engleski

Response of corn to potassium deficiency

Corn is plant with great needs for K. Low K supply was found in some soils situating in lowland of river Sava, Croatia. This problem is more actual in the last a few year period because considerable decrease of fertilizer consumption. Ameliorative K fertilization is recommended for overcome this problem, but choice of more tolerant hybrids to soil stress induced by K deficiency could be also reliable solution. Ten corn hybrids were grown under field conditions on powder clay loam (powder 64.08% and clay 34.5%) calcaric fluvisol (Zupanja area, Croatia) known to produce K deficiency symptoms in maize. Soil is neutral (pH in 1nKCl=7.19) and adequate humus content (3.14%). By EUF-method were found K deficiency and oversupplies of Mg and Ca (2.93 mg K, 24.2 mg Mg and 75.5 mg Ca/100 g of soil). Corn was sown at beginning of May 1998 at planned density (seed distance in row) in accordance to hybrid as follows: 22.5 cm (theoretical density: 62964 seeds/ha), 24.5 cm (58201) or 26.0 cm (54945). Fertilization was as follows (kg/ha): 197 N + 75P2O5 + 75 K2O. Ear-leaf samples were taken at silking stage. Plant samples were digested using cc HNO3+H2O2 and nutritional status were determined by ICP-AES. Corn grain yields were calculated on 90% theoretical plant density and 14% moisture basis. Mean grain yield in the trial (6.31 t/ha) was 38% lower than in the identical trial conducted at same period on normal soil (cambisol distanced 4 km by air-line: 10.25 t/ha). Considerable differences of corn yield were found among the hybrids from 3.61 to 9.59 t/ha. Four hybrids (OsSK568exp, OsSK602, OsSK444 and OsSK458exp.) could be designated as a more tolerant (mean yield 8.01 t/ha), four hybrids (OsSK552, OsSK554, OsSK508 and OsSK497exp.) less tolerant (mean yield 44.55 t/ha) to soil stress induced by K deficiency, while remaining two hybrids (OsSK382 and OsSK617exp.) are in mean range (6.45 t/ha). Stalk lodging incidences of individual hybrids were from 3.4% (OsSK444) to 65.9% (OsSK497exp.). Stalk lodging of two groups hybrids were as follows: 15.7% (the high yielding group) and 43% (the low yielding group), respectively. Mean ear-leaf composition were (% in dry matter) as follows: 2.97% N, 0.53%P, 0.64%K (acute K deficiency), 0.90% Ca and 1.28% Mg (moderate Mg oversupply). In general, differences among the hybrids were high significant and they were in ranges as follows: from 2.62 to 3.58% N, from 0.48 to 0.60% P, from 0.52 to 0.79% K, from 0.69 to 1.06% Ca and from 1.00 to 1.48% Mg. The hybrids characterizing low yield (OsSK552 and OsSK554: mean yield 3.93 t/ha) have very low ear-leaf K status (mean 0.55% K) and the higher levels of Ca (mean 1.01% Ca) and Mg (mean 1.47% Mg) in comparison with two hybrids of the high yields (OsSK568exp. and OsSK602: 8.80 t/ha, 0.74%K, 0.73% Ca and 1.13% Mg).

corn; potassium; deficiency

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