Effect of Water Stress and NPK Fertilisation on Growth and Resin Content of Grindelia camporum Greene

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1 Effect of Water Stress and NPK Fertilisation on Growth and Resin Content of Grindelia camporum Greene S.M. Mahmoud Associate professor of Floriculture Horticulture Department, Faculty of Agriculture Al Azher University, Naser City, Cairo, Egypt Keywords: gum weed, gum plant, irrigation, yield of, yield of dry mass Abstract Gum weed or gum plant (Grindelia camporum Greene - family Compositae) is a conspicuously resinous, herbaceous perennial species native to the arid regions. It grows well under harsh desert conditions with restricted amount of irrigation. Thus the plant appears to satisfy the requirements of a new crop for such an environment. In this experiments the optimal fertilisation doses and watering frequency of Grindelia were studied to improve its growth and resin content. In this concern, Grindelia were irrigated in 2, 4, 6 and 8 day intervals during the period of its vegetative growth. Furthermore, in separate experiment, N, P, and K fertilisers were used in 12N + 4P + 6K combinations, applying 0.5, 1.0, 2.0 and 4.0 g/pot dosages during the growing season. According to the results the limitation of the water supply - watering in 6 or 8 day intervals only, dramatically decreased the plant growth, the flower yield and the resin content of the plants. In addition, the plants, which were fertilised with high amount of NPK (2.0 and 4.0 g/pot) increased their height, dry mass, and yield of flower heads. Contrarily, the accumulation level of crude resin, percentage of resin acid were higher under lower levels of NPK fertilisation (1.0 and 2.0 g/pot). INTRODUCTION The arid lands of Egypt are partly utilised because of the severe ecological conditions. Any plant which can be grown in these regions would have economic importance. However, because of the shortage of water new crops of high droughttolerance with an economic value will be favoured over the other conventional crops that can not be produced without sufficient irrigation. Gum weed (Grindelia camporum Greene - family Compositae), which is a vigorous plant producing resin, may become one of the economical medicinal plants of this semi-arid region. The entire plant and the flower heads are used in medicine to treat bronchitis, asthma, whooping cough and kidney diseases (Lust, 1974). Duke and Wain (1981) recorded its antidote, antitussive, sedative, spasmolytic, and stimulant effects as well. Grindelia is a herbaceous perennial plant with stem up to 80 cm high with alternate, light green, oblong to lanceolate, coarsely-toothed and acute apex leaves. The inflorescence is a small resinous head with yellow surrounded by several rows of bracts (Grieve, 1980). The plant produces a diterpenoid resin on the surface of its stems, leaves and flower heads. Mahmoud (1993) estimated the percentages of crude resin in various parts of plants in Egyptian grown plant material. The amount of resin varied a great deal: flower head accumulated 17%, leaves 12.5%, stems 3%, roots and seeds negligible amounts. The main constituents of Grindelia resin are grindelic acid and its derivative oxygrindelic acid. Grindelia, a potential resin crop for arid lands was recorded by McLaughlin, (1985), Thompson et. al. (1996) and Revetta et. al. (1996). Although Grindelia grows well and produces market-quality resin under harsh desert condition with low irrigation supply, the crop yield is improved when regularly irrigated (McLaughlin, 1986). However, in a controlled greenhouse experiment conducted by Seliskar (1987), when Grindelia plants were grown under dry, average field water capacity and water saturated soil conditions, plant height, number of leaves and branches and above-ground bio-mass Proc. Int. Conf. on MAP Eds. J. Bernáth et al. Acta Hort. 576, ISHS

