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The potential for improvement of N utilization in corn (Zea mays L.) can depend on the existence of genotypic differences. Accordingly studies were conducted to determine if N translocation from the leaves and stalk to the ear during the period immediately following silking depended on the genotype. In 1970, the N concentration of individual leaf blades, stalk, and developing ears of four inbreds was determined at the silking stage and 14 and 28 days after silking. In a similar experiment in 1971, using bulked leaf blade samples, three of the inbreds plus their F1 hybrids were analyzed for N at silking and 24 days after silking. In 1970, the apparent translocation of N from individual leaf blades differed considerably depending on the inbred Significant differences in N concentration in either the stalks or developing ears occurred among genotypes in 1970 and 1971. Appreciable differences were found in the apparent propensity of the inbreds to translocate N to the developing ear. In 1970, apparent N translocation during the 14 to 28 day period was greater than during the first 14 days following silking. The inbreds differed between years with respect to apparent N translocation suggesting a genotype ✕ environment interaction. The N accumulation rate following silking was substantially greater in one of the three F1 hybrids than in the parent inbreds. Thus there appears to be some potential for the screening and development of hybrids capable of accumulating a relatively large quantity of N or using N more efficiently through translocation from various plant parts.

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No abstract

In three of five cases, tassel removal from corn (Zea mays L.) at or near tassel emergence increased grain yields. The increase was larger and more consistent at higher populations. When leaf tissue was removed with the tassel, yields were decreased, although this effect was smaller at higher populations. A large portion of the yield response from detasseling resulted from the elimination of tassel light interception. Simulated small tassel size (produced by tassel side branch removal) resulted in increased grain yields.