Efeito de épocas de semeadura no desenvolvimento e produtividade do trigo (Triticum aestivum L.) na região de Pato Branco-PR

Abstract

For each subperiod development of wheat are produced in different organs and is the formation of the number of these organs dependent on the duration of each subperiod. The temperature of the vernalization photoperiod and contribute significantly to determine the rate of development of the length of such sub-periods. In this context, this study aims to map the temporal variability of environmental factors in Pato Branco, and discuss its possible implications for the expression of yield potential of wheat. Also, we attempted to analyze the periods of the year that offer the best environmental conditions, in terms of temperature and solar radiation to define the increase in yield components and development of culture, seeking the best seasons to the cultivars studied. The experiment was conducted during the years 2008 and 2009 at the Experimental Station of Agronomy Course UTFPR in Pato Branco-PR (26º10'S; 52º41'W and 750 m). The experimental design was randomized blocks with three replications in the first year and four replications in the second year in a factorial scheme (BRS 208, BRS 220 and BRS Guamirim x seven sowing dates). The sowings were made in the period of: 06/05 17/05 31/05 14/06 28/06 12/07 and 26/07 for the year 2008 and 02/05 16/05, 02 / 06 13/06 30/06 13/07 24/07 for the year 2009. Thus, this study initially determined the different developmental sub periods of the wheat genotypes tested, so defined: SE-EM, EM-DA, DA-ET, ET-AN, AN-MF. The double ring stages and terminal spikelet were determined morphologically, 3 stalks harvested every 48 hours. To determine the physiological maturity, five central spikelets of three spikes, with 15 spikelets per plot were sampled every 72 hours and brought the oven, for after being weighed, considering the physiological maturity when they had constant weight. Also, we assessed the implications of QF yield of genotypes. The variables analyzed were: plant height, shoot dry weight and ear, harvest index and yield components (spikes m-2, spikelets spike-1, grains spikelet-1 and thousand grain weight). It is not clear effect was observed, photothermal quotient (QF) on the definition of component performance. For the year 2008 the subperiod AN-MF, was associated with increased grain yield, only for BRS 220, correlating with the later increase in QF and reflecting the increase in grain mass. For the year 2009 was not possible to observe correlations of yield with the thermal. However it was observed between the QF and the thermal sub-period of the AN-MF, for BRS Guamirim. The grain yield, this differed between the years of high rainfall (2009) with respect to years of low precipitation (2008). Cultivation procedures conducted on the dates of May 30 and June 14 showed higher grain yields for the years 2008 and 2009, respectively.