Using information and communication technologies to disseminate and exchange agriculture-related climate information in the Indo-Gangetic Plains

This report documents and analyses emerging trends in the delivery and exchange of climate information in institutionalized agricultural extension systems, as well as through information and communication technologies for development (ICT4D) efforts that have a rural–agricultural focus. Such an analysis aims to give a clearer indication of how to best direct potential future investments in sharing climate change information with noninstitutional stakeholders. The analysis covers four countries across the Indo-Gangetic Plains (IGP): Bangladesh, India (Punjab, Haryana, Uttarakhand, Uttar Pradesh, Bihar and West Bengal States), Nepal (Terai Region), and Pakistan (Punjab Province). The critical potential impacts of climate change across the IGP include drought, flooding, glacial lake outburst floods, and variability of river runoff and coastal salinity

Methodological approach for predicting and mapping the phenological adaptation of tropical maize (Zea mays L.) using multi‑environment trials

Open Access Journal; Published online: 7 Dec 2018Background The phenological development of the maize crop from emergence through flowering to maturity, usually expressed as a rate (i.e. 1/duration), is largely controlled by temperature in the tropics. Maize plant phenological responses vary between varieties and quantifying these responses can help in predicting the timing and duration of critical periods for crop growth that affect the quality and quantity of seed. We used routine multi-environment trials data of diverse tropical maize varieties to: (1) fit 82 temperature dependent phenology models and select the best model for an individual variety, (2) develop a spatial framework that uses the phenology model to predict at landscape level the length of the vegetative and reproductive phases of diverse varieties of maize in different agro-ecologies. Multi-environment trial data of 22 maize varieties from 16 trials in Kenya, Ethiopia, and Sudan was analyzed and the Levenberg–Marquardt algorithm combined with statistical criteria was applied to determine the best temperature-dependent model. Results The Briere model, which is not often used in plant phenology, provided the best fit, with observed and predicted days to flowering showing good agreement. Linking the model with temperature and scaling out through mapping gave the duration from emergence to maturity of different maize varieties in areas where maize could potentially be grown. Conclusion The methodology and framework used in the study provides an opportunity to develop tools that enhance farmers’ ability to predict stages of maize development for efficient crop management decisions and assessment of climate change impacts. This methodology could contribute to increase maize production if used to identify varieties with desired maturity for a specific agro-ecology in in the targeted regions

Options for calibrating ceres-maize genotype specific parameters under data-scarce environments

Open Access JournalMost crop simulation models require the use of Genotype Specific Parameters (GSPs) which provide the Genotype component of G×E×M interactions. Estimation of GSPs is the most difficult aspect of most modelling exercises because it requires expensive and time-consuming field experiments. GSPs could also be estimated using multi-year and multi locational data from breeder evaluation experiments. This research was set up with the following objectives: i) to determine GSPs of 10 newly released maize varieties for the Nigerian Savannas using data from both calibration experiments and by using existing data from breeder varietal evaluation trials; ii) to compare the accuracy of the GSPs generated using experimental and breeder data; and iii) to evaluate CERES-Maize model to simulate grain and tissue nitrogen contents. For experimental evaluation, 8 different experiments were conducted during the rainy and dry seasons of 2016 across the Nigerian Savanna. Breeder evaluation data were also collected for 2 years and 7 locations. The calibrated GSPs were evaluated using data from a 4-year experiment conducted under varying nitrogen rates (0, 60 and 120kg N ha-1). For the model calibration using experimental data, calculated model efficiency (EF) values ranged between 0.88–0.94 and coefficient of determination (d-index) between 0.93–0.98. Calibration of time-series data produced nRMSE below 7% while all prediction deviations were below 10% of the mean. For breeder experiments, EF (0.58–0.88) and d-index (0.56–0.86) ranges were lower. Prediction deviations were below 17% of the means for all measured variables. Model evaluation using both experimental and breeder trials resulted in good agreement (low RMSE, high EF and d-index values) between observed and simulated grain yields, and tissue and grain nitrogen contents. It is concluded that higher calibration accuracy of CERES-Maize model is achieved from detailed experiments. If unavailable, data from breeder experimental trials collected from many locations and planting dates can be used with lower but acceptable accuracy

Temperature variability and the yield of annual crops.

Abstract Global production of annual crops will be affected by the increases in mean temperatures of 2-4 • C expected towards the end of the 21st century. Within temperate regions, current cultivars of determinate annual crops will mature earlier, and hence yields will decline in response to warmer temperatures. Nevertheless, this negative effect of warmer temperatures should be countered by the increased rate of crop growth at elevated atmospheric CO 2 concentrations, at least when there is sufficient water. Of more importance for the yield of annual seed crops may be changes in the frequency of hot (or cold) temperatures which are associated with warmer mean climates. The objectives of this paper are to review evidence for the importance of variability in temperature for annual crop yields, and to consider how the impacts of these events may be predicted. Evidence is presented for the importance of variability in temperature, independent of any substantial changes in mean seasonal temperature, for the yield of annual crops. Seed yields are particularly sensitive to brief episodes of hot temperatures if these coincide with critical stages of crop development. Hot temperatures at the time of flowering can reduce the potential number of seeds or grains that subsequently contribute to the crop yield. Three research needs are identified in order to provide a framework for predicting the impact of episodes of hot temperatures on the yields of annual crops: reliable seasonal weather forecasts, robust predictions of crop development, and crop simulation models which are able to quantify the effects of brief episodes of hot temperatures on seed yield

Optimizing sowing density-based management decisions with different nitrogen rates on smallholder maize farms in northern Nigeria

