Increase In Mean Minimum Temperature Research Articles

Trends of the observed temperature and its variations in the Tamil Nadu State of India

In this study, the trends of the annual and seasonal temperature and its variations are explored in the Tamil Nadu State of India. In order to find the trend direction and the magnitude of change across the state during 1969–2016, the mean maximum temperature (MMaxT), mean minimum temperature (MMinT), and mean annual temperature (MAT) of 17 climatological stations are analyzed. Evidently, the increasing trends in MMaxT, MMinT, and MAT are observed at the majority of the stations. Approximately 82% of the total stations have shown a significant positive trend in MAT and MMaxT at the 95% confidence level. The MAT has increased up to 1.4 °C with a variation in the rate of change from 0.01 to 0.29 °C per decade. MMaxT has shown a significant increase with a variation in the rate of change from 0.01 to 0.54 °C per decade for the last 47 years. However, MMinT has shown an increasing trend in 13 stations and a decreasing trend in 4 stations with a variation in the rate of change from − 0.05 to 0.31 °C per decade. In the recent decades, the majority of the stations have experienced high warm and the year 2016 is observed to be the warmest year. Based on a spatial scale, temperature differences have been observed between coastal and inland stations. The majority of the coastal stations have shown a high increase in MMaxT as compared to the inland and hill stations. On the contrary, the inland stations have shown a high increase in MMinT as compared to the coastal stations. A more definite increasing trend is observed during the winter and postmonsoon seasons followed by the monsoon season.

Adverse effect of increase in minimum temperature during early grain filling period on grain growth and quality in indica rice (Oryza sativa) cultivars

Increasing global temperatures have a deterimental effect on rice quality besides leading to yield penalty. Past data shows that minimum temperature has increased more than maximum temperature in India as well as other parts of the world. The effect of this increase in mean minimum temperature on grain growth and quality of indica rice (Oryza sativa L.) cultivars is obscure. Our study submits the evaluation of grain quality of early, mid-early and medium duration indica rice cultivars to moderate increase in mean minimum temperature from anthesis to maturity in two seasons (kharif 2014 and 2015) . Early duration susceptible cultivars, Vandana and Parijat were significantly affected during the early phase of grain filling resulting in 4.6 and 6.4% decline in test weight and 12-18% in high density grains respectively, when the mean minimum temperatures were ≥ 25°C. Slower grain growth rate under elevated mean minimum temperature accounted for decrease in dry matter accumulation in these cultivars. In general, percentage chalkiness was less in all the indica cultivars. Head rice recovery was not affected but amylose content reduced in all cultivars with a significant effect on Bakal and Sahbhagi Dhan when minimum temperatures increased by more than 23°C. Rice cooking temperature determined by alkali spreading value was not stable across the environment in early duration cultivars, Vandana and Parijat. Increase in mean minimum temperature elicited the vulnerability of early duration indica cultivars, by adversely affecting quality traits like test weight, high density grains and gelatinization temperature.

Climatic Variability and its Implications on Agricultural Productivity in Central Punjab

Enhanced greenhouse effect due to anthropogenic activities has resulted in climatic changes and their adverse impacts on agricultural productivity. Different regions of earth are experiencing climatic changes of varying magnitudes. To deal with the situation; there is a dire need of temporal analysis of climatic records to quantify the climatic changes and their likely impacts on agricultural productivity. In the present investigation, long term climatic records of central Punjab (Ludhiana) w.r.t. maximum temperature (Tmax), minimum temperature (Tmin), relative humidity (RH), wind speed (WS), sunshine hours (SSH) and open pan evaporation (PE) for a period of 47 years (1970 to 2016) were analysed on monthly, seasonal and annual basis. Analysis indicated significant annual increase in mean minimum temperature (@0.06°C), relative humidity (@1.3per cent) and decrease in wind speed (@0.67 km day−1), sunshine hours (@0.03 hr day−1) and open pan evaporation (@ 6.0 mm), whereas no significant trend has been observed in maximum temperature. Monthly variability in minimum temperature indicated the highest rate of increase (0.7°C per decade) during reproductive growth and maturity period of rabi (February and March) and Kharif (September and October) crops, which can have adverse effects on their productivity. Similarly increase in relative humidity and decrease in wind speed and sunshine hours can have serious implications on occurrence of insect-pests, rate of crop photosynthesis and yields indicating a dire need of exploring genetic and agronomic manipulations to counterbalance the adverse effects of climate change, minimize climatic risks and sustain agricultural productivity in the region.