Studies on potassium uptake and use efficiency of different cotton ...

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Ying Xia 1, 2, Cuncang Jiang 3, Xiao Wang 1 and Fang Chen 1, 4* ..... 77:7-15. 7Yang, X. E., Liu, J. X., Wang, W. M., Li, H., Luo, A. C., Ye, Z. Q. and. Yang, Y.
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Journal of Food, Agriculture & Environment Vol.11 (1): 472-476. 2013

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Studies on potassium uptake and use efficiency of different cotton (Gossypium hirsutum L.) genotypes by grafting Ying Xia 1, 2, Cuncang Jiang 3, Xiao Wang 1 and Fang Chen 1, 4* Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China. 2 Graduate University of Chinese Academy of Sciences, Beijing, 100049, China. 3 College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. 4China Program of the International Plant Nutrition Institute, Wuhan 430074, China. *e-mail: [email protected], [email protected] 1

Received 28 September 2012, accepted 18 January 2013.

Abstract Potassium uptake and use efficiency are mainly related to the mechanisms of potassium uptake in root system, potassium translocation and distribution to harvested parts of crop. Therefore, we used single and double grafting technologies for two different cotton genotypes (103, a high potassium efficiency genotype; 122, a low potassium efficiency genotype) to clarify the main mechanisms of cotton high K use efficiency. Dry matter accumulation (TDW), root to shoot ratio (R/S), vegetative to reproductive ratio (V/R), harvest index (HI), K use efficiency (KUE) and K accumulation in the total plant (TK) were evaluated. The results showed that the TDW, R/S, V/R, HI, as well as KUE for the scions 103 in 103/122 were higher than those sum values of 103 and 122 in (103+122)/122, whereas those traits for the scions 122 in 122/103 were lower than those sum values of 103 and 122 in (103+122)/103, indicated the cotton K use efficiency is mainly related to the K translocation and distribution within above ground organs and tissues. Similarly, the TK for the scions 103 in 103/122 was higher than those sum values of 103 and 122 in (103+122)/122, whereas the trait for the scions 122 in 122/103 was lower than those sum values of 103 and 122 in (103+122)/103, in addition, when the scions were same in the double grafting, the TK for the 103 rootstock was higher than 122 rootstock under K1 condition, indicating that the K uptake efficiency was determined by the root and shoot genotypes. Therefore, more dry matter and K translocated into shoot and reproductive organs could be one of the main mechanisms of cotton high K-use efficiency.

Key words: K uptake efficiency, K use efficiency, accumulation, partitioning, grafting.

Introduction Potassium (K) is one of the most important factors influencing crop metabolism, growth, development and yield 1. However, 3/4 of paddy soils in China are deficient in potassium, because of the limitation of potash resource in the country and the low K fertilizer use 2. Cotton (Gossypium hirsutum L.) is particularly sensitive to potassium deficiency, much more than many other crops 3, and potassium nutrition requirements of cotton cultivars may vary greatly 4. Therefore, screening a broad range of cotton genotypes to identify their differential K uptake and use efficiency is highly desirable 5. The K-efficient phenotype is a complex one comprising a mixture of uptake and utilization efficiency mechanisms. Potassium-uptake efficiency is governed by mechanisms relying on root architecture, high uptake capacity at the root surface as well as the capacity to mobilize non-exchangeable K by root exudates 2. K utilization could be considered in two prospective regarded as the economic response of a crop including yield and quality 3, 6. Yang et al. 7 reported that relative shoot biomass, relative root length, K concentration, and K accumulation in shoots and harvest index were the most important plant traits for identifying K-use-efficient genotypes for rice. Gerendás et al. 8 also pointed out that efficiency indicators based on total dry matter fail to provide an adequate picture when considering agronomic yield, unless the harvest index is maintained. 472

