Effect of irrigation on soil oxygen status and root and shoot growth of wheat in a clay soil

Abstract

Two watering treatments (flood and control) were applied to undisturbed (bulk density �? 1.6 mg mm-3 ) and repacked �? 1.2 mg mm-3 ) cylinders of Marah clay loam. The cylinders (0.75 m o.d. by 1.4 m deep) were housed in a lysimeter facility. Wheat (cv. Egret) was grown in the cylinders and the soil was either kept well watered with frequent small amounts of water (control treatment) or subjected to three separate periods, ranging from 4 to 72 h, of surface inundation (flood treatment). The greater pore space and better drainage of the repacked soil ensured that its average level of soil oxygen (O2) was about three times that of the undisturbed soil. Nevertheless, inundation of the soil surface for either 48 or 72 h rapidly decreased soil O2 levels in both soils. Root growth in these soils appeared to be slowed when soil O2 levels became less than 15% of the maximum that would occur in dry, aerated soil. Root growth ceased in both repacked and undisturbed soil cores after a 48-h flooding, when the soil O2 status was probably < 10% of the maximum. Root growth was greatest in the repacked soil with controlled water additions. The ranking of treatments, by either root intercept counts or O2 status, were the same. Leaf and stem growth were not very sensitive to the root zone conditions, but this may have been due to the advanced stage of plant growth when the treatments were applied and to the generally low nitrogen status of all treatment plants. There was a 44% reduction in yield from the best to the worst aerated soil treatment. The data show that if soil O2 levels become low as the result of flooding, root growth of wheat will stop and grain yield will be substantially decreased. Greatly improved aeration of these fine-textured soils is only possible if both the internal drainage properties of the soil are improved and prolonged periods of surface inundation are avoided.

Effects of short-term flooding on growth, yield and mineral composition of wheat on sodic soil under field conditions

“…However, in our experiment no such recovery occurred. Meyer et al, (1985) also reported that flooding clay soils appeared to have no negative effect on vegetative top growth. In the present experiment flooding significantly reduced shoot dry weight (Table 2) and could be held responsible for reduced height and tillering (Tables 2 and 3).…”

“…It is well established that for most agricultural crops, not adapted to wetland conditions, flooding reduces shoot and root growth, dry matter accumulation and final crop yield (Belford, 1981, Cannell et al, 1980Gales et al, 1984). This damage has been mainly attributed to reduction in oxygen supply, reduced root growth, ionic imbalance and/or nutrient stress (Cannell et al, 1985;Leyshon and Sheard, 1974;Meyer et al, 1985). However, such information is entirely lacking in highly dispersed sodic soils in spite of the severe problem of water stagnation after irrigation or rains.…”

Differences in Vegetative Growth Response to Soil Flooding between Common and Tartary Buckwheat

“…Before research at the cellular level, the function of roots should be investigated since fl ooding changes the root environment directly and reduces shoot and root growth and fi nal grain yield for several crops (Lal and Taylor, 1969;Trought and Drew, 1980;Cannell et al, 1985;Setter and Waters, 2003). This reduction is mainly caused by a reduction in oxygen supply, reduced root growth, ionic imbalance and nutrient stress (Grable, 1966;Lal and Taylor, 1970;Meyer et al, 1985). It is well established that fl ooding imposes water stress in the shoot since water absorption is decreased in a smaller root system and/or physiologically injured roots (Chang et al, 1945;McDermott, 1945;Kramer, 1951).…”

Models for estimating capillary rise in a heavy clay soil with a saline shallow water table

“…An undisturbed soil core, 0.75 m diameter and 1.4 m deep, of Mundiwa clay loam was installed in the lysimeter at CSIRO Division of Water Resources, Griffith (Meyer et al 1985). Mundiwa clay loam is a duplex soil with approximately 0.2 m of clay loam overlying a heavy clay subsoil.…”