African Crop Science Journal African Crop Science Society ISSN: 1021-9730 EISSN: 2072-6589 Vol. 4, Num. 2, 1996, pp. 177-184

The response of 'Rosecoco' beans to aluminium treatment

E. N. MUGAI and S. G. AGONG

Department of Horticulture, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000 Nairobi, Kenya

(Received 3 June, 1995; accepted 27 October, 1995)

Code Number: CS96055
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ABSTRACT

Rosecoco beans (Phaseolus vulgaris L.) grown in sand culture at nine aluminium (Al) concentrations (0, 2, 4, 6, 10, 20, 50, 80 and 100 ppm Al) had their growth significantly influenced between 4 and 10 ppm Al. Germination and nodulation were reduced by Al at 80 ppm and above which complete inhibition of nodulation was observed. Calcium uptake in leaves increased with increasing Al content in the nutrient solution and positively corresponded to the amount of Al accumulated in the leaves possibly as a result of extreme K deficiency. Phosphorus uptake by the plant substantially decreased with the increased Al uptake. Potassium displayed a less consistent relationship with increasing Al level. The maximum K content in the plant tissue was attained at only 2 ppm before a decline between 6 and 50 ppm Al and an increase at 80 ppm was noted. The K level shot up at this stage probably due to concentration caused by reduced plant growth. It is concluded from this study that small amounts (2 to 4 ppm) of Al may not be detrimental for the germination, nodulation and mineral nutrition in the bean. Consequently, Rosecoco beans may be suitable for increasing agricultural production in acid affected soils of moderate aluminium concentrations.

Key Words: Phaseolus vulgaris, Aluminium tolerance, germination, mineral nutrition, nodulation

RESUME

La croissance des haricots rosecoco (Phaseolus vulgaris L.) cultives dans le sable, e neuf concentrations d'aluminium (0, 2, 4, 6, 10, 20, 50, 80 et 100 ppm Al), etait influencee d'une faon significative par des concentrations d'aluminium entre 4 et 10 ppm. La germination et la nodulation etaient reduites par 80 ppm d'aluminium et la nodulation etait inhibee par des concentrations encore plus elevees. L'absorption de calcium dans les feuilles augmentait quand la quantite d'aluminium augmentait dans la solution nutritive et ceci correspondait de faon positive e la quantite d'aluminium accumulee dans les feuilles probablement e cause d'une extreme deficience de potassium. L'assimiliation de phosphore par la plante diminue substantiellement avec l'augmentation de celle d'aluminium. Le potassium a une relation moins lineaire avec l'augmentation du niveau d'aluminium. La quantite maximale de K dans la plante etait obtenu e 2ppm d'aluminium avant de diminuer entre 6 et 50ppm d'aluminium, alors qu' une nouvelle augmentation etait observee e 80ppm d'aluminium. L'augmentation du niveau de K e ce moment etait probablement causee par la reduction de la croissance de la plante. Cette etude permet de conclure que de petites quantites (2 e 4ppm) d'aluminium n'ont pas d'influences nefastes sur la germination, la nodulation et la nutrition minerale des haricots resecoco. Par consequent, ces haricots peuvent tre utilises pour augmenter la production agricole dans les sols acides ou dans des sols avec des concentrations d'aluminium moderees.

Mots Cles: Phaseolus vulgaris, tolerance en aluminium, germination, nutrition minerale, nodulation

INTRODUCTION

Under a tropical climate, soil acidity and, in consequence, aluminium (Al) toxicity is a major constraint to the production of food crops (Horst and Klotz, 1990; Manrique, 1993). Among other effects, Al inhibits plant growth and reduces the capacity of plants to exploit soil water and nutrients. The reclamation of soils having high acidity and toxic Al concentrations is greatly restricted in the developing countries due to limited economic potential (Furlani and Bastos, 1990). Breeding for Al tolerance is therefore vital for improving crop production on acid soils and is an attractive, ecologically sound approach to exploit these soils (Furlani and Bastos, 1990; Llugany et al., 1994).

Common beans (Phaseolus vulgaris L.) form an important source of protein for most of the people in developing countries. The ÔRosecocoÕ common bean variety is widely grown and popular with most farmers in Kenya because of its taste and good cooking properties. This bean type has been grown in East Africa for nearly a century, and an experimental cultivar was released in Kenya in 1970 as variety GLP2 (Anon., 1973). Unlike for soybean (Foy et al., 1969) and snapbeans (Page et al., 1982) little is known about the toxicity of Al to the bean cultivars available to farmers in the East Africa region. The objectives of this study were, therefore, to: study the effect of aluminium on germination of Rosecoco bean and develop recommendations on the critical limits; evaluate the levels of aluminium at which nodulation is most affected; determine the distribution of Al, P, K, and Ca in the different plant parts as influenced by the Al treatment; and typify the symptoms associated with aluminium toxicity to young Rosecoco beans.

