Efecto de la fecha de siembra y la disponibilidad hídrica sobre el rendimiento de soja

In the 2020-21 agricultural year, a soybean (Glycine max, L.) experiment was carried out at the Faculty of Agronomy. EEMAC ("Dr. Mario A. Cassinoni" Experimental Station), in Paysandú, Uruguay. The objective was to evaluate the effect of the planting date in a high potential short cycle crop under contrasting water conditions. The trial consisted of sowing on three sowing dates (SD) (October 10, November 10 and December 10) each under irrigation and drying conditions. The design used was complete random blocks in divided plots, the largest plot being the three planting dates and the smallest plot being the hydric condition (Irrigation and Rainfed), arranged randomly in the largest plot. Four repetitions were carried out with 6 treatments in each one distributed in 24 Experimental Units (EU). There was no SD interaction with water availability, where the irrigated treatments always yielded more than the dried ones. The SD of October, regardless of the SD, was the one that reached the maximum yields, 3936 kg.ha^-1, on the other hand, observing only the treatments under irrigation, it reached maximum yields of 5180 kg.ha^-1, followed by 3955 kg.ha^-1 and 4030 kg.ha^-1, for the SD of November and December respectively. These results are endorsed by NG. m-2 decreasing from the earliest to the latest SD, these being 3977, 2714 and 2483 for the October, November and December SD respectively. On the other hand, both in terms of NG m-2 and PMG, there was a year effect that there were no differences between November and December. The October SD under irrigation maintained a TCC of 180 kg DM. ha^-1.day^-1 during the reproductive period that accumulates the highest volume of DM at R6, 13831 kg. ha^-1 followed by 11081 and 8696 kg. ha^-1 for the SD of November and December respectively. The SD of November had the lowest CI, 31%, while the SD of October and December did not show differences, being 38% and 40% respectively. The October SD produced a lengthening of the total cycle, the duration of the critical period (PC) increased and its occurrences were brought forward in time. This left larger thermal sums and larger incident cumulative solar radiation (RS).