RESPONSE OF CORN (Zea mays L.) INBRED LINES TO STRESS AND POTASSIUM FERTILIZATION ON K-FIXING SOIL

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ISSN 1330-7142

UDK = 633.15:631.811.314’6

RESPONSE OF CORN (

Zea mays

L.) INBRED LINES TO STRESS AND POTASSIUM

FERTILIZATION ON K-FIXING SOIL

V. Kovačević

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_{, I. Brkić}

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_{, D. Šimić}

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_{, B. Šimić}

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Original scientific paper

Izvorni znanstveni rad

SUMMARY

Potassium fixation and oversupply of magnesium are the main reasons for the appearance of potassium deficiency symptoms in maize plants, especially inbred lines, when grown on some drained gleysols of the Eastern Croatia. In the spring of 1990 field trial of increasing potash rates until 3250 K2O/ha was conducted.

For the next growing season residual influences of ameliorative fertilization were tested and experimental field was usually fertilized (for corn: 240 kg N + 125 kg P2O5 + 150 kg K2O/ha). In the growing season of

1993, different corn hybrids and inbred lines were grown on this place (four replications, experimental plot 18.2 m2). In this study, response of six inbred lines was shown. As affected by 3250 kg K2O/ha application,

they were increased grain yield by 112% and ear-leaf K (silking stage) by 200% compared to ordinary fertilization. At the same time, they decreased lodging incidence by 72% and ear-leaf Mg by 48%. Degree of inbred lines tolerance toward soil stress (ordinary fertilization) was different. For example, depending on inbred lines, grain yields ranged from 0.73 to 1.85 t/ha, lodging incidences from 3% to 51%, while ear-leaf composition ranged as follows (mg/100 g on dry matter basis): from 414 to 621 K, from 951 to 1458 Mg and from 751 to 1335 Ca. Analogous values on treatment of ameliorative K rate were as follows: 1.97-3.42 t/ha (yield); 3-24 % (lodging); from 1074 to 1907 K, from 442 to 1049 Mg and from 659 to 1203 Ca. In general, low connection was found between ear-leaf composition and degree of inbred lines tolerance toward soil stress.

Key- words: corn, nutritional stress, potassium, magnesium, calcium, potassium fertilization

INTRODUCTION

Eastern Croatia is an important area for seed-corn production because of relative favourable soil and climate characteristics. Prevailing arable lands of small size and their proprietorial relations, as well as need for space isolation of seed-corn crops (minimum 200 m apart from other corn crop) are main reasons for difficulties concerning finding of field characterizing normal soil fertility for seed corn growing. As different genotypes of same plant species are more or less susceptible to soil stress, we tested response of corn inbred lines to fertilization and degree of susceptibility to soil stress as affected by potassium (K) deficiency.

Potassium deficiency in connections with its strong fixation and magnesium excess are main reasons for reducing soil fertility of some gleysols of Croatia concerning corn growth (Bertić et al., 1989;

Kovačević and Vukadinović, 1992; Kovačević et al., 1990). Fertilization by the enormous quantities

of K was shown as acceptable solution, but by choice of more tolerant genotypes it is possible to

contribute to overcome this problem (Kovačević and Vujević, 1994). Testing of corn inbred lines

concerning degree of their tolerance to soil stress could be useful information concerning growing of seed-corn under these stress conditions.

MATERIAL AND METHODS

Field experiment __________________

(1) Prof.Ph.D Vlado Kovačević – Josip Juraj Strossmayer University of Osijek, Faculty of Agriculture, Trg Sv.Trojstva 3, HR-31000 Osijek, (2) Ph.D Ivan Brkić, Ph.D Domagoj Šimić and Ph.D Branimir Šimić -

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The field experiment with six rates of potassium fertilization (in KCl form as muriate of potash) to level of 3250 kg K2O/ha) was conducted in spring 1990 (March 30, 1990). It was conducted by

randomised block design in four replicates (experimental plot of fertilization was 294 m2) and in duplicate for two-field corn-soybeans (1990 and 1991)/sugar beet (1992) rotation. Residual influences of ameliorative KCl fertilization were tested in the next growing seasons and the experimental field was fertilized uniformly in level of ordinary fertilization (kg/ha for maize: 240 N + 125 P2O5 + 150

K2O). For the 1993 growing season corn was grown both fields. In the first field 12 corn hybrids and

in the second field 12 corn inbred lines (parents of commercial corn hybrids in production of their seed) were grown. Gross of the experimental plot of each hybrid/inbred line was 18.2 m2 or two 13-m long rows. The results of corn hybrids response were shown by Kovačević et al. (1996).

