Growth and Water Relations of Cereal Crops as Influenced by Salinity and Relative Humidity1

Abstract

AbstractCrop salt tolerance is not absolute but depends on environmental factors such as relative humidity (RH), as well as management of irrigation and fertility. The objective of this study was to evaluate the influence of atmospheric relative humidity on plant growth and how it interacts with salinity to influence salt tolerance and water relations of barley (Hordeum vulgaris L. ‘CM‐67’), wheat (Triticum aestivum L. ‘Siete Cerros’), and sweet corn (Zea mays L. ‘Bonanza’). The studies were conducted in sunlit climate chambers with temperatures cycled daily between 10 and 27 C for barley and wheat and between 17 and 32 C for corn and with average daytime RH controlled near 45% for the low and near 90% for the high RH treatments. The root medium of each crop was maintained at four different osmotic potentials (s Ψo), the range depending on the crop's salt tolerance. With a nonsaline root medium, increasing the RH from 45 to 90%, increased the wheat yield by 24%, had no influence on corn yield, and reduced barley yield by 16%. High RH increased the salt tolerance of barley and corn but did not affect the tolerance of wheat. For all three crops at all sΨo levels, water‐use efficiency (yield per unit of water consumed) was higher at 90% than at 45% RH. Linear relationships were found between leaf total water (LΨt) and osmotic (LΨo) potentials and sΨo for barley and wheat. Leaf pressure potential (LΨp) was reduced by low RH and salinity. The relationship between crop yield and LΨt was linear. The difference between full yield and almost no yield was 2.0 megaPascals for both barley and wheat. RH must be considered when evaluating the salt tolerance of barley and corn but not for wheat.