الفهرس 
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Abstract
The present study was carried out at the Agricultural Experimental Research Station, Faculty of Agriculture, Alexandria University during the two summer seasons of 2018 and 2019.
The objectives were to:
1. Evaluate the relative efficiency of non-replicated and replicated designs in detecting the importance of studied factors (sowing date, plant density and phosphorus fertilization), and their interactions, that affect growth, grain yield and yield attributes of maize cultivar Giza 168.
2. Determination of response of maize to sowing date, plant density and phosphorus fertilization levels.
3. Study the allocation of phosphorus to different plant organs (roots, stems, leaves, cobs and ear sheath and grains) at different stages of growth (40, 80 DAS and 105 DAS). To realize the objectives of the study, seven experimental designs, divided in two groups, i.e., replicated designs with three replications [Randomized complete block (RCBD), Split plot design (SPD), Split split-plot design (SSPD) and Three-dimensional lattice design (3-DLD)]; and non-replicated designs [One-rep designs (without and with center points), Rotatable Central Composite Design (RCCD) and Partially Replicated Central Composite Designs (PRCCD)]. In addition, the RCCD was applied to determine the effect of sowing date, plant density and phosphorus fertilization levels on maize growth and productivity, in addition to phosphorus concentration in different plant parts at three sampling dates (40, 80 and 105 DAS) to determine P use efficiency. Parameters used for comparison of experimental designs efficiency included, Mean Square Error (MSE), Coefficient of variation (C.V.%), Coefficient of Determination (R2) from regression analysis and Relative Efficiency (R.E.). Measured characters: I- Vegetative characters That group included two characters, i.e., plant height and ear leaf area. II- Yield and yield attributes That group included four characters, i.e., average grain weight/ ear, 100-grain weight, biological yield and grain yield.
The results of the present investigation could be summarized as follows:
I- Comparison of Experimental Designs Efficiency:
1. For the vegetative characters, the RCBD design and error “a” of SPD and SSPD designs gave the highest MSE (419.60, 581.04 and 454.76), respectively, for plant height, while the ear leaf area had the highest MSE values in the 3-DLD and RCBD (7758.79 and 1389.51), respectively. 112
2. The highest value of C.V.% for plant height was estimated for RCBD (7.42), while, the lowest value of C.V.% was in the SSPD design in error “c” (3.05). For ear leaf area, the 3-DLD gave the highest C.V. (10.67), while the lowest value was estimated for error “c” in SSPD (2.02).
3. All designs gave a high R.E. for plant height and leaf area, except the 3-DLD design which exhibited a very low efficiency in ear leaf area (0.18), while the SSPD design at error “c” was of the highest efficiency (11.85).
4. The R2 was high in the SPD, SSPD and 3-DLD designs, while it was low in the RCBD design for plant height (0.48), while R2 values for all designs was high.
5. The MSE for the 3-DLD, value was high for average grain weight/ ear and 100-grain weight compared to the RCBD design. Also, it was lower in R.E. for those characters (0.91 and 0.43), respectively.
6. The value of MSE for biological yield in the SPD at errors “a and b” were high (33.66 and 13.48, respectively) compared to the RCBD while SSPD gave lower MSE at “b” and “c” errors compared for RCBD (0.44 and 0.27), respectively.
7. The results showed that the value of R2 was relatively high (0.74) in yield and yield attributes, except 100-grain weight (0.59).
8. For non-replicated designs, the results showed that the value of both MSE and C.V.% was higher in the one-rep without center points design compared to all designs in that group.
9. The RCCD design gave the highest R.E for all measured characters compared to the one-rep without center points design.
10. The results showed that the PRCCD-F design was more efficient than the PRCCDFS and PRCCD-S designs for biological yield (5.68) and grain yield (2.04).
II: Effect of sowing date, plant density and phosphorus fertilization on maize growth and productivity:
1- The analysis of variance and regression coefficients showed that plant height was significantly and positively affected by the quadratic components of SD (9.97*), PD (11.74*) and linear component of P (10.90*) with R2 = 0.79. The coefficient of variation for plant height was 4.9%. The lowest optimal of SD and PD was May 15th and 23355 plants/ ha.
2- Analysis of variance and regression coefficients showed that the ELA was significantly and positively affected by quadratic components of SD (50.11*), PD (25.84*) and P (21.03*). The linear interactions between (SD*P) and (PD*P) were of significant and negative effects (-30.61* and -22.54*, respectively) with R2 = 0.78 and CV was 2.38 %.
3- Analysis of variance and regression coefficients indicated that the average grain weight/ ear was significantly and negatively affected by the linear components of SD and PD (-30.30* and -24.33*, respectively) and quadratic component of PD (-15.47*) with R2 = 0.88. The coefficient of variation for average grain weight was 4.62%.