Grafting, has been widely used in the production of vegetables 9-13 to increase resistance to the stress from salts and heavy metals. As the usage of this technique increases, the purposes of grafting has been extended beyond the resistance to ever more frequent soil diseases 11, but the improvement of the nutrient efficiency in plants 14, 15. Ruiz et al. 14 reported that grafted plants improved NO3- assimilation and grafting tobacco plants could be used as a quick and effective method to improve nitrogen use efficiency (NUE). Grafted melon enhanced yield, NUE, and N uptake efficiency by 9%, 11.8%, and 16.3%, respectively, compared with the control 16. However, few reports that using grafting to evaluate the K efficiency on cotton genotypes was found. In this study we used the single and double grafting technology to separate the cotton root and shoot from a high K efficiency genotype 103 and a low K efficiency genotype 122, and aimed to investigate (1) what is the main mechanism of cotton high efficient use potassium? Is high uptake of K in root system or better distribution within the above ground part? (2) differences of the K uptake efficiency and translocation/distribution efficiency between the two genotypes. Materials and Methods Experimental design: The experiment was conducted in the greenhouse of Wuhan Botanical Garden, Chinese Academy of Journal of Food, Agriculture & Environment, Vol.11 (1), January 2013

Sciences (30°32.716' N, 114°24.996' E), from May to October in 2010. It consisted of two K fertilization rates: 0 (K0) and 0.46 g K (kg soil)-1 (K1). The two cotton (Gossypium hirsutum L.) cultivars (genotypes 122 and 103) were carefully screened from 86 cotton cultivars from 2001 to 2008 17-20. Genotype 103 represents high K use efficiency and high yield potential while genotype 122 represents the opposite. Each pot (height 28.0 cm × diameter 23.5 cm) was filled with 14 kg soil, which was classified as yellow brown soil. Soil analysis followed routine methods 21. Before use, the soil was air-dried and passed through a 2 mm sieve. Fertilizers used in the study were urea (46% N), calcium superphosphate (5% P), and potassium chloride (50% K). The application rates of fertilizer N, P and K were 0.66, 0.12 and 0.46 g kg-1 soil, respectively. Grafting procedures: Grafting was performed when seedlings had developed 2-3 true leaves. For the single grafting, 103 scions were grafted onto 122 rootstocks and 122 scions grafted onto 103 rootstocks (103/122 and 122/103), respectively. For the double grafting, the seedlings were cut down from the cotyledons, using the shoots of 103 and 122 as scions and the remaining plant part of 103 or 122 was used as rootstocks ((103+122)/ 103 and (103+122)/122), respectively. Grafting was made immediately after cutting the plants, and grafting clips were used to adhering the graft union. After the grafted plants had survived, they were transplanted to the plastic pots and placed in the greenhouse. There were 8 treatments with 4 replications and all arranged block randomly. Plant sampling and analysis: Four cotton plants per treatment were harvested on October 15 and were separated into roots, leaves, stems, boll sheds and lint. Then the samples except lint were dried at 60°C to determine their dry weight. Potassium concentration of the samples was extracted by H2SO4-H2O2, and determined by flame photometry 21. Statistical analysis: The following parameters were calculated according to biomass and K accumulation of various organs: Vegetative to reproductive ratio (V/R) = biomass of root, stem and leaf / biomass of boll shed and lint (1) Root to shoot ratio (R/S) = root biomass / shoot biomass

(2)

Harvest index (HI) = biomass of lint / total plant biomass

(3)

K use efficiency (KUE) = biomass of lint / K taken up of the plant

(4)

The data are presented as means ± SE of four replicates using the least significant difference (LSD) test to compare the grafting combinations at the 95% confidence level by the software statistical package for the social sciences (SPSS, Chicago, IL, USA) version 16.0. Figures were produced using Sigma Plot 10.0 system. Results Biomass accumulation: The effect of the scion on the dry matter weight was significant. For example, the TDW of 103 scions in graft combination of 103/122 were 26.0% and 14.8% higher compared with the sum values of 103 and 122 in (103+122)/122 combinations under K1 and K0 condition, Journal of Food, Agriculture & Environment, Vol.11 (1), January 2013

