Seasonal changes in production and nutrient content ofCynodon dactylon (L.) Pers. subjected to water deficits

Abstract

Seasonal changes in water relations, production and mineral composition were studied in a sward of Cynodon dac~lon (L). Pers. subjected to water deficits during a dry summer, and at recovery in autumn. The experiment was carried out under Mediterranean field conditions. Water deficits during summer reduced total dry matter production by 60%, but in autumn there were no differences between treatments. Compared to well-watered sward, the sward grown under drought showed an increase in potassium, calcium and nitrogen of 55, 10 and 10% respectively. These differences decreased with the arrival of autumn rains. Leaf osmotic potential (~P~) fell during the dry summer to -2.8 MPa in well-watered plants and to -4.2 MPa in stressed plants. In autumn there were no differences between treatments. Nevertheless, relative water content (RWC) only decreased to 0.86 in droughted plants. In summer potassium contributed to the osmotic adjustment. In contrast, under water deficits a decrease of 71% in sodium and, to a lesser but significant extent decreases in phosphorus, magnesium and chlorine was observed. Nitrogen, phosphorus and sulphur showed low concentrations during summer and increased in autumn.Abbrev&tions: D-droughted plots, W-watered plots; RWC-relative water content, W -L e a f water potential; ~P~ -osmotic potential, D W -d r y weight

Synergistic Effect of Selenium Addition and Water Stress on <i>Melilotus officinalis</i> L. Mineral Content

“…Calcium, on the other hand, has a prominent role in maintaining cell structure (McLaughlin and Wimmer, 1999) and recovery after a period of water stress (Palta, 1990). Increase of Ca under water deficit has been reported by others (Utrillas et al, 1995;Patakas et al, 2002).…”

“…In compliance with this result, Kostopoulou et al (2010) in their study found that stomatal conductance of M. officinalis under similar experimental conditions was not affected by water deficit. On the other hand, little information is available on the effect of water stress on Na and Mg. A decrease in sodium content of Cynodon dactylon was also observed under water deficit conditions (Utrillas et al, 1995). On the contrary, plants of Sorghum bicolor grown on different irrigation regimes did not differ in the concentration of Na (Asgharipour and Heidari, 2011).…”

“…The difference in these results could be associated to several factors, as the experimental conditions, plant species and duration of water stress (Tennant and Wu, 2000). Potassium plays an important role in survival of plants under abiotic stress (Waraich et al, 2011), contributing to osmotic adjustment (Utrillas et al, 1995;Patakas et al, 2002). Leaf K increase could have contributed to the osmotic adjustment of M. officinalis plants, acting as a mechanism to maintain turgor pressure and stomatal conductance (Patakas et al, 2002) and, hence, photosynthesis under water stress conditions (Waraich et al, 2011).…”

Combined effects between temporal heterogeneity of water supply, nutrient level, and population density on biomass of four broadly distributed herbaceous species

“…Although the investigated species have different preferences for water availability (Grime et al 1988;Iwatsuki et al 1995;Utrillas et al 1995), in this study homogeneous water supply increased the biomass of all four species. Therefore, growth increments when the water supply has a homogeneous temporal pattern are a general trend in a large variety of herbaceous species (see also Fay et al 2003;Saeed and El-Nadi 1998;Sepaskhah and KamgarHaghighi 1997).…”

“…; and one legume, Trifolium repens L. All of these species are broadly distributed, and they can all grow in a common environment, despite their different water demands. Cynodon dactylon is a C4 plant that is tolerant of high temperatures and low water availability (Utrillas et al 1995). Lolium perenne is common in moist environments and less frequent in dry habitats, and T. repens is common in meadows and pastures and can be found even in dryland (Grime et al 1988).…”