This is a usual question , very frequently asked. C4 plants have photosynthesis taking place in both mesophyll and bundle sheaths, adpated to tropical , semitropical and arid regions with temperature ranging from 35-45 0C , no photorespiration , with much less in crude proteins , all these meirts put C4 plants edging over C3 plants. This is the reason C4 rice is the flagship program of IRRI. Vegetable slike chinese spinach ctaegorised as C4 plants could hold promise.

C4 plants are more efficient than C3 due to their high rate of photosynthesis and reduced rate of photorespiration. The main enzyme of carbon fixation (Calvin cycle) is RuBisCO. When carbon dioxide concentration is low, RuBisCO takes up oxygen to perform photorespiration. In C4 plants, photorespiration is highly reduced because carbon dioxide concentration is high at the RuBisCO site. Also, these plants possess special leaf anatomy called ‘Kranz anatomy’ and undergo the C4 pathway of photosynthesis.

https://byjus.com/neet-questions/why-c4-plants-are-more-efficient-than-c3/

The ‘hidden treasures’ in the forests in the form of edible plants could easily play a positive and huge role in delivering a balanced and healthy diet, especially in poor parts of the world. Kindly check the following RG link:

Article The role of wild fruits and vegetables in delivering a balan...

Also, check:

Article The Roles and Values of Wild Foods in Agricultural Systems

Dear @Shujaat Ali

The C4 plants avoid big losses of ATP by avoiding (or at least largely reducing the rate of) photorespiration. C4 plants are more productive at higher temperatures. At higher temperatures, plants tend to close stomata to avoid losing water, which reduces CO2 availability, and traps O2 which increases photorespiration. C4 plants increase carbon acquisitioning by adding the C4 pathway to the C3 pathway. And, by increasing the concentration of CO2 captured in this way, C4 plants reduce the impact the photorespiration cycle has on productivity. However, C3 plants are more efficient at low temperatures because there is less need to close stomata, and are without the added expense of the C4 pathway. Therefore, C4 plants do not enjoy unconditional advantage over C3 plants. In nature, C3 plants are more abundant than C4 ones as they are more competitive.

To my opinion, your statement "In future scarcity of water will be big problem for C3 plant" appears to be misleading. Water scarcity is really a problem at high temperature to which C4 plants are adapted. And, if it is at all a problem, then what about sugarcane, a C4 plant which has a very low water productivity??

Dears, thank you for yours valuable suggestions.

I agree with Manal Hadi Kanaan, completely.