Effect of Spatial Distribution of Plants Under Different Watering Regimes on the Yield and its Components of Corn (Zea mays, L.) تأثير التوزيع الفراغي للنباتات تحت نظم مختلفة من الري علي المحصول ومكوناته في الذرة الشامية Howida Ezz El-Din Abd El-Kader هويدة عزالدين عبدالقادر Ragab Ahmad Dawood, Anaam Hlame Galal إنعام حلمى جالل،رجب أحمد داوود Abstract: Two field experiments were carried out during to summer seasons (2007 and 2008) at the Experimental Farm of the Faculty of Agriculture, Assiut University, Assiut, to study the response of maize yield and its components for three irrigates intervals (12, 18 and 24 days), (Single Cross Watania 4 and Three Way Cross 310) and four spatial distribution of plants (40x50 cm, 35x60 cm, 30-70 cm and 25x80 cm). Experimental design was split-split plot, where irrigation intervals were assigned to the main plots, genotypes were in the sub-plot and spatial distribution of plants were occupied the sub-sub-plots. The obtained results could be summarized as follow: A- Growth traits: 1- Plant height was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and plant distribution (30x70 cm) in both seasons. Concerning the first order interactions, the tallest plants were observed by irrigation interval at 12 day with the Single Cross Watania 4 or by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the second season only. As well as, the tallest plant was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the tallest plants were recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 2- First ear height was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and plant distribution (30x70 cm) in both seasons. Concerning the first order interactions, the maximum values for first ear height were observed by irrigation interval at 12 day with the Single Cross Watania 4 or by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the first season or in the second season only, respectively. As well as, the maximum value was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the maximum values for the first ear height was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. B – Yield and its components: 1- Ear length was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Except genotype was not significant in the first season. Concerning the first order, interactions the longest ear was observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the second season only. As well as, the longest ear was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the longest ear was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 2- Ear diameter was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the greatest ear diameter was observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the second season only. As well as, the greatest ear diameter was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the greatest ear diameter was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 3- Number of rows/ear was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum No. of rows/ ear was observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the first season only. As well as, the maximum No. of rows/ear was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the maximum number of rows/ear was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 4- Number of grains/row was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum No. of grains/row was observed by irrigation interval at 12 day with the Single Cross Watania 4 in the first season only. As well as, the maximum No. of grains/row was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the maximum number of grains/ear was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 5- 200-grain weight was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum values for 200-grain weight were observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the first season only. As well as the maximum values were recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) or by irrigation interval at 12 day with Single Cross Watania 4 in both seasons. As for the second order interaction, the maximum values for 200 grain weight were recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 6- Shelling percentage was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum value for shelling percentage was observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the first season only. As well as, the maximum value was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) or by irrigation interval at 12 days with Singld Cross Watania 4 in both seasons. As for the second order interaction, the maximum values for shelling percentage were recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. 7- Grain yield/fed. was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum values for grain yield were observed by irrigation interval at 12 day with the Single Cross Watania 4 or by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 and irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the maximum values for grain yield were recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season. C – Grain quality 1- Crude protein % was reacted significantly to the three main effects i.e. irrigation, genotype and the spatial distribution of plants in favour of irrigation interval at 12 day, or Single Cross Watania 4 and (30x70 cm) in both seasons. Concerning the first order interactions, the maximum value for crude protein % was observed by spatial distribution of plants (30x70 cm) with the Single Cross Watania 4 in the first season only. As well as, the maximum value was recorded by irrigation interval at 12 days with spatial distribution of plants (30x70 cm) in both seasons. As for the second order interaction, the maximum value for crude protein % was recorded by irrigation interval at 12 day with Single Cross Watania 4 under spatial distribution of plants (30x70 cm) in the second season.