Influence of Preceding Winter Crops and Irrigation Intervals on Rice Treated With Humic and Ascorbic Acids in North Delta

Abstract

A field experiments were conducted at Tag El-Ezz Agric, Res. Station, Dakahlia governorate Egypt, during the two successive summer seasons of 2005 and 2006 to study the effect of three preceding winter crops (flax, sugar beet and faba bean), three irrigation intervals (every 4, 6 and 8 days) in addition to humic (HA) & ascorbic acids (AA) on growth and yield of rice(sakha 101). The main results could be summarized as follows: Preceding winter crops, irrigation intervals and humic & ascorbic acids had a significant effect on all studied characters in both seasons. Grain yield of rice grown after faba bean attained increase 17.4 and 13% (average of two seasons) compared to rice grown after flax and sugar beet, respectively. Irrigation of rice fields every 6 days recorded the highest values in all studied characters in both seasons expect plant height and straw yield/fad. Irrigation every 6 days increased yield/fad by 4.4 and 21.4% compared to every 4 and 8 day respectively. Application of ascorbic acid gave the highest mean values in all studied characters in both seasons, which attained increase in grain yield reached to 9.3 and 3.8 % compared to control and humic acid, respectively. The highest grain yield (4.87 and 4.97 ton/fad) was recorded by the interaction among cultivation after faba bean, irrigated every 6 days and spraying by ascorbic acid. The relationship between grain yield from one side and its attributing variables on the other side was done using correlation, multiple linear regression and stepwise regression. The simple correlation coefficient cleared significant positive correlation between grain yield t/fad and each of individual studied characters, also cleared that there was significant positive correlation among all characters that were studied and each of other. Multiple regression analysis indicated that the relative contribution for all characters were 91.67 % from the total variation for yield t/fad. Results of stepwise regression analysis revealed that four out of nine variables contributed by 91.55 % in the total variation for yield t/fad. These variables were flag leaf area, 1000-grain weight, filled grains % and number of grains/panicles with R 2 being 89.67, 1.15, 0.40 and 0.73 %, respectively.