For the 1993 growing season, corn was sown on April 28 and harvested on September 24, 1993. Grain yields were calculated on theoretical plant density (48 750 plants of maternal component of seed-corn) with corrections for contribution of the female-sterile plants and 14% moisture basis.

Sampling

The ear-leaf samples (30 leaves in mean sample) were taken at the beginning of the silking stage (the middle of July) for chemical analysis. Fifteen cobs were taken (from the first replication only) for determinations of grain moisture at harvest time and for cob grain contribution. These data were used for transformation of cob weight of actual grain moisture to grain yield on 86% of dry matter.

Chemical analysis

For chemical analysis, choice of six inbred lines (in total 48 samples) and two levels of K fertilization (ordinary fertilization and application of 3250 kg K20 ha-1 three years ago) was made. This choice was

made based on degree of lodging tolerance (three tolerant lines: Os 86-39, Os 84-44 and Os 89-9; three susceptible lines: Os 89-9, Os 1-44 and Os 30-8). Dry ashing procedure (Isaak and Johnson, 1975) was used for plant material digestion (450oC overnight and multiple digestion of ash with nitric acid). Potassium, calcium and magnesium were determined in diluted filtrate by atomic absorption.

Soil and weather characteristics

Soil was classified as drained gleysol on calcareous loess substrate. Detail description of soil

characteristics was made by Kovačević and Vukadinović (1992). By the soil analysis (0-30 cm of depth) of the control treatment (ordinary K fertilization) they found values as follows: pH in 0.1 m KCl = 7.3; organic matter content = 2.4 %; carbonate content = 14.9 %; exchangeable K by 1n NH4

-acetate (pH = 7.0) solution = 5.6 mg K/ 100 g; lightly exchangeable Mg (CaCl2-method) = 37.6 mg

Mg 100 g-1; exchangeable calcium (NH4-acetate) = 603 mg Ca/ 100 g.

Weather conditions in the growing season of 1993 were less favourable for corn growing because of drought stress during two-month period (July and August). For example in four month period (May-August) average air-temperature was 20.5oC, while precipitation was 196 mm (the data of the Weather Bureau Đakovo: about eight km from the experimental field towards west). Although in two-month period total of 113 mm of rainfall was, their distribution was unfavourable because of long dry periods.

RESULTS AND DISCUSSION

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Table 1. Response of corn inbred lines to soil stress and potassium fertilization Tablica 1. Reakcija samooplodnih linija kukuruza na stres u tlu i gnojidbu kalijem

Fertilization -Gnojidba

(factor-A) kg K2O ha-1

Corn inbred line (factor B)

Samooplodna linija kukuruza (faktor B)

Average

Prosjek

(factor A)

Os 86-39 Os 84-44 Os 84-49 Os 89-9 Os 1-44 Os 30-8 Grain yield (t/ha on 14 % moisturebasis) - Prinos zrna /t/ha na bazi 14% vlage)

150 3250

Average B / Prosjek B

0.73 3.42 2.07 0.86 2.56 1.71 1.06 1.92 1.49 1.16 1.96 1.56 1.04 2.41 1.73 1.85 1.97 1.92 1.12 2.37 1.75 LSD 0.05 LSD 0.01 A: 0.13 0.23 B: 0.22 0.29 BxA:0.31 0.42 AxB: 0.32 0.47 The ear-leaf composition at silking stage (on dry matter basis)

Sastav suhe tvari lista ispod klipa u fazi svilanja

The ear-leaf potassium (mg K/ 100 g) - Kalij u listu ispod klipa (mg K/100 g)

