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  • Author or Editor: Jerald W. Riekels x
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Abstract

Field experiments were conducted on organic soil for 2 years to evaluate the influence of frequent irrigation and topdressings with N on growth, maturity and storage life of onions (Allium cepa L.). With no irrigation, growth to midseason, maturity, and final yield were not influenced by increasing amounts of N. The growth to midseason, and the final yield increased and maturity was earlier with increasing amounts of N applied to onions receiving 5 cm of rainfall + irrigation per week. Sprouting in storage was earlier with high N and latest with no N or with the low N rates. The effect was greater with irrigation.

Onions did not respond to N topdressing without irrigation even though rainfall was regular. With irrigation, the highest yield and earliest maturity was obtained with 22 or 34 kg of N/ha applied whenever the crop received 10 cm of water. No advantage in yield or maturity was obtained by applying N after mid-July. Maturity was earlier without irrigation regardless of N treatment.

Open Access

Abstract

Field experiments were conducted on organic soil for 3 years using relatively high rates of N to evaluate the influence of N on the growth and maturity of onions. In 2 years with low rainfall, maturity was not influenced, but yields declined with increasing rates of N. The decline in yield was originally attributed to ammonium toxicity, but observations with 3 sources of N indicated that high concn of fertilizer salts also could have caused injury to the plants.

With high rainfall, yields increased with each increase in N, and as much as 240 lb. of N/acre was required for normal growth and maturation, while those onions receiving less than 120 lb. of N/acre were deficient in N and failed to mature properly. Utilizing different methods of incorporating N in the soil to evaluate the toxic response to N was unsuccessful in the wet season. Some indication of injury to the young seedlings occurred with the highest rates of N banded beneath the row, but these symptoms disappeared during subsequent periods of high rainfall.

Open Access

Abstract

Soaking tomato seeds in MnS04 solutions of concentrations greater than 0.5 and 1 M MnS04 inhibited germination during treatment without affecting the viability of the seeds. The emergence and early growth of tomato seedlings and the emergence of onion seedlings in soil was greater using seeds previously treated with 1 M MnS04 than with untreated seeds or with seeds treated with 2 and 2.5 M MnS04. These treatments had no effect on onion seedling growth. Soaking seeds in 1 M MnS04 was effective in supplying the Mn requirements of tomato plants grown in Mn deficient solutions for Approx 40 days. Shorter periods of normal growth were obtained by treating the seeds with less than 1 M concn of MnS04.

The amount of Mn retained after desorption and washing was greater with each increase in the soaking temp (0, 10, 20, and 30°C). A substantial amount of the Mn retained by the tomato and onion seeds after soaking appeared to be located on the seed coat or in the “outer space” of the tissue. With onion seeds, an additional portion of the Mn retained after soaking was located on the exchange sites of the seeds.

Open Access