respectively. Similarly, the TDW of the sum values of 103 and 122 in (103+122)/103 were 21.9% and 34.4% higher compared with 122 scions in 122/103 under K1 and K0 condition, respectively. In addition, the lint of 103 scions in graft combination of 103/122 were 57.8% and 34.0% higher than the sum values of 103 and 122 in (103+122)/122 combinations under K1 and K0 condition, respectively, and this trait for the sum values of 103 and 122 in (103+122)/103 were 72.0% and 73.6% higher than 122 scions in 122/103 under K1 and K0 condition, respectively (Table 1). The above results indicated that the 103 scion gave the higher TDW and lint than 122 scions regardless of rootstock and K condition. Biomass partitioning: The R/S and V/R were also significantly affected by scions. The sum values of these traits for 103 and 122 scions in (103+122)/122 were higher than those of 103 scions in 103/122, though not marked for the R/S under K0 condition, whereas the sum values of these traits for 103 and 122 scions in (103+122)/103 were significantly lower compared with those values of 122 scions in 122/103 regardless of K condition (Fig. 1a, b), indicating that 103 exhibited higher shoot proportion and reproductive growth but lower root proportion and vegetative growth in the TDW, whereas 122 was in contrast. In contrast to the R/S and V/R, the sum values of HI for 103 and 122 scions in (103+122)/122 were lower than those of 103 scions in 103/122, however, the sum values of this trait for 103 and 122 scions in (103+122)/103 were significantly higher compared with those values of 122 scions in 122/103 regardless of K condition (Fig. 2). The results suggested that the scion genotype showed the greatest effect on the HI, and the scion genotype 103 exhibited higher HI than the scion genotype 122. K accumulation and partitioning: The rootstocks and scions both had effects on the TK in the grafts. The TK values of 103 scions in 103/122 were 20.6% and 17.0% higher than the sum values of 103 and 122 in (103+122)/122 under K1 and K0 condition, respectively. However, the TK values of 122 scions were 26.7% and 28.3% lower compared with the sum values of 103 and 122 in (103+122)/103 under K1 and K0 condition, respectively. When the scions were same with 103 and 122, the TK values of 103 rootstocks were 16.8% and 8.0% higher than 122 rootstocks under K1 and K0 condition, respectively (Table 2). The proportions of K partitioning to the vegetative organs of 103/122 were 13.4% and 1.1% lower, but to the reproductive organs were 13.4% and 1.1% higher than (103+122)/122 under K1 and K0 condition, respectively. Similarly, the proportions of K partitioning to the vegetative organs of 122/103 was 5.7% and

Table 1. Differences in the dry matter accumulation (g) in plant organs of the different grafts. K K1

Scion/rootstock 103/122 (103+122)/122 122/103 (103+122)/103

Root 10.7a 10.4a 11.3a 10.4a

Leaf 46.0a 28.7b 34.0b 35.5b

Stem 42.0b 49.5ab 44.2b 54.4a

Boll shed 24.9a 13.6bc 9.4c 15.0b

Lint 26.2a 16.6b 10.7c 18.4b

TDW 149.7a 118.8bc 109.7c 133.7b

K0

103/122 (103+122)/122 122/103 (103+122)/103

9.9a 10.8a 10.6a 11.0a

29.5a 24.8ab 19.6b 24.2ab

42.2ab 40.7ab 33.9b 43.3a

17.8a 13.0b 8.5c 15.6ab

21.3a 15.9b 8.7c 15.1b

120.7a 105.1b 81.3c 109.3ab

For each K condition, means within a column followed by the same letter are not significantly different according to L.S.D., p < 5%, n = 4.

473

0.20

R/S

0.15

0.10

103/122 (103+122)/122 122/103 (103+122)/103 ab a bc c

a b

19.2% higher, but to the reproductive organs were 5.7% and 19.2% lower than (103+122)/103 under K1 and K0 condition, respectively. K use efficiency: The KUE values of 103 scions in 103/122 were higher than those sum values of 103 and 122 in (103+122)/122 regardless of K condition, however, the trait for the 122 scions in 122/103 were lower than those sum values of 103 and 122 in (103+122)/103 regardless of K condition (Fig. 3).

a b

b

0.05

50 40

K1 5

K0

a

b

a b

4

b b

V/R

3

b

KUE (g DW [g K]-1)

0.00

a b

c

30

d 20

a

b

b c

10

c

c

103/122 (103+122)/122 122/103 (103+122)/103

0

2

K1

K0

Figure 3. Differences in K use efficiency (KUE) of the different grafts and K conditions.

1

For each K condition, means with the same letter are not significantly different according to L. S.D., p < 5%, n = 4.

