Meiri, A., Inst. of Soils and Water, ARO, Bet-Dagan, 50250, Israel
Plaut, Z., Inst. of Soils and Water, ARO, Bet-Dagan, 50250, Israel

This review evaluates management practices that may minimize yield reduction under saline conditions according to three strategies: (I) control of root-zone salinity; (II) reduced damage to the crop; (III) reduced damage to individual plants. Plant response to salinity is described by an unchanged yield up to a threshold soil salinity (a), then a linear reduction in relative yield (b), to a maximum soil salinity that corresponds to zero yield (Yo). Strategies I and II do not take into consideration any change in the parameters of the response curve, while strategy III is aimed at modifying them. Control of root zone salinity is obtained by irrigation and leaching. From the review of existing data it is concluded that the effective soil salinity parameter should be taken as the mean electrical conductivity of the saturated paste extract or of the soil solution over time and space. Several irrigation and leaching practices are discussed. It is shown that intermittent leaching is more advantageous than leaching at each irrigation. Specific cultivation and irrigation practices that result in soil salinity reduction adjacent to young seedlings and the use of water of low salinity at specifically sensitive growth stages may be highly beneficial. Recent data do not show that reduced irrigation intervals improve crop response more under saline than under nonsaline irrigation. Alternate use of water of different salt concentrations results in mixing in the soil and the crop responds to the mean water salinity. Reduced damage at the fiel level when soil or irrigation water salinity is too high to maintain full yield of single plants requires a larger crop stand. For row crops reduced inter-row spacing is more effective than reduced intra-row spacing. Reduced damage at the plant level while the salinity tolerance of the plants remains constant shows up in the response curve parameters as larger threshold and slope and constant salinity at zero yield. This is the effect of a reduced atmospheric water demand that results in reduced stress in the plant under given salinity. Management can also change the salt tolerance of the crop. This will show up as higher salinity at zero yield, as well as changes in threshold and slope. Such changes in the response curve were found at different growth stages, under different atmospheric CO2, under different fertilization, and when sprinkler irrigation was compared with drip irrigation. © 1985 Martinus Nijhoff Publishers.