Hi Suresh,

Please check the links given below.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405239/

https://isaaa.org/resources/publications/pocketk/32/default.asp

Best of Luck

It depends on which resources you have. If you have an known and well-characterized drought-related gene, you can transform it to develop a drought-tolerant elite line. For example, Monsanto has developed a drought-tolerant corn (DroughGard® corn) with a single gene cspB (see below link). On the other hand, if you have a drought-tolerant line (which the trait gene(s) are not well characterized), you can breed the drought-tolerant trait into an elite line by making crosses and marker-assisted backcrossing breeding programs.

DroughGard® corn: http://www.genuity.com/research/Pages/Genuity-DroughtGard-Hybrids.aspx?gclid=CjwKEAjwjca5BRCAyaPGi6_h8m8SJADryPLhKXNNMjc8oApiX2XqZ6lSngSdzF72E42qa4VKKNRVTBoCP_Hw_wcB

There are different droughts and their timing and degree require different strategies. The main issue is the avoidance of seed and labour dispersal and crop tailoring to water sustainable use. Soil permeability and organic structure play a fundamental role, but single traits can improve a specific tolerance

As explained by Guido Bongi nature of droughts are of various types, drought may be due to lack of moisture due to low moisture (low rain fall) with high temperature, drought may be due to cold and water become unavailable to plant due to freezing. 

Whatever is your target environment screen your available genotype or segregating material in target environment and take the observation on your screening genotype when stress is available and select for the genotype which showing maximum normal behavior or less affected by stress.

There are several  traits in various crops like deep root, waxy leaf, small size of leaf etc which imparts resistance to drought, selection for these traits also help in getting resistance. 

Biochemical contents in leaf like prolin etc are also help in drought tolerance.

Most easiest and effective way is selection in target environment (rather than selection for one ore two traits) in various segregating population and fixing gene by selecting high yielding with resistance and selfing and again screening plant to row progenies.

Drought is a complex constraint to which it would be difficult to define a standard approach. First, you need to know what type of drought (vegetative, reproductive, intermittent, etc.) is your goal.

Thus, you must screen the varieties (parental lines) in field/screen-house according to your goal. This implies a rigor on the effective water management to justify your type of drought.

Once you have identified a / the variety (ies) tolerant to drought, consider that you have a source of resistance (donor genes). If your source is potentially qualitative, you will directly exploit. If it is not good for other traits such as yield, susceptible to disease; it must be included in a breeding program to improve a susceptible elite variety.

Two choices are available:

1- Conventional breeding

2- Marker-Assisted Selection (Biotechnological approach) that is ‘’the best’’

In both cases, after F3 generation, you'll phenotype population in the field or in a greenhouse for several years to identify the best individuals at F9 or F10.

The most important is a good phenotyping result showing a polymorphism in your population.

This link might be useful

https://www.researchgate.net/publication/51921685_Agro-morphological_characterization_of_a_population_of_introgression_lines_derived_from_crosses_between_IR_64_Oryza_sativa_indica_and_TOG_5681_Oryza_glaberrima_for_drought_tolerance

Article Agro-morphological characterization of a population of intro...

Dear Roland 

I think first the determination of what type of drought is to be rsesited is to be identified.Then isolation of a paricular gene from a particular plant as a source which has alraedy resisted to that drought condition is t o be done..Then fuse it by gene cloning with the desired plant.Breed that plant in green house condition for salt tolerance or drought tolerance.I think this can be an approach. 

Of course, the case a gene was identified before the approach of Debojyoti Roychowdhury could be considered.

I would say: it depens. No best approach..Would you tell more about your plant?

Tq aravind sir for ur help

Thank you so much everyone. Your knowledge helps me to better understand about what iam searching for