TY - JOUR

T1 - Inhibition of tomato shoot growth by over-irrigation is linked to nitrogen deficiency and ethylene

AU - Fiebig, Antje

AU - Dodd, Ian C.

PY - 2016/1

Y1 - 2016/1

N2 - Although physiological effects of acute flooding have been well studied, chronic effects of suboptimal soil aeration caused by over-irrigation of containerized plants have not, despite its likely commercial significance. By automatically scheduling irrigation according to soil moisture thresholds, effects of over-irrigation on soil properties (oxygen concentration, temperature and moisture), leaf growth, gas exchange, phytohormone [abscisic acid (ABA) and ethylene] relations and nutrient status of tomato (Solanum lycopersicum Mill. cv. Ailsa Craig) were studied. Over-irrigation slowly increased soil moisture and decreased soil oxygen concentration by 4%. Soil temperature was approximately 1 degrees C lower in the over-irrigated substrate. Over-irrigating tomato plants for 2 weeks significantly reduced shoot height (by 25%) and fresh weight and total leaf area (by 60-70%) compared with well-drained plants. Over-irrigation did not alter stomatal conductance, leaf water potential or foliar ABA concentrations, suggesting that growth inhibition was not hydraulically regulated or dependent on stomatal closure or changes in ABA. However, over-irrigation significantly increased foliar ethylene emission. Ethylene seemed to inhibit growth, as the partially ethylene-insensitive genotype Never ripe (Nr) was much less sensitive to over-irrigation than the wild type. Over-irrigation induced significant foliar nitrogen deficiency and daily supplementation of small volumes of 10 mM Ca(NO3)(2) to over-irrigated soil restored foliar nitrogen concentrations, ethylene emission and shoot fresh weight of over-irrigated plants to control levels. Thus reduced nitrogen uptake plays an important role in inhibiting growth of over-irrigated plants, in part by stimulating foliar ethylene emission.

AB - Although physiological effects of acute flooding have been well studied, chronic effects of suboptimal soil aeration caused by over-irrigation of containerized plants have not, despite its likely commercial significance. By automatically scheduling irrigation according to soil moisture thresholds, effects of over-irrigation on soil properties (oxygen concentration, temperature and moisture), leaf growth, gas exchange, phytohormone [abscisic acid (ABA) and ethylene] relations and nutrient status of tomato (Solanum lycopersicum Mill. cv. Ailsa Craig) were studied. Over-irrigation slowly increased soil moisture and decreased soil oxygen concentration by 4%. Soil temperature was approximately 1 degrees C lower in the over-irrigated substrate. Over-irrigating tomato plants for 2 weeks significantly reduced shoot height (by 25%) and fresh weight and total leaf area (by 60-70%) compared with well-drained plants. Over-irrigation did not alter stomatal conductance, leaf water potential or foliar ABA concentrations, suggesting that growth inhibition was not hydraulically regulated or dependent on stomatal closure or changes in ABA. However, over-irrigation significantly increased foliar ethylene emission. Ethylene seemed to inhibit growth, as the partially ethylene-insensitive genotype Never ripe (Nr) was much less sensitive to over-irrigation than the wild type. Over-irrigation induced significant foliar nitrogen deficiency and daily supplementation of small volumes of 10 mM Ca(NO3)(2) to over-irrigated soil restored foliar nitrogen concentrations, ethylene emission and shoot fresh weight of over-irrigated plants to control levels. Thus reduced nitrogen uptake plays an important role in inhibiting growth of over-irrigated plants, in part by stimulating foliar ethylene emission.

KW - ZEA-MAYS-L

KW - ABSCISIC-ACID

KW - 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID

KW - OXYGEN DEFICIENCY

KW - WATER RELATIONS

KW - LEAF EXPANSION

KW - XYLEM SAP

KW - STOMATAL CONDUCTANCE

KW - AERENCHYMA FORMATION

KW - ANTI-TRANSPIRANT

U2 - 10.1111/ppl.12343

DO - 10.1111/ppl.12343

M3 - Journal article

VL - 156

SP - 70

EP - 83

JO - Physiologia Plantarum

JF - Physiologia Plantarum

SN - 0031-9317

IS - 1

ER -