2 were maximum under average field capacity. In connection to fertilisation it was established that nitrogen promotes the growth and resin content of Grindelia. By the results of Mahmoud (1993) the urea treatment exhibited an obvious increase in plants growth, crude resin yield, resin acid % and resin amount/plant. In the present investigation we wanted to clear up, whether Grindelia as a medical and economical crop could grow under the arid and desert climate of Egypt. To achieve this goal the watering requirement and the suitable NPK fertilisation level of Grindelia were studied. MATERIALS AND METHODS Investigations were done at the Experimental Farm of the Horticulture Department, Faculty of Agriculture (Al Azhar University, Naser City, Cairo, Egypt) during the growing season of 1998/ Seeds of Grindelia camporum were obtained from University of Arizona in 1992 and propagated afterwards in the experimental field. Seeds were sown at the mid of October 1998 in nursery in shallow pots, carefully covered with a thin layer of soil, kept on a lath house and irrigated successively until emergence. Seedlings of proper size were transferred to 8 cm clay pots. Two groups of 35 cm diameter pots were filled by equal and homogeneous quantities of Nile silt and arranged in two groups, one for water stress experiment and the other for NPK fertilisation experiment. Each experiment was divided into four series of pots. Each one consisted of three replicates with ten pots each. Seedlings were transferred into the 35 cm pots when they had about four leaves and appeared ready for transplanting. In the first experiment, plants were subjected to four irrigation intervals of 2, 4, 6 and 8 days, during the growing season. In the second experiment N, P and K fertilisers were prepared using 12 N + 4 P + 6 K combinations, added in 0.5, 1.0, 2.0, and 4.0 g/ pots rates, monthly. For fertilisation ammonium sulphate (20.6% N), calcium super phosphate (15.5% P 2 O 2 ) and potassium sulphate (48% K 2 O) were used. The following data were recorded for each experiment : plants height, fresh and dry mass of herb and flower head. The time of, mass blooming and the length of period were recorded. Furthermore, 20 g of air-dried powder of plant material (leaves and ) were extracted exhaustively by CH 2 Cl 2 in Soxhlet according to method of Timmermann et. al. (1987). The following data were measured: - crude resin (CR) as the percent of the dry crude extract, acid number (AN) determined by titration with a standard aqueous solution of NaOH, resin acid percentage (RA%) calculated as grindelic acid by the formula : RA% = CR% X AN/ 160, total crude resin content/ plant (wt./ wt.). Both the water stress and NPK experiments were designed in a complete randomised blocks with three replicates. Data were statistically analysed. RESULTS AND DISCUSSION Effect of Water Regime on Gum Weed 1. Plant growth. The growth of Grindelia camporum, like most herbaceous perennials, displays a remarkable response to watering frequency. Plants showed a remarkable decrease in plant height, fresh and dry mass as a result of elongation of non-irrigated periods (Table 1). Plants which were irrigated every 8 days, gave the lowest values of plant height (57.33 cm), total fresh (134.7 g) and dry mass (44.56 g). However, the effect of irrigation repeated in every 4 days seemed to be optimal: the plants were highest (100.1 cm), and produced g fresh and g dry biomass. It is an interesting fact, that the high frequency of irrigation (in 2 days period) had an adverse effect. It is in harmony with results of Seliskar (1987), who reported that the production of Grindelia integerifolia was larger under the overall field water capacity conditions, than either in dry or saturated 290

3 soils. 2. Flowering. Flowering of Grindelia was obviously affected by watering. Values recorded in Tables 1 and 2 show a significant decline in production and number of if the period between irrigations were extended. Furthermore, Grindelia plants which were irrigated more frequently (2 and 4 day intervals) started to flower about 3-11 days earlier and the length of their period extended by about days. 3. Resin content. Resin content in Grindelia leaves and showed insignificant differences due to intervals of irrigation ( Table 3). However, some tendencies seemed to be obvious: both the resin acid % and crude resin in leaves and had a linear decrease as the watering intervals were increased. In addition, the highest production of crude resin (g/plant) was obtained from plants irrigated with short watering intervals, which is due to the fact that the short irrigation periods hastened the dry mass production of plants as well. This result is in harmony with statement of McLaughlin (1986), who confirmed, that the yield of Grindelia under harsh desert conditions can be promoted by irrigation. Effect of NPK Fertilisation on Gum Weed 1. Plant growth. No significant differences in plant height were detected between Grindelia plants due to the fertilisation treatment, yet there was a tendency for an increased height in plants that received a higher level of NPK fertiliser (Table 4). A similar trend was observed in the case of dry and fresh mass of plants and could be proved significantly. Thus, plants receiving 4.0 g/plant NPK dosage achieved the maximum production. 2. Flowering. Grindelia plants which received NPK fertilisation in high 4.0 g/plant dosage produced the highest number (157.85) of compared to the other treatments (Table 3). They produced the larger dry mass (48.5 g) of, too. In addition, Grindelia plants which received that high dosage (4.0 g/plant) started to flower later than the other NPK treated plant by about days, but it did not effect the length of the (Table 5). The plants, which were treated with high dosage of fertilisers had the longest period (90 days). 3. Resin content. The percentages of crude resin and resin acid in leaves and of Grindelia were found to decrease constantly as the rate of NPK fertilisation increased. In contrast, the amount of crude resin calculated by gram per plant took approximately an opposite trend. Plants, which received NPK fertilisation at high rates (4.0 g/plant) produced the highest amount of crude resin (Table 6). It is not a contradiction at all and due to the favourable effect of NPK fertilisation on biomass production. CONCLUSION The goal of this investigations was explore the feasibility of Grindelia camporum as a new crop for cultivation in the Egyptian desert where conventional crops can not be produced without irrigation and additional fertilisation. In practical terms, this research concentrated on studying the cultivation requirements of Grindelia, particularly its irrigation and fertilisation requirements. The results show that both extending or shortening the irrigation period to more or less than 4 day intervals will reduce both the plant growth and the flower production. The highest values of crude resin percentage as well as crude resin g/plant were achieved with the 4 day irrigation schedule. Plants receiving NPK fertilisation at rate of 4.0 g/plant achieved the maximum intensity of growth, as well as biomass and flower production. In spite of the fact that the percentage of crude resin and resin acid in leaves and were decreased constantly as a result of intensive fertilisation, their total yield showed surplus at the higher fertilisation rates, due to the intensive biomass production. ACKNOWLEDGEMENTS I would like to thank Mr. El Gohary, A. and Mr. Manssour, B. the MS post 291

