Competition between maize and Rottboellia exaltata

Abstract

SUMMARYOne pot and five field experiments were made to study different aspects of the competition between R. exaltata and maize.The growth of young maize plants was not inhibited by being grown together in pots with young R. exaltata plants. In the field the soil tended to be somewhat wetter when the two species were grown together than when maize was grown alone, and was wettest with R. exaltata grown alone. Maize grain and total yield decreased and shoot yield of R. exaltata increased with R. exaltata plant density on both irrigated and unirrigated blocks of land, but yields were not much affected on either block by increase in plant density of maize or in nitrogen supply; maize yield was increased by irrigation but that of R. exaltata was not. Maize plant arrangement did not greatly affect maize grain and total yield or R. exaltata shoot yield, nor did arrangement of R. exaltata plants have much influence on their depression of maize yield, but R. exaltata caused a greater decrease in the grain yield of a short than of a tall maize cultivar.R. exaltata plants germinating at the same time as the crop plants did not have much effect on maize grain yield if they were removed by 8 weeks after the seedlings emerged, but decreased it considerably if allowed to remain for 12 weeks or more; weeds sown 2 or more weeks after the maize emerged hardly grew and had little effect on maize yield. When maize and R. exaltata were grown together leaf area of the maize was little affected up to the time of flowering, but was decreased after flowering, while leaf area of the weed was greatly depressed. Up to 7–8 weeks after seedling emergence more of the ground area was covered by foliage when maize was grown with R. exaltata than when it was grown alone, but later the ground was completely covered by foliage in both cases. Dry weight of grain and shoot of maize increased and that of shoot of R. exaltata decreased when the weed plants were shortened with growth regulators.

Growth and yield of corn grain and green ear in competition with weeds

“…However, another aspect must be involved. The corn root system develops less in the presence of weeds (Thomas & Allison, 1975), as observed in the present work (Table 4). Consequently, a smaller corn root system due to the presence of weeds would be less efficient in absorbing nutrients.…”

“…2/ Means followed by the same letter on the rows are not different at 5% probability, by the Tukey's test. weeds were also observed by other authors (Thomas & Allison, 1975). There was a tendency of reduction of the corn root system in the last sampling, in both hoed and nonhoed plots.…”

“…Actually, the water content in corn plots containing weeds was higher than in weed-free plots (Thomas & Allison, 1975). In the presence of weeds, the development of water stress symptoms may not be caused by water availability, but by a reduced ability of the root system to absorb water.…”

Nitrogen doses and weed control via intercropping with gliricidia for corn production

“…But another aspect must be involved. Corn root system is less developed with weed presence (Thomas & Allison, 1975). Thus, a smaller corn root Table 2 -Mean green matter values of the above-ground part of weeds, ear height, and plant height of AG 1051 corn cultivar, as a function of weed control method and application of nitrogen doses system, due to weed presence, would be less efficient in nutrient absorption.…”

Effects of weed "Reestablishment" after hoeing on corn yields

“…The corn root system becomes less developed in the presence of weeds (Thomas & Allison, 1975). Consequently, a smaller corn root system due to the presence of weeds would be less efficient in absorbing nutrients and water.…”