STUDIES ON THE NUTRITIONAL REQUIRE MENTS OF CHRYSANTHEMUMS

Transcription

1 FLORIDA STATE HORTICULTURAL SOCIETY, STUDIES ON THE NUTRITIONAL REQUIRE MENTS OF CHRYSANTHEMUMS S. S. Woltz Gulf Coast Experiment Station radenton The chrysanthemum crop is becoming in creasingly important in Florida. The acreage planted to chrysanthemums in the state has increased rapidly from less than five acres in the season to more than acres in the season (). Most of the in formation available to growers on fertilizing chrysanthemums has come from areas outside the state of Florida. While this information, together with growers' experience and experi mentation, has allowed production of high yields of chrysanthemums of high quality, there is need for clarification of the effects of various methods of fertilization, irrigation and liming upon the yield and quality of this in tensively cultivated crop. This paper is a re port of preliminary sand culture experiments on effects of variations in nutrient levels upon the growth of chrysanthemums. Literature Review Hill, et al () in Canada favored a : nitrogen to potash ratio for chrysanthemums. Lack of bloom coloration was associated with low levels of potassium and high calcium, magnesium and phosphorus. ost and ell () found that excess sulfate of ammonia caused wilting of chrysanthemums on sunny days. Excess muriate of potash caused a slight stunting of plants. Excess nitrate of soda caused chlorotic areas to appear on the younger leaves. When high levels of muriate of potash and nitrate of soda were added to gether, plants became chlorotic and died due to excess fertilizer salts. Waygood () found, particularly in the early stages of growth in nutrient solutions, that tomatoes grew well at the highest concentration of nutrients em ployed while chrysanthemums grew best at the lowest level. rofanek, et al () reported, somewhat to the contrary, that chrysanthemums of the ramer variety were relatively tolerant to saline conditions due to excess fertilizer salts in sandy soil. High salt content decreased stem length but did not greatly decrease dry weight. When salinity was due to ammonium or magnesium salts, stem length was greatly reduced. High levels of ammonium reduced dry weight. High salt levels from balanced nutrients decreased keeping quality while high calcium in the soil increased keeping quality. Materials and Methods Two plants each of Fortyniner and Gold smith varieties* were set out in gallon glazed ceramic pots containing washed quartz sand, December,. Artificial lighting was not employed. lants were pinched De cember. From December until January, plants were watered every other day with ml. per pot of a dilute nutrient solution containing nitrogen from ammonium nitrate and potassium and phosphorus, both from potassium dihydrogen phosphate. On January, application of dif ferential solutions was begun, gradually in creasing the amount applied per pot to ml. per day. The standard nutrient solution is shown below Element N Ca Mg Mo Zn Source % NaN, % NHJNfO NaHO % C, % SO CaCl MgSCX HO SO Versenol SO Na MoO, ZnSO Variations were made in each nutrient series over a wide range, using single pot cultures and the same nutrient sources as for the standard solution. lant measurement data are presented in Table. An inspection of the data for the Rooted cuttings were furnished by Yoder ros., Inc., of arberton, Ohio.

2 WOLTZ: CHRYSANTHEMUMS four control cultures indicates that the weight measurement is the most uniform criterion for the evaluation of the effects of various levels of nutrients. Although this experiment is nonreplicated and observational it is considered, owing to the uniformity of growth of chrysan themum plants and also to the wide differ ence between treatments in a series, that the data provide preliminary, useful information on the approximate levels of nutrients desir able for optimum growth. The nutrient con tents of the plant tissues can thus be correlated with major responses to changes in nutrient levels in solutions. All data in this paper repre sent averages or totals for two chrysanthemum varieties. lant tissue analytical data, averages for Fortyniner and Goldsmith, are shown in Figs. to for the elements varied in the experiment and are to be correlated in an ap proximate manner with the yield data in Table to obtain an indication of the levels of each nutrient required for optimum growth and also the levels at which adverse effects result. The data on desirable levels of nutrients in plant tissue will be considered only as ap proximate guides until better criteria are available. The correlation is aided by visible differences that existed in the plants over the very wide range of levels employed. In the nitrogen series (Table and Fig. ), the lower levels at which maximum growth occurred appeared to be between and. Leaf analysis indicated the need for about. to. percent nitrogen for the maximum production. Quality was slightly affected by nitrogen. It is concluded, therefore, that the nitrate to ammonia ratio employed, :, was quite satisfactory. Other experiments () have shown chrysanthemums to be severely damaged by an unbalance in terms of excess ammonia and, less so, in the case of excess nitrate. Nitrogen content was highest in leaves, next in buds and lowest in stems. The optimum level for phosphorus (Table ) was near the level. The next lower level,, did not yield as well while the higher level of produced a mild yel lowing of leaves that may have been due to an interference with iron nutrition. It is in teresting to note that the number of buds in bloom at harvest appeared to be increased stepwise up to the highest level of phosphorus. Corresponding to phosphorus in the solution is about. percent phosphorus in the leaves (Fig. ). It is considered, therefore, that leaf analysis near. percent phos phorus indicates ample availability of the ele ment at the time of sampling. At lower levels of phosphorus supply, the order of decreasing phosphorus content is buds, leaves and stems while at higher levels the leaves accumulate more than the buds. The lowest level of potassium (Table ) producing satisfactory plant response is be tween and. At lower levels potas sium deficiency was evidenced by dying of older leaves or in less severe cases by mar ginal necrosis of older leaves. Numbers of buds in bloom at harvest time was reduced by low levels of potassium as well as by low levels of nitrogen and phosphorus. lant analy sis (Fig. ) brings out an interesting point in that buds appear able to accumulate consid erable potassium at the low levels in the solu tion, at the expense of the leaves. At the level in the nutrient solution, the leaves contained more potassium than the buds. It

