Relationships between shoot to root ratio, growth and leaf soluble protein concentration of Pisum sativum, Phaseolus vulgaris and Triticum aestivum under different nutrient deficiencies

Abstract

Relations between shoot to root dry weight ratio (S :RKey-words: Phaseolus vulgaris; Pisum sativum; Triticum aestivum; dry matter partitioning; macronutrients; nitrogen; pea; pinto bean; protein; wheat. INTRODUCTIONSupply of all macronutrients (N, P, S, K, Mg and Ca) can affect the partitioning of dry matter between shoot and root of higher plants. There is general agreement that shoot to root dry weight ratio (S : R) decreases when growth is limited by N supply (Andrews 1993), S supply (Clarkson, Saker & Purves 1989;Zsoldos et al. 1990;Ingestad & Ägren 1991) or P supply (Adalsteinsson & Jensen 1988;Fredeen, Rao & Terry 1989;Rufty, MacKown & Israel 1990;Ingestad & Ägren 1991;Cakmak, Hengeler & Marschner 1994). In contrast, S : R has been reported to decrease or increase with decreased growth associated with K deficiency (Asher & Ozanne 1967;Drew 1975;Steen 1984;Cakmak et al. 1994;Ericsson 1995), Mg deficiency (Will 1961;Cakmak et al. 1994;Ericsson & Kähr 1995) or Ca deficiency (Joham 1957;Ericsson 1995). There are reports for several higher plant species that S : R changes with growth/development independently of nutrient supply (Bastow-Wilson 1988;Gedroc, McConnaughay & Coleman 1996). Therefore, in some cases, the apparent response of S : R to nutrient supply may have been a growth/ontogenetic effect. Nevertheless, there are several studies which unequivocally show nutrient effects on S : R that are independent of growth/development (Andrews 1993;Cakmak et al. 1994).There is no general agreement as to the mechanism(s) of macronutrient effects on S : R. Bastow-Wilson (1988) reviewed models for the control of dry matter partitioning between shoot and root of higher plants and concluded that changes in S : R in response to a wide range of environmental factors, including macronutrient supply, conform to the Thornley (1972) model. In this model the factors which determine S : R are the supply of C and N substrates by shoot and root, respectively, transport of these substrates between shoot and root and incorporation of these substrates into plant structure. It was argued that structural growth of shoot and root is colimited by the local C and N substrate concentrations and that this growth acts as a sink for substrates to which further substrates diffuse from the points of supply. It was further argued that the rate of transport of C and N substrate from shoot to root and root to shoot, respectively, is proportional to the concentration gradient divided by a resistance. Hence, a decrease in C substrate acquisition would result in an increase in S : R while a decrease in N substrate acquisition would cause S : R to decrease.Dewar (1993) developed a model in which C, N and water interact to determine S : R. In this model it was assumed that a fraction of the N taken up by the root is translocated via the xylem to the shoot where it is transferred to the phloem. The remaining fraction is transferred directly to the root phloem. Phloem translocation of C and N downwards from shoot to root is driven by a shoot ...

Effects of water and nitrogen supply on growth, water-use efficiency and mucilage yield of isabgol (Plantago ovata Forsk)

“…N addition stimulated the growth of the isabgol under different soil water conditions, as reflecting by a significant increase in plant growth parameters such as leaf area, root and shoot growth, R/S ratio (Table 3). Similar reports of N addition on plant growth have been reported for isabgol (Karimzadeh and Omidbaigi, 2004;Arun et al, 2012) and other crops (Andrews et al, 1999;Ashraf et al, 2001;Puri and Swamy, 2001;Song et al., 2010;Binghua et al, 2012). The growth response of the plants to N addition and soil water suggested that N supply could amplify the positive effects of elevated soil moisture on plant growth (Puri and Swamy, 2001;Song et al, 2010 These results indicated that N addition might alleviate the negative effects of drought stress manipulation on whole-plant growth of the plant.…”

“…Therefore, many believed that nutrient stress may enhance the tolerance of plants to drought and possibly some other stresses as well (Palatova, 2002;Arora et al, 2001). In contrast, many other studies have noticed that increased N application could improve wateruse efficiency, alleviate drought stress effects on plant growth in arid systems by preventing cell membrane damage and enhancing osmoregulation (Andrews et al, 1999;Saneoka et al, 2004). In addition, no significant interactions between N supply and drought stress for root dry mass, root/shoot ratio and WUE have been also found (Song et al, 2010;Rahimi et al, 2011).…”

“…It is demonstrated that N addition might play a key role in maintaining plant productivity under different soil water conditions in the arid land. The ratio of root and shoot DM (R/S) was an indicator that represented demandsupply balance for environmental stresses (Andrews, 1999;Palatova, 2002). Nutrient limitation and drought stress were found to increase carbon translocation from the leaves to the roots, thereby increased the R/S ratio (Andrews et al, 1999;Poorter and Nagel, 1999).…”

“…The photosynthetic rate, chlorophyll content, and concentrations of proline and soluble sugar vary in plants subject to different moisture conditions and nutritional status. Drought stress can increase organic compounds required for osmotic adjustment, such as soluble sugars and proline (Andrews et al, 1999;Garg et al, 2001;Molinari et al, 2007).…”

AFestschriftin honour of Professor John A. Raven

“…One of us was fortunate enough to have had John as a lecturer at undergraduate level, as a Ph.D. supervisor, and then to have worked with him over the following 25 years building on some of his earlier work (e.g. Andrews et al 1984Andrews et al , 1999Andrews et al , 2005Andrews et al , 2009aRaven et al 2004Raven et al , 2005a. We highlight two areas of John's current research -firstly, 'Interactions among resources in the growth of phytoplankton', and secondly, 'The potential for photosynthesis on other planets'.…”