0

K1

K0

Discussion Differences in the biomass accumulation, partitioning, and K use efficiency between the two genotypes: Many factors are able For each K condition, means with the same letter are not significantly different according to L.S.D., p < 5%, to influence yield, it was little affected by different rootstocks 22, n = 4. but the genotype of scion has major roles of the formation of 0.30 yield23. We discovered that the lint yield in the two contrasting 103/122 (103+122)/122 genotypes was largely related to the shoot, scion 103 has the 0.25 122/103 ability to produce the higher yield than scion 122 regardless of (103+122)/103 rootstock (Table 1), which was consistent with our previous a 0.20 a b results24, 25. b b b 0.15 Higher yields were associated with higher dry matter 26, 27. Unruh c c and Silvertooth 28 found that the lower yield genotype was 0.10 attributed to a smaller total dry matter and less efficient partitioning of dry matter into reproductive organs, therefore, the pattern of 0.05 accumulation of dry weight and the shoot, roots dry weight may 0.00 show the transport of particular nutrients and the partitioning of K1 K0 dry weight in the long term 29. Results in our study showed that Figure 2. Differences in harvest index (HI) of the different grafts and K the TDW for 103/122 was higher than the sum values of 103 and conditions. 122 in (103+122)/122 and the trait for the sum values of 103 and For each K condition, means with the same letter are not significantly different according to L.S.D., p < 5%, 122 in (103+122)/103 was higher than 122/103, suggesting that the n = 4. scion 103 gave the higher yield than the scion 122. Combined with the results that the scion 103 had lower R/S and V/R, but higher HI than those of scion 122 regardless of rootstocks (Figs Table 2. Differences in K accumulation (mg) in plant organs of the different 1 and 2). We can conclude that the scion 103 could grafts. compete for more photosynthate to the shoot than 122 K Scion/rootstock Root Leaf Stem Boll shed Lint TK when they grow on the same rootstock, and then K1 103/122 78.8a 517.3ab 189.8b 457.6a 146.2a 1389.7a transport to the reproductive organs, at last, transform (103+122)/122 69.0a 412.8b 323.5a 289.7b 57.3b 1152.2b the photosynthates in the reproductive organs into 122/103 66.7a 422.3b 330.2a 192.5c 49.9b 1061.6b economic index. The results were consistent with our (103+122)/103 63.7a 561.0a 337.5a 319.4b 63.9b 1345.5a previous study that more biomass was partitioned to 53.4a 50.5b 144.3a 256.5a 62.6a 567.4a K0 103/122 bolls rather than other organs contributed to higher (103+122)/122 56.3a 53.0b 107.7b 223.4a 44.4b 484.8bc cotton yield of genotype 103 24, 25. In a word, the cotton 122/103 56.6a 85.0a 130.9ab 113.3b 22.1c 407.9c yield, dry matter accumulation and partitioning were (103+122)/103 49.4a 74.2ab 125.6ab 230.4a 43.9b 523.5ab For each K condition, means within a column followed by the same letter are not significantly different according to L.S.D., not markedly affected by rootstock, suggesting that

HI

Figure 1. Differences in root shoot ratio (R/S) (a) and vegetative to reproductive ratio (V/R) (b) of the different grafts and K conditions.

p < 5%, n = 4.

