Effect of Gypsum and Drought Stress on Maize (Zea mays L.). I. Growth, Light Absorption and Yield¹

Abstract

An experiment was designed to study the effect of gypsum and drought stress on growth, water status and yield with maize (Zea mays L.). Water status was assessed under field conditions by measurements of relative turgidity (RT) at noon. No stress was defined as RT greater than 90% — drought stress as RT less than 90%. A nostress crop was compared with a crop drought stressed for a period of 20 days during male meiosis and with a crop drought stressed during grain filling (after pollination to maturity). These treatments were set out in a randomised block design with a further comparison between the untreated sodic clay soil (control) and the same soil treated with gypsum. Gypsum and no‐stress conditions stimulated tiller production so that the final effective plant densities were above optimum. The no‐stress treatments produced large amounts of dry matter but this was channelled into sterile tillers rather than into grain. Drought stress during male meiosis stunted growth, stunted tassel development, reduced chlorophyll content and light absorption (during the period of stress) but, overall, was not very detrimental to grain yield. Drought stress during grain filling reduced grain yield by 50%; grain weight was reduced and a very high proportion of photosynthate went into sterile tillers.

Yield response of corn to deficit irrigation in a semiarid climate

“…Many researchers have evaluated the effect of stress timing on corn yield (Robins and Domingo, 1953;Denmead and Shaw, 1960;Barnes and Woolley, 1969;Downey, 1971;Claassen and Shaw, 1970;Jurgens et al, 1978;NeSmith and Ritchie, 1992;Bryant et al, 1992;Jama and Ottman, 1993). Others have developed models to quantify the effect of stress timing on yield (Jensen, 1968;Nairizi and Rydzewski, 1977;Doorenbos et al, 1979;Doorenbos and Kassam, 1979;Meyer et al, 1993aMeyer et al, , 1993b.…”

Corn yield response to moisture stress and foliar fertilizer during grain fill

“…The common observation in the above reports is that corn grain production is most sen sitive to moisture stress during the silking period. This has also been observed by others (Downey, 1971;Coligado et al, 1963;Volodarskii and Zinevich, 1960). Shaw (1977aShaw ( , 1977b summarizes the results of several researchers who estimate yield reduction due to moisture stress and shows a mean yield reduction of 3% per day of stress before silking, 7% during silking, and 4% during the grain filling period.…”

“…The number of seeds per plant was reduced by the first stress period, but growing conditions were good throughout the remainder of the growing season. Seed size compensation has been reported by others (Claassen and Shaw, 1970b;Downey, 1971;Wilson, 1968a). The extent of compensation by increasing seed size is, however, not large enough to fully compensate for the substantial loss in seed num bers.…”

“…Wilson (1968a) found that stress as late as three weeks after silking resulted in both a 30% decrease in seed number and a 30% decrease in seed size. Downey (1971) observed a decrease in seed size resulting from late stress. Boyer (1976) showed that desiccation during grain fill brought on quick reduction in photosynthesis, but grain yield, though reduced, was not reduced as severely as was dry matter production during the grain-filling period.…”

“…Stress during the vegetative stage resulted in the largest total yield but from fewer and larger seeds than in the controls. Downey (1971) observed that early stress reduced the number of seeds per cob and showed a small compensation in seed size.…”