The Response of the Young Tomato Plant to a Brief Period of Water Shortage

Abstract

SummaryThe growth response was determined of young tomato plants subjected to wilting treatments of short duration. The experiments were conducted in pots in the glasshouse using Jondaryan loam, and the wilting treatments were at a "moderate" and a "severe" level. Even with the severe treatment, soil water did not fall below the permanent wilting percentage.Both wilting treatments reduced growth during the period of wilting,· but growth rates upon re-watering were greater than for the control plants. There was no indication that this recovery effect was complete at the final harvest.During wilting, a higher stem weight ratio and a lower lamina weight ratio were developed than in the control, and r~lative growth rates and net assimilation rates were depressed in both treatments. After wilting, lamina weight ratios became higher than control, stem weight ratios became lower, and net assimilation rates and relative growth rates rose above control values.These treatment effects may be interpreted as a tendency towards senescence during wilting and a return to a more juvenile condition upon re-watering.It was concluded that the changes in weight ratios were due to modifications of the normal pattern of translocation between plant parts. It was also concluded that the changes occurring in response to the water shortage were initiated relatively early in the drying cycle.The effects of water shortage on the water economy of the plant were also considered. It was found that, whilst there was a high effiCiency of transpiration during wilting, the drastic effects of the water shortage on growth made the greater efficiency of doubtful merit. After wilting, there was no economy in water usage by plants of either of the wilt treatments.

The Physiology of Growth in the Wheat Plant I. Seedling Growth and the Pattern of Growth at the Shoot Apex

“…This was clearly recognized in ontogenetic studies of wheat and Sudan grass by Ballard and Petrie (1936) and Petrie (1937), of oats by Williams (1936Williams ( , 1938Williams ( , 1948, of tobacco by Petrie, Watson, and Ward (1939), Watson and Petrie (1940), and Petrie and Arthur (1943), of flax by Tiver (1942), and of linseed by Tiver and Williams (1943). More recently, studies on similar lines have been made for barley and rye by Williams and Shapter (1955) and for the tomato plant by Gates (1955aGates ( , 1955bGates ( , 1957. Common features of all these studies are adequate sampling on from five to ten occasions during growth, the separation of the plants at least into their major parts, and the analysis of growth in terms of dry weight change.…”

Studies on the Growth of the Barley Apex I. Interrelationships Between Primordium Formation, Apex Length, .and Spikelet Development

“…Although increases in dry weight (Gates 1955a(Gates , 1955b and in stem length (Slatyer 1957) of tomato plants continue at relatively high levels of soil·moisture tension, Stocker (1960) has reviewed results of several workers showing, as is demon· strated here, a reduction in the rate of growth processes at slight soil-moisture deficits. But little information is available on the influence of soil·moisture tensions on morphological patterns and it seems appropriate to mention two such observations.…”

“…Observations on plants other than cereals have indicated the kind of information that might be profitably collected about inflorescence development under water stress. Thus the translocation of materials from the stem to the younger leaves at the shoot apex of a tomato plant is considered to be interrupted by drought (Gates 1955a(Gates , 1955b. In addition, floral initiation, and development of initiated flowers, in apricots have been shown to be delayed by soil-moisture stress (Brown 1953).…”

Physiological Significance of Internal Water Relations to Crop Yield

“…4-2 from Gates (1968) provides a good illustration of this point, using apical development of Lupin as experimental material. The virtual cessation of appearance of new primordia, as soon as stress was imposed, followed by renewed development upon relief of stress, is a phenomenon that has frequently been referred to in water stress literature (see for example Gates 1955aGates , 1968Slatyer, 1967).…”