الفهرس 
Effect of rice varietiesOnly 14 pages are availabe for public view
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Abstract
The present investigation was carried out at the Experimental station Farm of the Faculty of Agriculture, Tanta University at Kafk El- Sheikh during 1993 and 1994 summer seasons . This investigation aimed to study the effect of zinc application and levels, sources, and time of nitrogen application on growth , grain quality and yield and its components of rice. This work was studied under the following two parts: 1- Effect of nitrogen and zinc application on growth and yield of three rice varieties. 11- Effect of sources and time of nitrogen application and zinc application on growth and yield of rice ( var. Giza 176 ). A strip- split plot design with four replications was used in all experiments. In the first part the first main plots were randomly assigned to three rice varieties i. e. Giza 177, GZ 1368 and Giza 176, while the second main plots received two nitrogen levels i. e. 40 and 60 kg Nlfed. The sub plots received two zinc levels i. e. 0 .and 24 kg ZnSo J fed .= nursery. In the second part the first main plots were randomly assigned to two nitrogen sources i. e. urea and ammonium sulphate, while the second main plots received two time of nitrogen application i. e. total nitrogen on dry soil before transplanting and 213 of nitrogen on dry soil + 113 at panicle initiation. The sub plots received two zinc levels i. e. 0 and 24 kg ZnSo J fed . nursery. Central 10.5 m2 from each plot was harvested for yield determination. Yield and its components, chemical composition, -1 32- grain quality and other parameters were recorded. The results obtained could be summatized as followes :- I- Effect of nitrogen and zinc application on growth and yield of three rice varieties. 1- Flag leaf area: Over both seasons, Giza 177 gave the smallest flag leaf area compared with other two varieties. Increasing nitrogen rate fiom 40 to 60 kg N.1 fed. increased sic&cantly flag leaf area of rice plant in both seasons. Application of 24 kg ZnSoJkd . nursery had no siguficant effect on flag leaf area of rice in both seasons. the interactions between varieties and nitrogen rates, and between varieties and zinc were highly sigd3cant in the two seasons, whde the interaction between varieties, nitrogen levels and application of zinc was ~i~nificainn tt he first season only. 2- Plant height at harvest: Over both seasons, Giza 176 gave the tallest plants compared with other two varieties whil Giza 177 gaye the shortest ones. Increasing &trogen rates fiom 40 up to 60 kg/ fed. increased si&cantly plant height at harvest in the hl-o seasons. Application of 21 kg ZnSo J fed. nursery increased signiiicantly plant height at han-est in the second season only. The interactions between the three factors under study were not significant in both seasons. 3- Number of panicles / m2 : GZ 1368 gave sigmficantly higher number of panicles / m2 compared with other two varieties, while Giza 177 gave the lowest number. Neither nitrogen level nor zinc application had sigdicant effect on number of patiiclesl m2 in the two seasons. The effect of interactions between the three factors in the first season and between varicties and zinc application in the second season on number of panicle /m2 were sigmficant . 4- Panicle length: Giza 176 recorded the highest panicle length followed by GZl368 and Giza 177 in descending order in both seasons. Application of 60 kg/ fed. increased significantly panicle length in the first season compard with 40 kg W fed. Application of Zn had no sigdicant effect on panicle len,gh in both seasons. The interactions between varieties and nitrogen levels in both seasons and between varieties and zinc application in the second season and between nitrogen levels and zinc application in the fist season had sigruficant effect on panicle length.