MATERIALS AND METHODS

The experiment was conducted between September 1993 and October of 1994 at the Jomo Kenyatta University of Agriculture and Technology. A sand-culture screening procedure was utilised to evaluate the response of Rosecoco bean variety to Al treatment. The benefits of using this culture have been shown by Horst and Klotz (1990). Ten rhizobium inoculated Rosecoco bean seeds were directly sown in acid washed sand in a 26-cm diameter plastic pot. The experiment was laid out in a three-replicate completely randomised block design under glass house conditions. The Al solution at 0, 2, 4, 6, 10, 20, 50, 80, and 100 ppm Al together with a half-strength nutrient solution were used to water the seeds till germination when the latter solution was reverted to full strength. The nutrient solution comprised of macronutrients [0.7 mM (NH4)2SO4, 2.3 mM KH2PO4, 4.5 mM Ca(NO3)2.4H2O and 2.3 mM MgSO4 . 7H2O], and the micronutrients included 2 ppm Fe, 0.5 ppm B, 0.01 ppm Mo, 0.01 ppm Zn, 0.01 ppm Cu and 0.4 ppm Mn supplied as Fe-Citrate, H3BO3, (NH4)6M07O24.4H2O, ZnSO4.7H2O, CuSO4.5H2O and MnSO4H2O, respectively (Shive and Robbins, 1937). The Al treatment were supplied in the form AlCl3.6H2O. The irrigation solution was always adjusted to, and maintained at, a pH value of 4.5 using hydrochloric acid and sodium hydroxide solutions. The seed and seedlings were supplied with 150 ml of the irrigating solution each day. The sand was flushed with distilled water every seven days during the entire experimental period.

Germination of seeds was assessed from the day cotyledons started emerging until the tenth day. On the tenth day, following emergence, the seedlings were thinned out leaving only three uniform plants per pot. When the plants attained 30 days, they were harvested and the sand washed off the roots under tap water. The shoots were excised from the roots and their fresh weights determined after which both plant parts were rinsed in distilled water. The nodules on roots were counted, then the plant tops and roots were dried in a forced air oven at 80 C for 24 hours after which dry matter yield was determined. The shoots and roots were separately ground to pass through a 1-mm sieve, then a sample was ashed in muffle furnace at 550 C for 5 hours. The ash was analysed for Al, P, K and Ca in the shoot and for Al in the root. Aluminium and P were determined according to the procedures of Chapman and Pratt (1961) and Westerman (1990). Flame photometry and atomic absorption spectrophotometry were utilised for the determination of K and Ca, respectively (Page et al., 1982).

The data obtained were subjected to anaysis of variance (ANOVA) and the means between the treatments separated using Fisher's Least Significance Difference (LSD) at P < 0.05 as described by Steel and Torrie (1981).

RESULTS

The germination of Rosecoco beans showed a decrease at 80 ppm Al, with the most severe effect being observed as Al concentration approached 100 ppm (Table 1). Subsequent growth of the young seedlings was slowed by the higher concentrations of Al, and it was observed that although some seeds germinated the total emergence of cotyledons and the opening up processes were also similarly reduced at Al contents of 80 ppm and above.

Growth of Rosecoco beans under the different levels of Al showed that shoot length of 30 days old plants was reduced by 48% at Al concentration of 100 ppm (Fig. 1). The plants, however, tolerated fairly high Al levels in the range of 2 and 20 ppm. Nodulation also responded variably to Al (Fig. 2), and Al concentration of 10 ppm and above resulted into a pronounced reduction in nodulation. Changes of up to 100% (total failure in nodulation) were noted with aluminium concentration of 80 ppm and above.

There was a consistent reduction in the shoot yield from 20 ppm Al concentration and above (Table 2). Visually, plants grown in higher aluminium concentrations (>20 ppm Al) showed stunted growth and chlorosis appearing initially on the leaf margins but later becoming necrotic in the older leaves. The young leaves were generally small and uniformly chlorotic with a rough feel. At 100 ppm Al, some plants failed to develop more than two true leaves as at final harvest. Root yield also displayed a trend similar to that of the shoot (Table 2). Notably, the increasing Al concentration significantly reduced root production at 80 ppm Al. The roots were also visually observed to be impeded and turned blackish in color at Al concentrations of 50 ppm and above.

Table 1

Figure 1. Effects of aluminium on the stem length (cm) of Rosecoco beans.

Figure 2

Table 2

Aluminium has been reported to stimulate plant growth (Foy et al., 1972). However, inhibition of sustainable root system seems to explain the retardation in plant growth through reduced nutrient and water uptake by the plants. The reduction in root dry matter yield related strongly to both fresh and dry shoot yields (Table 2). It is apparent that Al toxicity affected plant growth and development primarily through impairment of the root system. Similar observations have been reported with different plant species (Clarkson, 1966; Morimura and Masumoto, 1978; Horst et al., 1983; Horst and Klotz, 1990). It was, however, not clear whether Al depressed the root system through a reduction of cell division or elongation of these cells and/or a combination of both processes. Although sand-culture experiment may not adequately reflect the field conditions (Horst and Klotz, 1990), Rosecoco beans may be considered fairly tolerant to aluminium toxicity compared to some tropical grasses such as Hyparrhenia rufa and Cenchrus ciliaris whose dry matter production is reduced by as much as 40 and 90%, respectively, at only 4 ppm Al in water culture (Wallace et al., 1966).