150 3250 Average (B) 417 1074 745 559 1512 1036 414 1484 949 547 1171 859 621 1861 1241 479 1907 1193 506 1501 1004 LSD 0.05 LSD 0.01 A: 185 340 B: 88 118 BxA: 124 168 AxB: 232 404

The ear-leaf magnesium (mg Mg/100 g) - Magnezij u listu ispod klipa (mg Mg/100 g)

The ear-leaf calcium (mg Ca/ 100 g) - Kalcij u listu ispod klipa (mg Ca/100 g)

Stalk lodging (%) at maturity stage - Polijeganje stabljike (%) u zriobi

150 3250 37 5 41 24 51 3 7 3 6 3 3 3 24 7 Female-sterile plants contribution (%) - Udjel žensko-sterilnih biljaka (%)

150 3250 18 5 2 24 20 3 11 3 20 3 10 3 14 7

The most tolerant was inbred line Os 30-8 its grain yield was near 50% higher compared to average yield of remained five lines. Also, the fact is that by the most susceptible line Os 86-39 grain yield was near 5-fold increased due to K fertilization compared to the control, while the most tolerant line had similar yields on two levels of K supplies. Depending on inbred line (factor B) grain yields ranged from 1.49 to 2.07 t/ha. According to degree of statistical significance (LSD 0.01), two inbred lines (Os 86-39 and Os 30-8) were in the group of the higher yields (mean 2.00 t/ha) in comparison with remained four lines (mean 1.62 t/ha or about 20% lower). Potassium fertilization has been factor of stabilization of grain yield in function of genotype. For example, difference of yield among inbred lines were higher when grown on the control treatment: yield of the most susceptible line was 60 % lower compared to the most tolerant line. At the same time, difference by 44% was found by the analogous comparison on the K fertilization treatment.

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remained three susceptible lines to lodging (Os 86-39, Os 84-44 and Os 84-49) had mean of 463 mg K/100 g. Specificity of inbred lines concerning ear-leaf K uptake was more expressed under normal conditions of K supply (fertilization by the enormous K rate). For example, the lowest value of K uptake was under stress conditions 33% lower compared to the highest value, while by the analogous comparison of K fertilization treatment difference in range of 42 % was found.

Potassium fertilization was considerable factor of balance between K and Mg nutrition. For example, under stress conditions (K deficiency and Mg oversupply) excessive Mg uptaken by maize as well as unbalance between K and Mg in plants (in mean K/Mg = 0.43) was found, while as affected by K fertilization, these relations were considerably improved (K/Mg = 2.43). Depending on inbred line, they found differences in Mg uptake from 696 to 1254 mg Mg/100 g. With that regard, three tolerant inbred lines to lodging had mean higher Mg uptake (976 mg Mg/100 g) compared to three susceptible lines (819 mg K/100 g). The differences were also found in K uptake (1098 mg K and 910 mg K/100 g, for tolerant and susceptible inbred lines to lodging, respectively).

Also, they found differences in Ca uptaken by inbred lines by influences of both K fertilization and inheritance factors. For example, as affected by K fertilization, Ca uptaken by plants decreased in extent of 24%. Differences among inbred lines were from 690 to 1269 mg Ca/100 g. Concerning reduction of Ca uptake due to K fertilization, we found differences from 10% to 36% depending on inbred line.

As previous mentioned, choice of inbred lines for chemical analysis was made based on their degree of tolerance to lodging under stress conditions. Contribution to lodging was in mean 43% and 5% for susceptible and tolerant inbred lines, respectively (in mean 24% for six inbred lines under stress conditions). Lodging decreased to a range of 7% only as affected by applied fertilization. In spite of normal K supply, line Os 84-44 had contribution of lodging in extent of 24%, while by remained five lines it considerably reduced lodging to level under five percent only.

CONCLUSIONS

Grain yields of corn inbred lines and ear-leaf K, Mg and Ca contents were under influences of environmental and genetic factors. In general, under soil stress conditions induced by K deficiency and Mg oversupply, grain yields were in mean of 50% lower. By the ameliorative K fertilization relations between K and Mg uptaken by plants were improved. Inbred line Os 30-8 was most tolerant, while inbred line Os 86-39 was susceptible to soil stress. Inclination of inbred lines to lodging at maturity stage was under influences of inheritance but by normalization of K supply this property was eliminated. Growing of more tolerant inbred lines and increased K fertilization are directions for seed-corn production improvement on this soil type.

