, while Ca (1.52 cmol kg-1) and cation exchange capacity (4.02 cmol kg-1). The textural class of the soil in both sites is sandy-loam (Table1).

Table 1. Result of preliminary soil analysis.

Treatment, experimental design and data analysis

The treatments will consist of 3 varieties of maize. The experiment was laid out in a split-plot design with varieties of crops as the main plot and dates of planting as subplot treatment. The treatment combinations were replicated 3 times in each location. Before planting, soil samples shall be obtained at each location from 0 cm-100 cm depth at 20 cm intervals to determine the basic physical and chemical characteristics of the soils (Table 1). Minimum tillage was employed as a means of soilwater conservation. The varieties of maize used are Oba Super 4 (V1 ), ART98/SW1 (V2 ), and Ife Maize hyb-07 (V3 ). The planting spacing of 25 cm × 75 cm crop was followed. The three planting dates selected are 28th June (D1 ), 12th of July (D2 ), and 26th of July (D3 ) in both locations. Three seeds per hole were planted which were later thinned to two per stand at one week after planting. Weeding was carried out manually using hoe two weeks after planting and subsequently at two weeks intervals. Spraying with insecticides at the rate of 4 ml per liter of water was carried out two weeks after planting and at two weeks intervals to prevent the attack of armyworms on the crops. NPK 15:15:15 fertilizer was applied at the rate of 40 kg/ha at basal and at 50 days after planting. The growth and yield data include plant height, number of leaves, leaf area, cob length, cob diameter, 100-grain weight, and grain yield per hectare. The data sets were subjected to descriptive statistics as well as analysis of variance irrespective of the year of planting. The means of the different treatments were separated using Duncan Multiple Range Test (DMTR) (SAS 2002).

Result and Discussion

Table 1 shows the effects of planting dates on the growth characteristics of maize. No significant difference was noticed on the number of leaves and plant height first 10 days of planting. Generally, the growth parameters of maize decreased with delayed planting irrespective of the variety and location of planting. Maize planted at the onset of rain (D1 ) was discovered to have the highest growth parameters. Growth parameters of maize planted on July (D3 ) were shown to have the least characteristics. The results of the effects of planting dates on maize growth characteristics are in conformity with the findings of Adetayo et al., (2008) who reported that the growth parameter of maize was reduced with delayed planting [5].

Results from the Table 2 revealed that planting dates had significantly affected the cob length of maize. Length of cobs decreased as the planting was delayed. Plots sown on June 28, 2021, recorded maximum cob length followed by plots seeded on July 12, 2021, while minimum cob length was observed in plots sown on July 26, 2021, irrespective of the variety and location of planting. These results are quite in conformity with the findings of Bello (1996) who reported that cob length decreased with delay in planting. It was shown in Table 3 that planting dates had a significant effect on cob diameter. A decreasing trend was observed in cob diameter with delay in planting dates. Although the decreasing trend was observed in 100-grain weight with delay in planting date, the difference is minimal. The heavier grains with earlier planting might be due to prolonged growing and grain filling periods which enabled the plants to produce bold and plump grains. These results are in agreement with the findings of [5, 6]. who reported a reduction in 1000 grain weight with a delay in planting dates. It was further shown in table 3 that grain yield was significantly affected by planting dates. Crops planted on June 28, 2021, recorded maximum grain yield followed by crops planted on July 12, 2021, while minimum grain yield was observed in crops sown on July 26, 2021 [7]. These results are in line with the results of Aziz et al, (2000), Kim et al. (1999), and Cantarero et al, (2000) who reported that the grain yield of maize decreased with delay in planting dates [6,8-10].

Table 2. Growth performance of three selected varieties of maize at different dates in Akure and Ibadan

Table 3. Yield performance of three varieties (Var.) selected of maize at different dates during in Akure and Ibadan.

V₁ - Oba Super 4, V₂ - ART98/SW1, V₃ - Ife Maize hyb-07, D1 - 28th June, D2 - 12th of July, D₃ - 26th of July, L1 -Akure, L₂ - Ibadan, DAP- Days After Planting.

Conclusion

Late-onset, early cessation of rains and consequent shortened length of the growing season have impacted negatively production of maize in the forest-savannah agroecological zone of Nigeria. Adequate synchronization of crop production with the agricultural calendar of crops cannot be overemphasized especially at the face of climate change and variability. It is obvious from this study that plating dates have significant effects on the growth and yield of Maize. It is hereby recommended that for optimum yield of maize, planting should be done at the onset of rains in the forest savannah agroecological zone of Nigeria.

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