Climate change is among the most crucial concerns of the world. It is a serious threat to the global agriculture and its overall impact on global agriculture is yet not clear. A rise of 2.5-4.5◦C is expected in the global temperature until the end of 21st century. The amount of greenhouse gases particularly CO2 is increasing at an alarming rate and is enhancing the plant photosynthesis and productivity. However, this increase in productivity is counteract by the more negative effects of climate change on agriculture like increased evapotranspiration, drought, floods, changes in the amount and distribution of rainfall, higher pest infestations and more irrigation demand. Climate change also affects the nutrients availability and efficiency by influencing microbial activities and population in the soil. Therefore, adaptation of agriculture sector to the changing climate is indispensable because of its sensitivity and size. This review is aimed to document the possible impacts of climate change on agriculture, its causes and future projections. Some strategies are also advised to mitigate the emission of greenhouse gases, to reduce the negative impacts of climate change on agriculture and to make new policies keeping in view their broader consequences on agriculture.

Manganese deficiency critically impairs the function and stability of photosystem II (PSII) and negatively impacts crop growth and yield. However, the response mechanisms of carbon and nitrogen metabolism to Mn deficiency in different genotypes of maize and the differences in Mn deficiency tolerance are unclear. Herein, three different genotypes of maize seedlings (sensitive genotype: Mo17, tolerant genotype: B73, and B73 × Mo17) were exposed to Mn deficiency treatment for 16 days using liquid culture with different concentrations of MnSO₄ [0.00, 2.23, 11.65, and 22.30 mg/L (control)]. We found that complete Mn deficiency significantly reduced maize seedling biomass; negatively affected the photosynthetic and chlorophyll fluorescence parameters; and depressed nitrate reductase, glutamine synthetase, and glutamate synthase activity. This resulted in reduced leaf and root nitrogen uptake, with Mo17 being most severely inhibited. B73 and B73 × Mo17 maintained higher sucrose phosphate synthase and sucrose synthase activities and lower neutral convertase activity compared to Mo17, which resulted in higher accumulation of soluble sugars and sucrose and maintenance of the osmoregulation capacity of leaves, which helped mitigate damage caused by Mn deficiency. The findings revealed the physiological regulation mechanism of carbon and nitrogen metabolism in different genotypes of maize seedlings that resist Mn deficiency stress, providing a theoretical basis for developing high yield and quality.