Aim of study: Radiation parameters and photoperiod influence potato biomass and tuber yield significantly. Lack of instrument facilities in developing countries is the main hindrance to estimate global solar radiation (GSR) and radiation use efficiency (RUE). Considering these facts, an experiment was conducted to estimate light extinction coefficient (K) and RUE using a simple but indirect approach that can be implied in any location lacking sophisticated instruments.Area of study: Field experiments were conducted in Kalyani, West Bengal, representing the Indo-Gangetic Plains.Material and methods: Angstrom-Prescott (A-P) equation was used to calculate GSR. The experiment was laid out in a split-plot design with three dates of planting (DOP), 15th Nov, 29th Nov and 13th Dec, as main plot treatment and three potato cultivars (ˈKufri Suryaˈ, ˈKufri Chandramukhiˈ and ˈKufri Jyotiˈ) as sub-plot treatment. Leaf area indices and K values were used to determine intercepted PAR (IPAR) as well as RUE.Main results: The cumulative IPAR from emergence to harvest ranged 246-429 MJ m-2 depending on planting time and varieties. Irrespective of DOPs, the highest mean RUE (4.19 g MJ-1) was calculated in ˈKufri Chandramukhiˈ, showing that it used the radiation more efficiently that the other two cultivars (ˈKufri Suryaˈ= 3.75 g MJ-1 and ˈKufri Jyotiˈ= 3.14 g MJ-1).Research highlights: Statistical indices confirmed that the A-P model can be reliably used in the study region for estimation of GSR. This simple way to estimating RUE using bright sunshine hours data can be used in developing countries, where costly radiation instruments are not available.

No abstract

No abstract

Solar radiation is the key energy source for most of the energy conversion systems, whether it is biological or mechanical. It is also the most fundamental energy source for future energy demand. Like most of the developing countries, India also lacks sufficient instrument facilities to measure global solar radiation (GSR) at recommended spatial interval and alternative approaches must be used to generate GSR data. In the present study, six well known empirical models were tested to estimate the GSR over twelve major cities of India using long-term global solar radiation and bright sunshine hour data. The empirical coefficients have been calculated for all the models and each location using regression analysis method. Daily GSR are then calculated using those regression constants along with statistical analysis. Results reveal that all the models shows close estimation with low mean bias error (MBE), root mean square error (RMSE) and mean percentage error (MPE) values. Among all models, linear exponential and linear logarithmic models are highly recommended for prediction of GSR throughout the country, except Shillong, where Bakircilinear exponential model is recommended. Significance tests i.e., t-test also confirms that this two model produce most significant results than others.

An experiment was conducted in the experimental farm of Bidhan Chandra KrishiViswavidyalaya, Nadia, West Bengal to study the radiation pattern and its balance over green gram (Vignaradiata var. Samrat). The BREB method was used to determine the sensible heat flux and latent energy. The net radiation was measured through net radiometer and the ground heat flux was measured using Fourier's law. Both the diurnal and seasonal variation of net radiation were studied. Similarly, the energy balance components were studied regularly for different crop growth stages as well as on diurnal basis. It is observed that the net radiation varies from 6.32 Wm-2 to 606.43 Wm-2. The latent heat flux constitutes more than 50% of the net radiation for all growth stages as depicted by energy balance partitioning. The sensible heat flux is partitioned into 10% to 20% of total net radiation throughout the growth stages of green gram, which is the lowest in magnitude among all three energy fluxes. The relationship between Bowen ratio and Vapour pressure deficit (VPD), Bowen ratio and Canopy air temperature difference (CATD) was studied. It was found that Bowen ratio is negatively correlated with VPD but positively correlated with CATD. This study enables to monitor ET pattern through latent heat flux and microclimatic characteristics through sensible and ground heat flux.