Effect of growing site and agronomy on the dynamics of water content in the grain yield of maize hybrids

Grain filling is a decisive stage for the successfulness of maize productio n. It is this stage that determines the size of yield and the moisture cont ent of the yield. In the experiments measurements were made on the dry matt er content of the grain yield in hybrids belonging to various maturity grou ps, and the dynamics of water content was analysed as a function of year, g rowing site and production technology. In the present paper the effects of growing site and production technology are discussed. The experiment was located in Debrecen from 1991 to 1994 and in Debrecen, N agyhorcsok and Orbotytyan in 1998. The examinations were made on maize hybr ids grown in Hungary (Dekalb 524 SC, Pi 3732 SC and Volga SC in 1991-1994 a nd Anita SC, Debreceni 351 SC and Maraton SC in 1998). Among the production technology factors, the effects of mineral fertilisation (control and N:P: K = 60:46:54 kg/ha) and plant density (48 and 71 thousand/ha) are presented . The effect of the growing site was evaluated in 1998 by carrying out the experiments with the same production technology at three locations (Debrece n, Nagyhorcsok, Orbottyan). In the course of statistical evaluations (regression and covariance analysi s) the rare of change in the water content or dry matter was compared with the effect heat sum (T-b = 8 degrees C) after flowering. Effect of location: At each of the locations the drying down rate of the th ree hybrids, from different maturity groups, as a function of the effective heat sum, could be characterised by a joint regression coefficient. A join t regression equation could not be applied to the water content dynamics of the three hybrids due to differences in the maturity date. At the two loca tions favourable for maize (Debrecen and Nagyhorcsok) the drying down rate of the hybrids could be characterised by a joint regression coefficient; th e deviation was not significant. On the sandy soil with poor water manageme nt in Orbottyan the dry weather (drought stress) significantly accelerated the drying down of the hybrids examined, compared to the grain yield at fav ourable growing sites. Effect of production technology factors: Under the given experimental condi tions mineral fertilisation did not have a uniform effect on the rate of mo isture content reduction due to the very substantial variety(x)weather(x) ( x)fertilization interaction. The effect of plant density could he demonstra ted by means of correlation calculations, but covariance analysis only show ed a significant change in the rate of drying: down in Orbottyan. This indi cates that strong interactions should again be expected.