Modeling growth and yield of groundnut
Crop simulation models have much potential for assisting in agrotechnology transfer, crop management decision-making, climatic assessment, and in the synthesis of research results. For these reasons, it is important to continue to develop and improve models for predicting the growth and yield of groundnut (Arachis hypogaea). In this paper, we briefly review approaches for modeling growth and yield of groundnut. Then we illustrate major areas of improvement in the PNUTGRO crop growth model after evaluating PNUTGRO Vi.02 versus additional data sets from Florida and India. New areas of improvement include: 1) addition of a hedgerow photosynthesis submodel to improve response to row spacing, sowing density, and growth habit; 2) addition of the Pen mall equation to incorporate vapor pressure deficit and windspeed to estimate evapotranspiration for arid regions; 3) modification oJfunctions for prediction of crop del’elopment; and 4) modification of the effects of stress environments such as high temperature and vapor pressure deficit on partitioning. 
Effect of mulch on soil temperature, moisture, weed infestation and yield of groundnut in northern Vietnam
Groundnut (Arachis hypogaea L.) is one of the chief foreign exchange earning crops for Vietnam. However, owing to lack of appropriate management practices, the production and the area under cultivation of groundnut have remained low. Mulches increase the soil temperature, retard the loss of soil moisture, and check the weed growth, which are the key factors contributing to the production of groundnut. On-farm trials were conducted in northern Vietnam to study the impact of mulch treatments and explore economically feasible and eco-friendly mulching options. The effect of three mulching materials (polythene, rice straw and chemical) on weed infestation, soil temperature, soil moisture and pod yield were studied. Polythene and straw mulch were effective in suppressing the weed infestation. Different mulching materials showed different effects on soil temperature. Polythene mulch increased the soil temperature by about 6 °C at 5 cm depth and by 4 °C at 10 cm depth. Mulches prevent soil water evaporation retaining soil moisture. Groundnut plants in polythene and straw mulched plots were generally tall, vigorous and reached early flowering. Use of straw as mulch provides an attractive and an environment friendly option in Vietnam, as it is one of the largest rice growing countries with the least use of rice straw. Besides, it recycles plant nutrients effectively. 
Effects of sowing date and growth duration on growth and yield of groundnut in a Mediterranean-type environment in Turkey
Matching the phenology of the crop to the duration of favorable conditions by selecting the most appropriate sowing dates to avoid periods of stress is crucial for maximum yield. A 2-year field study was conducted to assess the effects of climatic factors on groundnut growth and yield at various dates of sowing in a Mediterranean-type environment at Hatay, Turkey in 2001 and 2002. Two cultivars (NC 7 and Com) were sown at five sowing dates (15 April, 1 May, 15 May, 1 June and 15 June) to expose the groundnut plant to a variety of climatic conditions, and were harvested at 120, 140 or 160 days after emergence. Sowing dates, cultivars and growth durations significantly affected to pod yield, number of pod per plant, shelling percentage, 100-seed weight, biomass, harvest index, crop growth rate, and oil and protein content. Very early sowing before 1 May did not generate any advantage for earliness and yield due to sub-optimal temperature for vegetative growth. Our results revealed that the most suitable period for groundnut sowing is between mid-May and early June for the eastern Mediterranean region since plants expose to suitable temperature regimes during the vegetative and the reproductive growth stages, and receive more solar radiation and sunshine duration during the entire growing period. Lengthening of growth duration had positive effect on yield at early sowings, but satisfactory yield level can be achieved with 140 days growth duration using current cultivars. It is also possible to obtain over 3.0 t ha−1 pod yield, which is considered as acceptable level by the grower in the region with shorter growth duration in double crop production. It was concluded that Mediterranean climate offers a long and suitable environment having at least 160 calendar days or 2400–2500 °Cd thermal time for both main and double crop production of the groundnut with acceptable yield levels.