3 FLORIDA STATE HORTICULTURAL SOCIETY, magnesium (Fig. ) in the leaves. Leaves contained more magnesium than buds which in turn had more than stems. appears that the leaves of chrysanthemums should contain to percent potassium. Calcium deficiency was not produced (Table ) due to the presence of calcium in the cuttings and impurities in nutrient salts and water. The failure to produce severe cal cium deficiency is not considered as neces sarily indicating a low requirement for the ele ment although a similar experiment with gladiolus produced severe calcium deficiency. This portion of the experiment will be repeated with increased attention to possible sources of contamination. lant analysis (Fig. ) in " fcii* > XQ The most noteworthy fact about the boron series (Table ) is the toxic effect,of this element. oron toxicity, first marginal and then total necrosis, developed in the older leaves of the plants at the. level. There was boron (Fig. ) in the \ks SO &Q ttt S p fat dicated. percent in leaves at the nocalcium level. Calcium was accumulated decreasingly, in order, by leaves, buds and stems. Magnesium deficiency produced the cus tomary symptoms of interveinal chlorosis in the older leaves. lant response (Table ) was not greatly different, however, over the wide range of treatments employed. There was a trend toward greatest yield by weight at the and levels with about. percent leaves at this level. At the higher boron levels leaves were necrotic to the top of the stem and buds also showed injury. oron content of the foliage rose very rapidly with increasing levels in solutions. Chrysanthemums appear to be very effective in taking up boron from the substrate. Impurities contributed by pyrex glass, chemicals and water no doubt played a part. Copper at. (Table ) appeared adequate while apparently reduced yield by weight. The higher levels of and

4 WOLTZ: CHRYSANTHEMUMS were definitely toxic, producing a chlorotic condition in the foliage. Leaves at the level contained copper (Fig. ) which is a value higher than is normally found in plant tissue not contaminated with spray residues. * contained more than stems. It should be pointed out that total iron content is not gen erally accepted as a guide to the existence of a deficiency. Manganese (Table ) reduced yield when the level was raised to. In addition to a reduction in growth, it was noted that high levels of manganese, especially and produced a chlorotic condition, especially pro nounced in the younger leaves somewhat sim ilar to iron deficiency. It is well known that excesses of manganese and other heavy metals interfere with iron nutrition. The manganese content of leaves rose steadily (Fig. ) from to, the uptake of applied man ganese being very efficient. Goldsmith variety in the irondeficient cul ture as well as in the. iron treatment developed interveinal chlorosis indicating iron deficiency. This variety generally exhibits an interveinal chlorosis in plantings in Florida and also in other areas. It is concluded, there fore, that the physiology of this variety must be such as to result in a predisposition to iron deficiency that can be corrected by the ap plication of higher levels of chelated iron to the substrate than are required to prevent de ficiency in other varieties. Versenol toxicity (Table ) began at about iron as Ver senol and was expressed as a blackening of foliage together with reduced growth. Leaves (Fig. ) contained more iron than buds which The adverse effect from zinc took place (Table ) between and in the solu tions. Sixteen, however, had a greater de pressive effect on yield than did the same amount of manganese. There is a suggestion that yield was benefited by the lower levels of zinc. Zinc content of plants increased consid erably (Fig. ) with increasing zinc levels in the solution. Sixteen zinc was apparent ly so toxic that roots were damaged early and the zinc content of plant tops did not reach high levels due to inefficient uptake. Summary This observational experiment was carried out with single replications to obtain prelim inary indications of the nutritional require ment and tolerances of chrysanthemums. Nu trient levels were varied over wide ranges. Yield data and appearance of the growing

5 FLORIDA STATE HORTICULTURAL SOCIETY, Table. Treatments applied to Fortyniner and Goldsmith and data on sterna (total fresh weight, total number and average length) and number of buds in bloom at harvest. Treatment or ^nrinnt?resh vt. (grams) Number Avg.Length No. ads (laches) in bloom T j. '* *T I "J "T F p.. plants were used to select approximate opti mum levels for future sand culture experi ments, together with approximate levels or nutrients considered desirable in foliage, as shown below: Element g In Approximate eal arable Level Nutrient Solution (Snnd lture).... Leaves % The minor element contents of leaves cited above are considered ample and below the level of toxicity but are not considered to be critical levels. LITERATURE CITED. Hill, H., M.. Davis and F.. Johnson.. Nutritional studies with Chrysanthemums. Sci. Agri. :.. ofranek. A. M., O. R. Lunt and S. A. Hart.. Tolerance of Chrysanthemum morifolium varie ty ramer to saline conditions. roc. Am. Soc. Hort. Sci. :.. ost,. and R. S. ell.. Effect of excess fertilizers on roses, snapdragons and chrysanthe mums. roc. Am. Soc. Hort. Sci. :.. Smith, C. N. and D. L. rooke.. The Flori da chrysanthemum industry. Univ. of Fla. Ag. Econ. Mimeo. Rpt... Waygood, E. R.. A comparison of the nu trient requirements of tomato seedlings and mums. Canadian Florist :. Cr> "T'g Mg ' '? '«g?v Ou CU?e Mi Vn Mh a a Za a n.in q Zn. ^ ? S e R