Effect of Post-Infiltration Soil Aeration at Different Growth Stages on Growth and Fruit Quality of Drip-Irrigated Potted Tomato Plants (<i>Solanum lycopersicum</i>)

<div><p>Soil hydraulic principles suggest that post-infiltration hypoxic conditions would be induced in the plant root-zone for drip-irrigated tomato production in small pots filled with natural soil. No previous study specifically examined the response of tomato plants (<i>Solanum lycopersicum</i>) at different growth stages to low soil aeration under these conditions. A 2 × 6 factorial experiment was conducted to quantify effects of no post-infiltration soil aeration versus aeration during 5 different periods (namely 27–33, 34–57, 58–85, 86–99, and 27–99 days after sowing), on growth and fruit quality of potted single tomato plants that were sub-surface trickle-irrigated every 2 days at 2 levels. Soil was aerated by injecting 2.5 liters of air into each pot through the drip tubing immediately after irrigation. Results showed that post-infiltration aeration, especially during the fruit setting (34–57 DAS) and enlargement (58–85 DAS) growth stages, can positively influence the yield, root dry weight and activity, and the nutritional (soluble solids and vitamin C content), taste (titratable acidity), and market quality (shape and firmness) of the tomato fruits. Interactions between irrigation level and post-infiltration aeration on some of these fruit quality parameters indicated a need for further study on the dynamic interplay of air and water in the root zone of the plants under the conditions of this experiment.</p></div

Irrigation × post-infiltration aeration interaction on titratable acidity and vitamin C content (fresh weight basis) of the first ripe fruit from the first truss of potted single tomato plants (n = 3).

<p><i>Notes</i>: Aeration treatment means at each irrigation level (n = 3) not followed by the same letter are significantly different at the 5% level. The t-test was used to compare 2 irrigation treatment means (n = 3) for each aeration treatment period and across aeration treatments (n = 18). The asterisk indicates significantly different irrigation means (* for p ≤ 0.05), (** for p ≤ 0.01, otherwise not significant (ns).</p><p>Aeration treatments were none or 2.5 liter aeration applied during 5 different periods. Pots were subsurface drip-irrigated at 2-day intervals to maintain the soil at 60 to 70% or 70 to 80% of volumetric field capacity (denoted as low and high irrigation level).</p

Axial and lateral diameter, and hardness measured on the first 8 ripe fruits harvested from the first trusses of 3 potted single tomato plants for 6 post-infiltration aeration treatments (i.e. none or 2.5 liter aeration applied during 5 different periods).

<p><i>Notes</i>: Irrigation and interaction effects were not significant (p>0.05) in ANOVA. Aeration treatment means across irrigation levels (n = 16) not followed by the same letter are significantly different at the 5% level.</p><p>Pots were subsurface drip-irrigated at 2-day intervals to maintain the soil at 60 to 70% or 70 to 80% of volumetric field capacity (denoted as low and high irrigation level).</p

Fruit yield, above-ground plant dry weight (g per plant), plant height (cm) and soluble solids content of the first ripe fruit from the first truss of potted single tomato plants for 6 post-infiltration aeration treatments (i.e. none or 2.5 liter aeration applied during 5 different periods) at 99 DAS.

<p><i>Notes</i>: Irrigation and interaction effects were not significant (p>0.05) in ANOVA. Aeration treatment means across irrigation levels (n = 6) not followed by the same letter are significantly different at the 5% level.</p><p>Pots were subsurface drip-irrigated at 2-day intervals to maintain the soil at 60 to 70% or 70 to 80% of volumetric field capacity (denoted as low and high irrigation level).</p

Root dry weight (g per plant) of potted single tomato plants (n = 3) measured at 57, 85, and 99 days after sowing (DAS) for the 6 post-infiltration aeration treatments (i.e. none or 2.5 liter aeration applied during 5 different periods) at the low and high irrigation levels (i.e. subsurface drip-irrigation to maintain soil at 60 to 70% and 70 to 80% of volumetric field capacity).

<p><i>Notes</i>: Irrigation and interaction effects were not significant (p>0.05) in ANOVA. Aeration treatment means at each irrigation level not followed by the same letter are significantly different at the 5% level</p><p>Root dry weight (g per plant) of potted single tomato plants (n = 3) measured at 57, 85, and 99 days after sowing (DAS) for the 6 post-infiltration aeration treatments (i.e. none or 2.5 liter aeration applied during 5 different periods) at the low and high irrigation levels (i.e. subsurface drip-irrigation to maintain soil at 60 to 70% and 70 to 80% of volumetric field capacity).</p