Open Access Article; Published online: 18 Jan 2021In this study, the CERES-Maize model was calibrated and evaluated using data from 60 farmers’ fields across Sudan (SS) and Northern Guinea (NGS) Savannas of Nigeria in 2016 and 2017 rainy seasons. The trials consisted of 10 maize varieties sown at three different sowing densities (2.6, 5.3, and 6.6 plants m−2) across farmers’ field with contrasting agronomic and nutrient management histories. Model predictions in both years and locations were close to observed data for both calibration and evaluation exercises as evidenced by low normalized root mean square error (RMSE) (≤15%), high modified d-index (> 0.6), and high model efficiency (>0.45) values for the phenology, growth, and yield data across all varieties and agro-ecologies. In both years and locations and for both calibration and evaluation exercises, very good agreements were found between observed and model-simulated grain yields, number of days to physiological maturity, above-ground biomass, and harvest index. Two separate scenario analyses were conducted using the long-term (26 years) weather records for Bunkure (representing the SS) and Zaria (representing the NGS). The early and extra-early varieties were used in the SS while the intermediate and late varieties were used in the NGS. The result of the scenario analyses showed that early and extra-early varieties grown in the SS responds to increased sowing density up to 8.8 plants m−2 when the recommended rate of N fertilizers (90 kg N ha−1) was applied. In the NGS, yield responses were observed up to a density of 6.6 plants m−2 with the application of 120 kg N ha−1 for the intermediate and late varieties. The highest mean monetary returns to land (US$1336.1 ha−1) were simulated for scenarios with 8.8 plants m−2 and 90 kg N ha−1, while the highest return to labor (US$957.7 ha−1) was simulated for scenarios with 6.6 plants m−2 and 90 Kg N ha−1 in the SS. In the NGS, monetary return per hectare was highest with a planting density of 6.6 plants m−2 with the application of 120 kg N, while the return to labor was highest for sowing density of 5.3 plants m−2 at the same N fertilizer application rates. The results of the long-term simulations predicted increases in yield and economic returns to land and labor by increasing sowing densities in the maize belts of Nigeria without applying N fertilizers above the recommended rates

Effect of drought and plant density on radiation interception, radiation use efficiency and patitioning of dry matter to seeds in cowpea

The effects of drought and plant density on fractional interception (f), radiation-use efficiency (RUE) and dry matter accumulation and partitioning to seeds in cowpea (Vigna unguiculata) need to be quantified in order to calibrate cowpea simulation models for West Africa. Accordingly, a short duration cultivar of cowpea, IT84S-2246-4, was grown at a range of plant densities in well-watered and drought conditions in 1990–91 at two contrasting locations in Nigeria, Ibadan (7°N) and Kano (12°N). Fractional interception of radiation (f) and total above-ground dry matter accumulation (TDM) were measured throughout the growing season and TDM and seed yield (SY) were measured at maturity. At Ibadan drought had no effect on phenology while at Kano drought increased the duration of the vegetative phase (by 5–6 days), but not of the reproductive phase. Drought reduced f and radiation-use efficiency (RUE), and hence TDM, and there were significant interactions between RUE and plant density at both Kano and Ibadan. Average SY in the well-watered treatments at Kano and Ibadan were 1600 and 700 kg ha⊃−1&/sup; respectively and drought reduced SY by 50% at both sites but did not interact with plant density. Across locations, plant densities and drought treatments SY was strongly correlated (r = 0.96) with TDM production between flowering and maturity. These data suggest that partitioning of dry matter during the reproductive phase is not affected by location, drought or plant density and the SY of cowpea can be predicted from dry matter accumulation

Leaf appearance in cowpea: effects of temperature and photoperiod

Leaf appearance in crop plants is an important process involved in canopy development. The environmental control of leaf appearance has not been studied in cowpea [Vigna unguiculata (L.) Walp.]. This study was conducted to determine whether photoperiod has any effect on the rate of leaf appearance (RLA) and to determine the phyllochron and its base temperature in cowpea. Five genotypes from W. Africa were sown on nine occasions between 1990 and 1992 at Kano, Nigeria, (12°03′N). Plants were grown in pots under short (9.7–10.8 h d−1), natural (12.3–13.5 h d−1), and long (13.5–14.4 h d−1) day lengths and at mean daily temperatures of between 20.9 and 29.8°C. Eight genotypes, including the five genotypes grown in Nigeria, were also grown at seven mean temperatures ranging from 15.4 to 33.7°C in controlled environment glasshouses during 1994 in the UK. Leaf number on the main shoot was recorded every 2 to 3 d during the course of the experiments. No significant effects (P > 0.05) of photoperiod on RLA were detected in any genotype. Temperature significantly (P < 0.001) affected RLA in all genotypes. The relationship between RLA and mean temperature was similar in experiments in Nigeria and controlled environments. A comparison of the combined Nigerianand controlled environment data sets revealed significant (P < 0.01) differences between genotypes in the intercept but not in the slope of the relationship between RLA and mean temperature. The phyliochron, expressed as thermal time (0) per leaf, was therefore the same in all genotypes, 42°C d, above a base temperature that varied from 7 to 12°C. These values of the phyllochron and its base temperature are similar to those reported for other tropical legumes

Impacts of climate change on rainfed agriculture and adaptation strategies to improve livelihoods

This book provides a comprehensive presentation of the realization of improved rainfed agriculture yield in semi-arid and dry land areas. The incentive of watershed programs is to increase the return on investment with over 20% for 65% of the projects that are currently underperforming. Besides techniques to improve the livelihood of the many small-scale farmers in developing countries, it includes examples and case studies for further support. The methods discussed have recently shown to be successful and economically remunerative in India and in various African countries