Water Deficit Timing Effects on Yield Components in Maize

Abstract

This study was designed to determine the interval of sensitivity of maize (Zea mays L.) yield components to moisture stress, and to evaluate that interval using estimates of plant available water (PAW). Individual maize plants were grown in containers in a glasshouse. For each treatment, water was withheld until the accumulated water use in well-watered control containers was 20 L, approximately twice the PAW in each container. Containers were well watered at all other times. Containers were weighed to determine water use rates and to estimate PAW. Moisture stress was assumed initiated when water use rates declined below the average for well-watered containers. The interval when kernel number was sensitive to moisture stress began 2 to 7 dafter silking and ended 16 to 22 dafter silking. Stress initiated prior to silking but relieved within 2 d after silking did not reduce kernel number, kernel weight, or plant yield. The fewest number of kernels, 45% of the control, occurred for stress during the 7-d period after silking. Kernel weight was reduced by stress during the grain filling period, and the lowest weight, 51% of the control, occurred for stress 12 to 16 d after silking. Water use rates in treatment plant containers were compared to estimates of the soil moisture stress index (SMI) determined as the percentage of PAW in the containers. Water use rates declined when SMI declined below thresholds of between 0.20 and 0.30. These thresholds were similar to those reported for other crops. Thus, this analysis demonstrated that parameters based on PAW can be useful for evaluating the timing of moisture stress on maize yield components.

Changes in gene expression in maize kernel in response to water and salt stress

“…In maize, drought at pollination induces yield reductions 2-3-fold higher compared to drought periods at other developmental stages (Grant et al 1989). Early plant responses to environmental stresses include gens involved in perception of the environmental change and signal transduction to initiate biochemical and physiological responses, together with expression of the genes responsible for these responses.…”

Response of Maize to Nutrients Foliar Application Under Water Deficit Stress Conditions

“…Developing ovaries appear to be weak sinks and will fail if there are insufficient new (concurrent) photosynthates available for their growth [2,30] . Alternatively water stress may prevent ovary fertilization by reducing silk receptivity [2] , or low kernel at ear potential may cause kernel growth to cease prematurely [15,30] . This latter effect may lead to a reduced HI even if water stress occurs late in the grain filling stage.…”

Correlation of Growth Parameters with Yield of Two Cassava Varieties

“…Furthermore, cassava products are also popular in international trade, contributing to the economy of the exporting countries (Scott et al, 2000). However, the results and performance of important crops may be affected by genetic as well as vorius environmental factors which could be linked to inclement temperatures, water deficit, inefficient distribution of assimilates in favor of he root and time of harvest (Grant et al, 1985;Chang, 1991). The productivity of cassava is also limited by soil nutrient status, increased yield due to fertilizer application has been severaly reported (Fermont et al, 2010;.Okpara et al, 2010;Edet et al, 2013).…”