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the critical difference on potassium use efficiency between the two genotypes was mainly in the above ground shoot rather than the root. KUE has been demonstrated to be a useful tool for assessing K use efficiency 7. According to the previous study, total dry matter weight and HI correlated highly with the KUE 6. In this study, the scion 103 showed markedly higher KUE than that of scion 122 regardless of the rootstock at the same K treatment (Fig. 3). This result indicated that produce more plant biomass and partition of biomass to the economic organs may be one of the main mechanisms for cotton higher K use efficiency. K accumulation and partitioning: Potassium uptake efficiency is the ability of plants to take up more K under low soil K availability. Uptake efficiency is often linked with the size of the root system30, 31 . Kodur et al. 32 reported that the differences between grapevines in the accumulation of K were largely due to rootstocks and the mechanisms of accumulation of K in scion are controlled by rootstocks. In our study, compared with the double grafted combinations with the same scions 103 and 122, the TK for 103 rootstocks were higher than those of 122 rootstocks, indicating that the ability for the absorption and transport of K of the 103 rootstock was stronger than the 122 rootstock under sufficient K condition. However, the TK for the scions 103 was higher than those of the scions 122 regardless of rootstocks and K condition (Table 2) with no significant differences in the root dry matter weight between the two rootstocks (Table 1). Combined with the previous study that neither root hair density nor root hair length correlated with plant K uptake 25, we can conclude that the mechanism in K uptake of the two genotypes was not only relied on the root system but the shoot, which was in agreement with the results that the vigour of both the scion and root system had an important role in the uptake and translocation of nutrients in grafted fruit trees 33. Ballesta et al. 34 also found that root system was not the only factor influencing the absorption and translocation of P in plants and the scion genotype must be taken into account also. With respect to K partitioning, the scion 103 showed markedly higher K in the reproductive organs but lower in the vegetative organs than the scion 122 (Table 2), which was in agreement with the previous study 24, indicating that the allocation of more K into lint could be one of the main mechanisms of high K-use efficiency 25. Conclusions The high K use efficiency genotype 103 showed higher yield as well as HI, KUE, and more dry matter in the shoot and the reproductive organs compare to low K use efficiency genotype 122. These result indicated that the mechanism of cotton high K use efficiency may greatly due to its high efficiencies on partitioning more dry matter and K to reproductive organs rather than absorbed more soil potassium by root system. References Zhao, D. L., Oosterhuis, D. M. and Bednarz, C. W. 2001. Influence of potassium deficiency on photosynthesis, chlorophyll content, and choloroplast ultrastructure of cotton plants. Photosynthetica 39:103-109. 2 Rengel, Z. and Damon, P. M. 2008. Crops and genotypes differ in efficiency of potassium uptake and use. Physiol. Plantarum 133:624-636. 1

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Cassman, K. G., Kerby, T. A., Roberts, B. A., Bryant, D. C. and Brouder, S. M. 1989. Differential response of two cotton cultivars to fertilizer and soil potassium. Agron. J. 81:870-876. 4 Bailey, J. C. and Gwathmey, C. O. 2007. Potassium effects on partitioning, yield, and earliness of contrasting cotton cultivars. Agron. J. 99:11301136. 5 Zia-ul-hassan, Arshad, M. and Khalid, A. 2011. Evaluating potassiumuse-efficient cotton genotypes using different ranking methods. J. Plant Nutri. 34:1957-1972. 6 George, M. S., Lu, G. Q. and Zhou, W. J. 2002. Genotypic variation for potassium uptake and utilization efficiency in sweet potato (Ipomoea batatas L.). Field Crops Res. 77:7-15. 7 Yang, X. E., Liu, J. X., Wang, W. M., Li, H., Luo, A. C., Ye, Z. Q. and Yang, Y. 2003. Genotypic differences and some associated plant traits in potassium internal use efficiency of lowland rice (Oryza sativa L.). Nutr. Cycl. Agroecosyst. 67:273-282. 8 Gerendás, J., Abbadi, J. and Sattelmacher, B. 2008. Potassium efficiency of safflower (Carthamus tinctorius L.) and sunflower (Helianthus annuus L.). J. Plant Nutri. Soil Sci. 171:431-439. 9 Yetisir, H. and Sari, N. 2003. Effect of different rootstock on plant growth, yield and quality of watermelon. Aust. J. Exp. Agri. 10:1269-1274. 10 Rodriguez, M. M. M., Estañ, M. T., Moyano, E., Abellan, J. O. G., Flores, F. B., Campos, J. F., Azzawi, M. J. A., Flowers, T. J. and Bolarín, M. C. 2008. The effectiveness of grafting to improve salt tolerance in tomato when an excluder genotype is used as scion. Environ. Exp. Bot. 63:392401. 11 Rouphael, Y., Cardarelli, M., Rea, E. and Colla, G. 2008. Grafting of cucumber as a means to minimize copper toxicity. Environ. Exp. Bot. 1:49-58. 12 Zhu, J., Bie, Z. L., Huang, Y. and Han, X. Y. 2008. Effect of grafting on the growth and ion concentrations of cucumber seedlings under NaCl stress. Soil Sci. Plant Nutr. 54:895-902. 13 Uygur, V. and Yetisir, H. 2009. Effects of rootstocks on some growth parameters, phosphorus and nitrogen uptake of watermelon under salt stress. J. Plant Nutr. 4:629-643. 14 Ruiz, J. M., Rivero, R. M., Cervilla, L. M., Castellano, R. and Romero, L. 2006. Grafting to improve nitrogen-use efficiency traits in tobacco plants. J. Sci. Food Agric. 86:1014-1021. 15 Foote, B. D. and Howell, R. W. 1964. Phosphorus tolerance and sensitivity of soybeans as related to uptake and translocation. Plant Physiol. 4:610-613. 16 Colla, G., Suarez, C. M. C., Cardarelli, M. and Rouphael, Y. 2010. Improving nitrogen use efficiency in melon by grafting. HortScience 4:559-565. 17 Jiang, C. C., Yuan, L. S. and Wang, Y H. 2003. K-efficiency in different cotton genotypes at seeding stage. J. HZAU. 22:564-568. 18 Jiang, C. C., Gao, X. Z. and Wang, Y. H. 2006. Response of difference potassium efficiency cotton genotypes to potassium deficiency. Cotton Sci. 18:109-114. 19 Jiang, C. C., Gao, X. Z. and Wang, Y. H. 2005. Study on the K efficiency differences and mechanisms of 2 cotton genotypes at seedling stage. Plant Nutr. Fert. Sci. 6:781-786. 20 Jiang, C. C., Chen, F., Gao, X. Z., Lu, J. W., Wan, K. Y., Nian, F. Z. and Wang, Y. H. 2008. Study on the nutrition characteristics of different K use efficiency cotton genotypes to K deficiency stress. Agri. Sci. China. 6:740-745. 21 Bao, S. D. 2000. Soil Agricultural-Chemical Analysis. China Agricultural Press, Beijing, China, 495 p. 22 Mannini, F., Lanati, D. and Lisa, A. 1992. Rootstock effect on ‘Grignolino’ vine nutrient level and must phenolic compounds and acidity. Quad. Vitic. Enol. Univ. 16:27-32. 23 Kocsis, L. and Lehoczky, E. 2000. The effect of the grape rootstockscion interaction on the potassium and calcium content of the leaves in connection with yield production. Commun. Soil Sci. Plant Anal. 31:11-14. 24 Xia, Y., Jiang, C. C., Chen, F., Lu, J. W. and Wang, Y. H. 2011. Differences 3

