the applied concentration of aba can vary widely depending on the water volume applied to plants as well as other factors such as the plant age and size , and plant sensitivity to aba , but is generally in the range of about 1 ppm to about 10 , 000 ppm , preferably from about 10 to about 1000 ppm . it is also contemplated that salts of aba may be utilized in accordance with the present invention . as used herein , the term “ salt ” refers to the water soluble salts of aba . representative such salts include inorganic salts such as the ammonium , lithium , sodium , calcium , potassium and magnesium salts and organic amine salts such as the triethanolamine , dimethylethanolamine and ethanolamine salts . other ingredients such as surfactants can be used in compositions useful in the present invention . the presently preferred surfactant for aba performance is brij 98 ( polyoxyethylene ( 20 ) oleyl ether ) available from uniqema ( castle , del .). other surfactants that are also useful in the present invention , including but not limited to other surfactants in the brij family ( polyoxyethylene fatty alcohol ether ) from uniqema ( castle , del . ); surfactants in the tween family ( polyoxyethylene sorbitan esters ) from uniqema ( castle , del . ); silwet family ( organosilicone ) from union carbide ( lisle , ill . ); triton family ( octylphenol ethoxylate ) from the dow chemical company ( midland , mich . ); tomadol family ( ethoxylated linear alcohol ) from tomah3 products , inc . ( milton , wis . ); myrj family ( polyoxyethylene ( poe ) fatty acid esters ) from uniqema ( castle , del . ); span family ( sorbitan ester ) from uniqema ( castle , del . ); trylox family ( ethoxylated sorbitol and ethoxylated sorbitol esters ) from cognis corporation ( cincinnati , ohio ). these surfactants , commercially available for agricultural use , are also useful in the present invention : latron b - 1956 ( 77 . 0 % modified phthalic / glycerol alkyl resin and 23 . 0 % butyl alcohol ) from rohm & amp ; haas ( philadelphia , pa . ); caspil ( blend of polyether - polymethylsiloxanecopolymer and nonionic surfactant ) from aquatrols ( paulsboro , n . j . ); agral 90 ( nonyl phenol ethoxylate ) from norac concept . inc . ( orleans , ontario , canada ); kinetic ( 99 . 00 % proprietary blend of polyalkyleneoxide modified polydimethylsiloxane and nonionic surfactants ) from setre chemical company ( memphis , tenn . ); and regulaid ( 90 . 6 % 2 - butoxyethanol , poloxalene , monopropylene glycol ) from kalo , inc . ( overland park , kans .). many different commercial ornamental crops were obtained from local retailers , or from wholesale nurseries , and transported to a greenhouse for testing . plants were watered to saturation and allowed to stand and drain for about one hour . plants were selected for uniformity based on leaf area and arranged in a randomized complete block design , or a completely randomized design , on the greenhouse bench . the plants were sprayed or drenched with water or treatment solution equaling about 5 - 10 % of the pot volume . the plants were held without irrigation until all the plants wilted to a point when they were determined to be unmarketable . the plants were rated daily for the extent of wilting on a scale from 1 for no wilting to 4 for complete wilting . a rating of 2 . 5 was the point at which a plant was determined to be unmarketable and the previous day was recorded as the marketable life of that plant in days . the plants were rated for the extent of lower leaf yellowing or leaf or flower abscission on a scale from 1 for no yellowing or abscission to 4 for complete yellowing or abscission . a rating of 2 . 5 was the point at which a plant was determined to be unmarketable . the present invention may be illustrated by the following representative example . ornamental bedding plants were treated ( sprayed or drenched ) with water or 250 ppm abscisic acid ( s - aba ; aba ; s -(+)- abscisic acid ; +- aba , (+)-( s )- cis , trans - abscisic acid , (+)-( s )- cis , trans - aba ; s - aba ; ( s )- 5 -( 1 - hydroxy - 2 , 6 , 6 ,- trimethyl - 4 - oxo - 2 - cyclohexen - 1 - yl )- 3 - methyl -( 2z , 4e )- pentadienoic acid ; cas no . 21293 - 29 - 8 ) and then irrigation was withheld until all the plants wilted . plants were individually rated on a daily basis for degree of wilting and other undesirable characteristics like leaf yellowing . in table 1 , plants were drenched with water or a 250 ppm aba solution , and held in a greenhouse without irrigation . 1 classification : favorable = increased market life due to delayed wilting without the occurrence of unmarketable lower leaf yellowing or abscission , unfavorable = presence of unmarketable lower leaf yellowing or abscission . 2 market life extension = days of additional market life compared to control plants due to delayed wilting . 3 lower leaf yellowing = average rating where 1 = no yellowing , 2 . 5 = unmarketable due to lower leaf yellowing , and 4 = severe lower leaf yellowing . 4 leaf or flower abscission = average rating where 1 = no leaf or flower abscission , 2 . 5 = unmarketable due to leaf or flower abscission , and 4 = severe leaf or flower abscission . many bedding plants like new guinea impatiens are very favorable candidates for aba application because treated plants have much greater drought tolerance without any noticeable undesirable side effects . other plants like pansy are not favorable candidates for aba application because even though the treated plants are more drought tolerant the undesirable effect of aba - induced leaf yellowing often occurs . other plants like vinca are not favorable candidates for aba application because even though the treated plants are more drought tolerant the undesirable effect of flower abscission often occurs . still other plants like calibrachoa are not favorable candidates because undesirable side effects like severe leaf yellowing occur before wilting symptoms develop in the control and treated plants .