Effects of Urea and Ammonium Nitrate on Penetration of NAA Through Enzymatically Isolated Tomato Fruit Cuticular Membranes

2008 ◽  
pp. 15-15-17 ◽  
Author(s):  
MJ Bukovac ◽  
RG Fader ◽  
P Luque
Keyword(s):  
Ammonium Nitrate ◽  
Tomato Fruit

scholarly journals Enhancement of Transcuticular Penetration of NAA with Ammonium Nitrate and Triton × Surfactants as Spray Additives

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 525C-525 ◽  
Author(s):  
Royal G. Fader ◽  
Martin J. Bukovac
Keyword(s):  
Plant Growth ◽  
Ammonium Nitrate ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Tomato Fruit ◽  
Initial Slope ◽  
Plant Cuticle ◽  
Hygroscopic Properties ◽  
Pepper Fruit ◽  
Cuticle Thickness

The plant cuticle is the prime barrier to penetration of foliar-applied plant growth regulators (PGR). Spray additives of various chemistries are frequently included in a tank mix to increase performance of PGRs. We have reported that urea and ammonium nitrate (AN) enhance transcuticular penetration of 14C-labeled NAA (pKa 4.2) from aqueous droplets (pH 5.2) and their subsequent deposits through enzymatically isolated tomato fruit cuticular membranes (CM). Studies on effects of Triton × surfactants on AN-enhanced NAA penetration showed an additional 25% increase in NAA penetration and the AN:surfactant interaction was significant. Also, some alkylamine hydrochlorides increased NAA penetration. Studies comparing NAA penetration through tomato and pepper fruit and Citrus leaf CM in the presence of 8 mM AN or 8 mM ethylamine HCl showed that all three species exhibited the same trend for penetration at 120 h: ethylamine HCl > AN > NAA only. Comparative NAA penetration for CM of the three species was pepper > Citrus > tomato, with significant differences (P > 0.006) in NAA penetration, as indexed by initial slope and penetration after 120 h. On addition of AN, NAA penetration was greater (range 3% to 40%) for Citrus and pepper CM than tomato CM. When ethylamine HCl was added, NAA penetration through Citrus and pepper CM was less (–37 and –27%, respectively) than tomato CM as measured by the initial slope, but 6% and 11%, respectively, more than tomato CM for penetration after 120 h. The differences in NAA penetration among the three species cannot be explained by cuticle thickness, since pepper and tomato CM are 2.5- to 3.5-fold thicker than Citrus CM. We have suggested that the enhanced NAA penetration mediated by AN and ethylamine HCl (and other alkylamine HCl examined) may be related to their hygroscopic properties leading to greater deposit hydration. The significance of the differences among the species CM and surfactant-enhanced NAA penetration will be discussed, in relation to diffusion in the non-living, non-metabolic plant cuticle.

scholarly journals Further Studies on Enhancement of Transcuticular Penetration of NAA with Spray Additives

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 598a-598
Author(s):  
Royal G. Fader ◽  
Patricia Luque ◽  
Martin J. Bukovac
Keyword(s):  
Ammonium Nitrate ◽  
Initial Rate ◽  
Tomato Fruit ◽  
Nitrate Anion ◽  
Reaction Site ◽  
Cuticular Waxes ◽  
Methylamine Hydrochloride ◽  
Spray Droplets ◽  
Initial Penetration ◽  
Triton X

The cuticle is the prime barrier to penetration of foliar applied plant growth regulators, which must penetrate and be transported to a reaction site before a response can be induced. Urea has enhanced performance of Fe and Zn foliar sprays and a mixture of urea and ammonium nitrate (WAN) the performance of some herbicides. The mechanism of this enhancement is not clear. We find that urea and UAN increased 14C-NAA transport across enzymatically isolated tomato fruit cuticular membranes (CM) from simulated spray droplets using a finitedose diffusion system. The initial rate and total amount of NAA penetrated was significantly increased relative to NAA alone, the enhancement being greater for UAN than urea (total amount 101% vs. 78% at 120 hours) and for the NAA anion (pH 5.2, pKa 4.2) than for the nondissociated (pH 3.2) moiety. When evaluating the concentration effect of urea and NH4NO3 individually, the greatest enhancement with urea was at 62 mm and with NH4NO3 at 8 mm. Generally the effect of urea was significantly less than NH4NO3 (+24% vs. 296%). NAA penetration was greater with NH4NO3 than with KNO3 or Ca(NO3)2 or when the nitrate anion was replaced with sulfate or phosphate. Transcuticular penetration of NAA was enhanced greatly (190% in 120 hours) on removal of cuticular waxes; however, penetration was further increased (252% in 120 hours) by adding 8 mm NH4NO3. Methylamine hydrochloride (CH3NH2.HC1, 8 mm) also increased NAA diffusion, the initial slopes (>8 hours) were 23, 14, and 2 pmols·h–1 for methylamine, ammonium nitrate, and NAA alone, respectively, while the percent of applied that penetrated after 120 hours was 68.5, 67.6, and 21.4 for methylamine, ammonium nitrate, and NAA alone, respectively. The enhancement of NAA penetration by NH4NO3 equaled or exceeded that obtained with a group of surfactants of diverse chemistries. When the surfactant Triton X-100 was compared with NH4NO3, initial penetration was more rapid with ammonium nitrate (11.7 vs. 7.3 pmols·h–1) but percent penetrating after 120 hours was greater for Triton X-100 (80.5 vs. 66.8). The possible action of NH4NO3 on NAA uptake will be discussed.

Function of the polygalacturonase convertor in ripening tomato fruit

1991 ◽  
Vol 82 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Erik Knegt ◽  
Evert Vermeer ◽  
Caroline Pak ◽  
Johan Bruinsma
Keyword(s):  
Tomato Fruit
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