Physiological Maturity in Wheat Based on Kernel Water and Dry Matter

Abstract

desiccants or windrowing) without reducing wheat yield, thereby providing better returns in double-crop systems. Estimation of the time of physiological maturity could be beneficialThe most precise method of determining the time of to avoid yield penalties due to lodging, sprouting, hail, and other harvest risks. The aim of our study was to evaluate a simple empirical physiological maturity in crops is to follow kernel dry relationship (model) to determine physiological maturity by simulta-matter accumulation after anthesis. By weighing ovenneously analyzing the water and dry matter dynamics of wheat kernels.dried samples after physiological maturity, a regression An experiment was conducted in which two cultivars with different model can be determined that calculates when that stage kernel mass potential were sown on four dates. Fresh and dry kernel was actually reached. Following this procedure, we can mass from different positions in the spike were measured twice weekly. normally tell when physiological maturity is reached noTo validate the regression model, measured and calculated data from earlier than 2 wk after it actually occurred, which does different cultivars, growing seasons, and kernel positions were comnot allow us to decide on the earliest possible harvest pared. A negative linear relationship between kernel dry matter (relatime. In addition, this methodology requires weighing tive to final kernel mass) and kernel water concentration was deterequipment that is not commonly available on most mined. This showed that in wheat, physiological maturity is reached at 37% of kernel water concentration. Validation of the regression farms. model was done using data from field experiments in Argentina and Development of alternative, simple methods to deter-Mexico, and from controlled-conditions experiments reported in the mine with a single measurement if a crop is at physiologiliterature. The regression model successfully simulated results from cal maturity would be useful. For example, the use of field experiments (r ϭ 0.98; P Ͻ 0.001). In addition, data from conthe milk line and black layer are an indirect but fretrolled-conditions experiments showed the same negative linear relaquently used indicator of physiological maturity in tionship between relative kernel dry matter and kernel water concenmaize (Muchow, 1990). In wheat (as in other crops), tration (slope ϭ Ϫ0.4), and the model achieved a good fit for measured there are no simple early visual morphological signs data (r ϭ 0.96; P Ͻ 0.001). This regression model is proposed for use strongly correlated, for a wide range of environmental by farmers and crop managers, who can simply measure grain humidity conditions, with the cessation of kernel dry matter accuwith grain moisture meters. mulation. The kernel water concentration (KWC; i.e., percentage of water in kernels) is a potentially useful trait. Farmers and crop managers can simply estimate 895

Comparative behavior of wheat and barley associated with field release and grain weight determination

“…The fact that barley reached PM at higher M C than wheat is relevant in the context of this study as it implies that barley may be sprayed with a desiccant herbicide earlier than wheat, further enlarging the difference between both cereals in field release for sowing soybeans. The M C PM found in the present study for wheat does match pretty well previous reported values (Calderini et al, 2000;Pepler et al, 2006). On the other hand, in the case of barley the results of the present study (48%) differed from those reported by Bingham et al (2007b) (40%).…”

“…We found barley to have significantly higher MWC and M C PM than wheat. The difference in MWC may well explain the commonly reported higher potential grain weight of barley respect to wheat (Dreccer et al, 1997;Abeledo et al, 2002Abeledo et al, , 2003Calderini et al, 2000;Ehdaie et al, 2008). The fact that barley reached PM at higher M C than wheat is relevant in the context of this study as it implies that barley may be sprayed with a desiccant herbicide earlier than wheat, further enlarging the difference between both cereals in field release for sowing soybeans.…”

“…As grain moisture concentration at physiological maturity seems similar for wheat (38%; Calderini et al, 2000) and barley (40%; Bingham et al, 2007b), differences in grain-filling duration would mainly depend on grain water loss. Although there is information available on grain water dynamics in wheat and barley (Schnyder and Baum, 1992;Calderini et al, 2000;Savin et al, 1997;Bingham et al, 2007b) there is virtually no comparison on these dynamics between these species growing simultaneously under different environments. Grain growth could be considered as controlled by either the supply of photo-assimilates (source limitation) or the capacity of the grains to accumulate available carbohydrates (sink limitation).…”

Development of Seed Physiological Quality in Winter Oilseed Rape (Brassica napus L.) Cultivars

“…Seed moisture content of winter oilseed rape cultivars at mass maturity stage was high (41-50%), similar to that reported for wheat (37-39%) (Schnyder and Baum, 1992;Calderini et al, 2000), maize (35-36%) Borras and Westgate, 2006), soybean (60%) (Fraser et al, 1982) and sunflower (38%) (Rondanini et al, 2007). However, maximum seed quality of winter oilseed rape cultivars was obtained 10 to 22 days after mass maturity, depending on cultivar and quality test (Fig.…”

Dry matter and water dynamics of wheat grains in response to source reduction at different phases of grain filling

“…Given that grain water content has been found to be a key trait in determining wheat grain weight (Egli, 1990;Saini and Westgate, 2000;Pepler et al, 2006, Hasan et al, 2011, and considering the close balance between water and DM in growing grains (Schnyder and Baum, 1992;Calderini et al, 2000;Saini and Westgate, 2000;Pepler et al, 2006), studying grain water content in response to the source-sink reduction during grain filling could provide useful information on grain growth and its responsiveness to source constraints of wheat as has been shown in maize (Borrás et al, 2003;Borrás and Westgate, 2006).…”