4 graduate students, Branch of Medicinal Plants, Horticulture Department, Faculty of Agriculture, Azher University for offering help during the course of this investigation. Literature Cited Duke, J.A. and Wain, K.K Medicinal plants of the world. Computer index with more than 85,000 entries 3:1654. Grieve, M A Modern Herbal. Dover Publication, Inc., New York. Vol Lust, J The Herb Book. Bantam Books, Inc. New York. Mahmoud, S.M Influence of urea foliar spray on growth, and resin content of gum weed (Grindelia camorum Greene ) plant. Azher. J. Pharm. Sci. 12: McLaughlin, S.P Economic prospects for new crops in the South western United States. Economic Botany 39: McLaughlin, S.P Heritabilities of traits determining resin yield in gum weed. J. of Heredity 77: Revetta, D.A, Goffman, F., Pagano, E. and McLaughlin, S. P Grindelia chiloensis resin and biomass production in its native environment. Industrial Crops and Products 5(3): Seliskar, D.M The effect of soil moisture on structural and biomass characteristics of four salt marsh plants. J. of Exp. Botany 30(192): Thompson, A. Janick, E., and Simon, J.E Arid land industrial crops. Proceeding of the First National Symposium of New Crops, Indiana, USA Timmermann, B.N., McLaughlin, S.P. and Hoffmann, J.J Quantitative variation of grindeline diterpene acid in 20 species of north American Grindelia. Biochem. Syst. Ecol. 15(4): Tables Table 1. Effect of water regime on plant height, fresh and dry mass production of gum weed (Grindelia camporum Greene) Watering frequency (in days) Plant height (cm) Herb without Fresh mass (g) Dry mass ( g) Flowers Total Herb without Flowers Total % % Ns Table 2. Effect of water regime on of gum weed (Grindelia camporum Greene) Watering frequency (in days) Number of /plant Flowering ( by days) Mass End of Start of Mass % ns 12.9 Length of 1% ns

5 Table 3. Effect of water regime on resin content of gum weed (Grindelia camporum Greene) Watering frequency Crude resin (%) Acid number Resin acid (%) Crude resin (g/plant) (in days) Leave Flowe Leave Flowe Leave Flowe Leave Flowe Total s rs s rs s rs s rs % ns ns ns ns ns % ns ns ns ns ns Table 4. Effect of NPK fertilisation on plant height, fresh and dry mass of gum weed (Grindelia camporun Greene) NPK dosage (g/plant) Plant height (cm) Fresh mass ( gm ) Dry mass (g) Herb Flowers Total Herb Flowers Total without without % ns % ns Table 5. Effect of NPK fertilisation on of gum weed (Grindelia camporum Greene) NPK Number of /plant Flowering ( by days) dosage Mass End Start of Mass Length of (g/plant) of 0.5 g gm gm gm % ns ns 1% ns ns 293

6 Table 6. Effect of NPK fertilisation on resin content of gum weed (Grindelia camporum Greene) NPK dosage Crude resin (%) Acid number Resin acid ( %) Crude resin (g/plant) (g/plant) Leaves Flowers Leaves Flowers Leaves Flowers Leaves Flowers Total 0.5 gm gm gm gm % ns ns ns ns ns 1% ns ns ns 5.52 ns ns ns 294