These symptoms aren't all quite the same.  Can you tell me more about fertility, how old the plants are and when they were transplanted out, how often they are irrigated, and have you looked at the roots of any of the affected plants?  Sometimes root issues show symptoms like these.  Have any herbicides been applied?  Are the taproots constrained by a hardpan?  What is the pH of the soil?  Mangoes don't like alkaline or high-salt soils, and do not tolerate drought well.

Sorry for being late to respond to your answer and answering your questions about my Mango trees. I were testing the soil and waiting for the results to answer you. I apologize to you. The trees were not fertilized this year. They are 2 years old and were transplanted in a greenhouse in February. I put in the hole before transplanting the trees 0.5 Kg organic fertilizer of chicken and 1 Kg chemical fertilizer of ratio 12-11-18. They are irrigated every 8 days for 1-2 hours. Unfortunately, I didn't look at the roots of the affected trees and I think that the taproots are not constrained by a hardpan. Also, I didn't use any herbicide in my orchard. Concerning the results of my soil, it stated that the type of the soil is clay and its pH is about 7.45. Also it stated that the soil is non-saline but having a low amount of phosphorus, medium to low amount of potassium, and a high percentage of calcium carbonate (about 25%). These are the answers to your questions. So what are the problems and what to do? Also I have an important question. I was advised to add Calcinit fertilizer (including 15.5% N + 19% Ca) to all my orchard including Citrus and Avocado Trees to the soil by irrigation. Is that correct?! Thank you for your patience and help.

This looks like a root or nutritional issue, perhaps a fertilizer burn?  Does the soil stay wet or get dry between watering?  I still think you need to check the roots for discoloration caused by damage or burn, or consider whether you have enough micronutrients available to the young plants.  Newly planted mango trees should be watered at planting and every other day for the first week or so, and then 1 to 2 times a week for the first couple of months. During prolonged dry periods (e.g., 5 or more days of little to no rainfall) newly planted and young mango trees (first 3 years) should be watered once a week. Once the rainy season arrives, irrigation frequency may be reduced or stopped.As for the recommendation for additional fertilizer, it seems you already have high calcium in your soil, so I would recommend you discuss the results of your soil test with the person recommending the fertilizer to double-check that this is indeed what you need.  In Florida, young trees should receive fertilizer applications every month during the first year, beginning with ¼ lb (114 g) and gradually increasing to one pound (455 g). Thereafter, 3 to 4 applications per year in amounts proportionate to the increasing size of the tree are sufficient (Table 3).