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in growth and potassium-use efficiency of two cotton genotypes. Commun. Soil Sci. Plan. 42:132-143. 25 Wang, L. and Chen, F. 2012. Genotypic variation of potassium uptake and use efficiency in cotton (Gossypium hirsutum L.). J. Plant Nutr. Soil Sci. 175:303–308. 26 Hasegawa, H. 2003. High yielding rice cultivars perform best even at reduced nitrogen fertilizer rate. Crop Sci. 43:921-926. 27 Pereira, M. L., Trápani, N. and Sadras, V. O. 2000. Genetic improvement of sunflower in Argentina between 1930 and 1995 Part III. Dry matter partitioning and grain composition. Field Crops Res. 67:215-221. 28 Unruh, B. L. and Silvertooth, J. C. 1996. Comparison between upland and a pima cotton cultivar. I. Growth and yield. Agron. J. 88:583-589. 29 Geiger, D. R. and Conti, T. R. 1983. Relation of increased potassium nutrition to photosynthesis and translocation of carbon. Plant Physiol. 71:141-144. 30 Dong, B., Rengel, Z. and Graham, R. D. 1995. Root morphology of wheat genotypes differing in zinc efficiency. J. Plant Nutr. 18:27612773. 31 Steingrobe, B. and Claassen, N. 2000. Potassium dynamics in the rhizosphere and K efficiency of crops. J. Plant Nutr. Soil Sci. 163:101106. 32 Kodur, S., Tisdall, J. M., Tang, C. and Walker, R. R. 2010 b. Accumulation of potassium in grapevine rootstocks (Vitis) grafted to Shiraz as affected by growth, root-traits and transpiration. Vitis 49:7-13. 33 Tagliavani, M., Bassi, D. and Marangoni, B. 1993. Growth and mineral nutrition of pear rootstocks in lime soils. Sci. Hortic. 54:13-22. 34 Ballesta, M. C. M., López, C. A., Muries, B., Cadenas, C. M. and Carvajal, M. 2010. Physiological aspects of rootstock scion interactions. Sci. Horti. 127:112-118.

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