Figure 3

Figure 4

Positive correlation of Ca accumulation in the shoot with increasing Al concentration contrasted with previous results (Foy et al., 1969). This might have been caused by an extreme K deficiency resulting from this unusual Ca/Al relationship. Also, Al tolerance in Rosecoco beans seems to be related to increased Ca uptake through which the excessive Al may be detoxified (Wallace et al., 1966). At high level Al treatment (80 ppm Al and above), some elements, for example K, showed correspondingly higher accumulation in the shoot. It is probable that reduction in plant growth was relatively faster compared to the mineral accumulation through which this parity may be explained.

The initial amount of those elements may also affect their uptake. The initial Ca concentration in the irrigation solution was registered at 180 ppm whereas Foy et al. (1972) had 80 ppm Ca. This initial concentration difference in Ca may explain the different trends in the accumulation of this element in the two parallel studies.

In conclusion, a small amount of Al in the range of 2 to 10 ppm may be beneficial to Rosecoco beans. It would be important, however, to evaluate the available Al in the acid soils of Kenya. In Brazil, for example, the exchangeable Al in oxisols of pH 4.6 has been quoted at 0.75 m.e 100g-1 soil (Wallace et al., 1966). This is equivalent to 202 and 101 ppm Al in soil and available Al, respectively, assuming that an equilibrium does exist between the adsorbed aluminium and that in the soil solution. The roots and shoots were significantly affected by Al concentration of 20 and 50 ppm, respectively. It follows, therefore, that soils of Al concentrations in the range of 100 ppm and above are likely to adversely affect the growth of Rosecoco beans. Plant biomass and Al contents in the roots seem to be better parameters for screening against aluminium toxicity in beans than the relative nutrient levels.

REFERENCES

Anonymous. 1973. Annual Report. Ministry of Agriculture, Kenya.

Chapman, H.D. and Pratt, P.F. 1961. Methods of Analysis for Soil, Plants and Water. California University, California.

Clarkson, D. T. 1966. Effect of aluminium on the uptake and metabolism of phosphorus by barley seeds. Plant Physiology 41:165-172.

Foy, C.D., Fleming, A.L. and Al Arminger, W.H. 1969. Aluminium tolerance of soybean varieties. Agronomy Journal 61:505-511.

Foy, C.D., Fleming, A.L. and Gerloff, G.C. 1972. Differential aluminium tolerance in two snapbean varieties. Agronomy Journal 64: 815-818.

Furlani, P.R. and Bastos, C.R. 1990. Genetic control of aluminium tolerance in sorghum. In: Genetic Aspects of Plant Nutrition. El Bassam, N., Dambroth, M. and Loughman, B.C. (Eds.), pp. 215-219. Kluwer Academic Publishers, the Netherlands.

Hortst, W. J., Wagner, A. and Marschner, H. 1983. Effect of aluminium and mineral element contents in roots of Vigna unguiculata genotypes. Z. Pflanzenphysiol 109:95-103.

Horst, W. J. and Klotz, F. 1990. Screening for aluminium tolerance and adaptation to acid soils. In: Genetic Aspects of Plant Nutrition. El Bassam, N., Dambroth, M. and Loughman, B.C. (Eds.), pp. 355-360. Kluwer Academic Publishers, the Netherlands.

Llugany, M., Massot, N., Wissemeier, A.H., Poschenrieder, C., Horst, W. J. and Barcelo, J. 1994. Aluminium tolerance of maize cultivars as assessed by callose production and root elongation. Zeitschrift fur Pflanzenernahrung und Bodenkunde 157: 447-451.

Manrique, L.A. 1993. Crop production in the tropics: a review. Journal of Plant Nutrition 16:1485-1516.

Morimura, S. and Masumoto, H. 1978. Effect of aluminium on some properties and template activity of purified pea DNA. Plant Cell Physiology 19:429-439.

Page, A.L., Miller, R.H. and Keeney, D.R. 1982. Methods of Soil Analysis. Part 2. Agronomy, Madison, Wisconsin, USA.

Sanchez, P.A. and Salinas, J.G. 1981. Low Input Technology for Managing Oxisols and Ultisols in Tropical America. Academic Press, Inc., New York.

Shive, J. W. and Robbins, W. R. 1937. Method of growing plants in solution and sand cultures. New Jersey Experimental Station Bulletin 636:3-24.

Steel, R.G.D. and Torrie, J.H. 1981. Principles and Procedures of Statistics. 2nd ed. McGraw-Hill, Singapore.

Wallace, A., Flolich, E. and Lunt, O. K. 1966. Calcium requirements of higher plants. Nature 209:634.

Westerman, R. L. 1990. Soil Testing and Plant Analysis. Third edition. Soil Science Society of America Book Series 3. Soil Science Society of America, Inc. Madison, Wisconsin, USA.

Copyright 1996 The African Crop Science Society

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