REFERENCES

1. Bergmann W. (1992): Nutritional disorders of plant development, visual and analytical diagnosis. Gustav Fischer Verlag Jena-Stuttgart-New York.

2. Bertić B., Vukadinović V., Kovačević V.(1989): Excess of magnesium uptake in maize plants as promoting factor of potassium deficiency. Magnesium-Bulletin 11(1): 25-27.

3. Isaak R. A., Johnson W. C. (1975): Colaborative study of wet and dry ashing techniques for the elemental analysis of plant tissue by AAS. JAOAC, 58:436-440.

4. Kovačević, V., Kadar I., Brkić I., Josipović M. (1996): Response of corn (Zea mays L.) hybrids to potassium fertilization on strong K-fixing soil. In: Proceedings of the IX Intern. Coll. for Optimization of Plant nutrition (IAOPN), Prague, Czech Republic, 8-15 September 1996, p. 458-461.

5. Kovačević V., Katušić V., Vukadinović, V. (1990): Nutritional stress of maize (Zea mays L.) growing on a gleysol of East Croatia. In: Plant Nutrition, Physiology and Applications. Kluwer Acad. Publ., Dordrecht, Boston, London, pp. 607-610.

6. Kovačević V., Vujević S. (1994): Magnesium uptake and lodging tolerance in maize (Zea mays L.) hybrids. In: Magnesium 1993, John Libbey & Company Ltd., pp. 99-104.

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REAKCIJA KUKURUZA (

Zea mays

L. ) NA STRES I GNOJIDBU KALIJEM NA TLU

S FIKSACIJOM KALIJA

SAŽETAK

Fiksacija kalija i višak magnezija glavni su razlozi za pojavu simptoma nedostatka kalija u kukuruzu, osobito samooplodnim linijama, kada se uzgajaju na dreniranom hipoglejnom tlu istočne Hrvatske. U proljeće 1990.

postavljen je gnojidbeni pokus u kome su primijenjene rastuće količine kalijevog klorida do 3250 K2O/ha.

Sljedećih godina praćeni su naknadni učinci takve gnojidbe i pokusna površina je gnojena standardno (za

kukuruz: 240 kg N + 125 kg P2O5 + 150 kg K2O/ha). Tijekom vegetacije 1993. uzgajani su na toj površini

različiti hibridi i samooplodne linije kukuruza (4 ponavljanja, veličina osnovne parcele 18,2 m2_{). U ovome je}

radu prikazana reakcija šest samooplodnih linija. Gnojidbom s 3250 kg K2O/ha povećan je prinos zrna za

112%, a sadržaj kalija u listu ispod klipa (faza svilanja) za 200% u usporedbi s kontrolom. U isto vrijeme opao je udjel poleglih biljaka u zriobi za 78%, a sadržaj magnezija u listu za 48%.

Stupanj otpornosti pojedinih samooplodnih linija prema stresu u tlu (standardna gnojidba) bio je različit. Tako je prinos zrna, ovisno o samooplodnoj liniji, varirao od 0,73 do 1,85 t/ha, polijeganje stabljike od 3% do 51%, dok je sastav lista ispod klipa (mg/100 g suhe tvari) bio u sljedećim rasponima: od 414 do 621 K, od 951 do 1458 Mg i od 751 do 1335 Ca. Analogne vrijednosti za tretman melioracijske gnojidbe kalijem bile su

sljedeće: od 1,97 do 3,42 t/ha (prinos), od 3 do 24 % (polijeganje), od 1074 do 1907 K, od 442 do 1049 Mg i od

659 do 1203 Ca. Općenito, slaba veza je ustanovljena između sastava lista i stupnja otpornosti samooplodnih

linija prema stresu u tlu izazvanom fiksacijom kalija.

Ključne riječi: kukuruz, hranidbeni stres, kalij, magnezij, kalcij, gnojidba kalijem

(Received on 18 July 2002; accepted on 9 September 2002 – Primljeno18. srpnja 2002.; prihvaćeno 9. rujna