Temperature Use Efficiency and Yield of Groundnut Varieties in Response to Sowing Dates and Fertility Levels in Western Dry Zone of India
A field experiment was conducted in loamy sand soil during kharif season of 2009 and 2010 to evaluate the temperature use efficiency and yield of groundnut varieties in response sowing dates and fertility levels. The treatments consisted of four sowing dates (20 April, 15 May, 9 June and 4 July) and two varieties of groundnut (HNG 10 and TG 37A) as main-plot treatments and four fertility levels of nitrogen and phosphorus application (0, 20 N-40 P2O5, 30-60 P2O5 and 40 N-80 P2O5 kg ha-1 ) as sub-plot making a total of 32 treatment combinations. The experiment was laid out in split-plot design with three replications and crop growth rate, yield parameters, harvest index and temperature use efficiency were recorded on crop. The results showed that significantly higher crop growth rate (CGR) at 30-60 and 60-90 days after sowing (DAS) was observed in HNG 10 variety. Further delays in sowing from 9 June significantly reduce crop growth rate. However, the growth rate of TG 37A variety was observed to be statistically at par among the sowing dates. In HNG 10 variety higher pod yield (3773, 3743 and 3738 kg ha-1), kernel, haulm and biological yield were observed at par to each other from 20 April to 9 June sowing, respectively. Maximum heat unit efficiency (3.23 kg ha-1 degree- day-1) was observed on 9 June sowing date while the highest yield (2628 kg ha-1) was recorded in TG 37A variety with 4 July sowing. Harvest index in both the varieties was observed to be significantly higher in 4 July sowing date. All the fertility treatments produced significantly higher crop growth rate and yields than the treatments receiving no fertilizer application. Application of 30 kg N-60 kg P2O5 ha-1 significantly enhanced the crop growth and yield over 20 kg N-40 kg P2O5 ha-1 and control but at par with 40 kg N-80 kg P2O5 ha-1 . However, the crop uses maximum temperature in the month of June for better growth and yield. Thus, it could be concluded that the suitable sowing date of HNG 10 and TG 37A varieties in western dry zone of India are around 9 June and 4 July respectively. Application of 30 kg N-60 kg P2O5 ha-1 was optimum for growth and yield of the crop.
Optimization of Oil Yield from Groundnut Kernel (Arachis hypogeae) in an Hydraulic Press Using Response Surface Methodology
Aim: The present study investigated the effect of operating parameters on the mechanical extraction of oil from groundnut kernel using hydraulic press
Methodology: A five factor, five levels central composite design (CCD) was applied to determine the effects of five independent variables (moisture content, heating temperature, heating time, applied pressure and pressing time) on oil yield. Response surface analysis method was employed to optimize the parameters in the experiment.
Results: Data analysis shows that all the variables signiï¬cantly affected the oil yield at 95% confidence level. Optimum oil yield of 32.36 % was obtained when the moisture content, heating temperature, heating time, applied pressure and pressing time were 8.13%, 81.93ºC, 7.03 minutes, 15.77 Mpa and 6.69 minutes, respectively. The experimental values were very close to the predicted values and were not statistically different at p<0.05.
Conclusion: The regression model obtained has provided a basis for selecting optimum process parameters for the recovery of oil using mechanical press. 
 Boote, K.J., Jones, J.W. and Singh, P., 1992. Modeling growth and yield of groundnut.
 Ramakrishna, A., Tam, H.M., Wani, S.P. and Long, T.D., 2006. Effect of mulch on soil temperature, moisture, weed infestation and yield of groundnut in northern Vietnam. Field crops research, 95(2-3), pp.115-125.
 Caliskan, S., Caliskan, M.E., Arslan, M. and Arioglu, H., 2008. Effects of sowing date and growth duration on growth and yield of groundnut in a Mediterranean-type environment in Turkey. Field Crops Research, 105(1-2), pp.131-140.
 Meena, R.S., Yadav, R.S., Reager, M.L., De, N., Meena, V.S., Verma, J.P., Verma, S.K. and Kansotia, B.C., 2015. Temperature use efficiency and yield of groundnut varieties in response to sowing dates and fertility levels in Western Dry Zone of India. Journal of Experimental Agriculture International, pp.170-177.
 Olajide, J.O., Afolabi, T.J. and Adeniran, J.A., 2014. Optimization of oil yield from groundnut kernel (Arachis hypogeae) in an hydraulic press using response surface methodology. Journal of Scientific Research and Reports, pp.1916-1926.