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Abstract SUMMARY The present investigation was carried out to study the effect of irri gat ion at different ava i1abl e soil mo isture stress, maize cultivars and foliar application of zinc sulphate on growth, yield and its components, chemical composition and the water relation of maize plants. Three field experiments were conducted at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate. Egypt in 1988, 1989 and 1990 seasons. The selected areas were studied to determine field capacity. wilting point, bulk density, mechanical and chemical analysis. The experimental design was split-split plot with four replications. The main plots were randomly assigned to three irrigation levels, the sub-plots to three maize cultivars and the sub-sub plots to the three zinc sulphate concentration. The area of each plot was 33.6 ~ (6 x 5.6 m) with a ridges which were 70 cm apart and 6 m length. The treatments were as follows: I. Irrigation treatments: 1. Irrigated when 40% of the avai lable soil moisture was depleted. 2. Irrigated when 60% of the available soil moisture was depleted. 3. Irrigated when 80% of the available soil moisture was depleted. II. Maize cultivars: 1 . G; za 2. 2. T.W.C.310. 3. Karnak. III. Zinc sulphate levels: 1 . 0.0% 2. 0.3%. 3. 0.6%. Maize plants were sprayed twice when aged 30 and 45 days at a rate of 400 liters solution/feddan. All cultural practices except factors under study were carried out as common practices in the area. To study the growth analysis, samples of maize plants were taken at random from the second and seventh rows at 60. 75 and 90 days from sowing. Yield and yield components were dete rmined from a central area of each plot, equa 1 1/300/feddan. Characters studied: I. Growth attributes: 1. Dry matter accumulation and distribution/plant. 2. Leaf area/plant (drrf)’ 3. Total chlorophyll and earotenoids. 5. Crop growth rate. 6. Relative growth rate. 7. Net assimilation rate. 8. Time of silking. 9. Plant height (em) at harvest. 10. Ear height (em) at harvest. 11. Stem diameter (em) at harvest. II. Yield and yield components: 1 . Percentage of plants carried more than one ear. 2. Percentage of infection with late wilt disease. 3. Ear length (em). 4. Ear diameter (em). 5. Ear wei ght (g). 6. Number of rows/ear. 7. Number of grains/row. 8. Grain yield/plant (g). 9. Weight of 100-grain (9)· 10. Grain yield (kg/feddan) adjusted to 15.5% moisture. 11. Straw yield (ton/feddan). III. Chemical composition: 1. Crude protein percentage. 2. Protein yield (kg/feddan). 3. Oil percentage. 4. Oil yield (kg/feddan). 5. Zinc content of ma,~e grains (ppm). IV. Soil-water relations: 1 • Water consumptive use. 2 . Water use and yield relationship. 3. Water uptake patterns of maize. 4. water use efficiency. 5. Crop coefficient (Kc). V. Simple phenotypic correlations: The important results of this study could be summarized as follows: I.. Growth. attri butes: . A. Effect of years: 1. All characters were significantly affected due to years except stem diameter. The average values of dry weight/plant, leaf area/plant and leaf area index in the three stages, carotenoi ds, time of s i1king and plant height were high values in the third season. 2. The high mean values for chlorophyll a, b, (a+b), crop growth rate, relative growth rate, net assimilation rate were detected in the first season. B. Effect of water stress: 1. The averaS6 values of dry weight/plant at 60, 75 and 90 days after sowing, the percentage of ears at 90 days from planting, leaf area/plant and leaf area index at 60, 75 and 90 days from sowi ng, ch 1or ophy 11 a. carotenoi ds I crop growth rate, net assimilation rate, plant height, ear height and stem diameter were significantly decreased by increasing available soil moisture depletion from 40% to 80% in the combined analysis of 1988, 1989 and 1990 seasons. 2. There was a significant delay of silking time by ;ncreasing the 50;1 moisture depletion. Earlier silking was observed when maize plants were i rrigated at 40% so; 1 moisture depletion. 3. The mean values of the percentage of leaves and stem at 60 days from sowing, the percentage of leaves, stem, ears and tassel at 75 days after planting, chlorophyll b , (a+b), the ratio of chlorophyll (a+b) to carotenoids and relative growth rate were not significantly affected by water deficit. C. Varietal differences: 1. T.W.C.310 cultivar surpassed significantly Giza 2 and Karnak cultivars in dry weight/plant at 60, 75 and 90 days from sowing, the percentage of stem at 75 and 90 days after sowi ng, 1eaf area/pl ant and 1eaf area index at 75 and 90 days after planting, crop growth rate, plant height, ear height and stem diameter in the combined a~3lysis over the three seasons. 2. Karnak cultivar gave the highest values for the percentage of leaves/plant at 75 and 90 days from sowing, chlorophyll (a) and number of days to 50% silking. 3. Giza 2 cultivar surpassed significantly the other cultivars in the percentage of ears and stem/plant at 75 and 90 days from sowing. 4. The differences between the three cultivars under study were not sign i f icant in 1eaf area/p 1ant and 1eaf area index at 60 days from sowing, chlorophyll b, (a+bL carotenoids, the ratio of chlorophyll (a+b) to carotenoids, relative growth rate and net assimilation rate. D. Effect of zinc levels: 1. The average values of dry weight/plant at 60 and 75 days from sow; n9, the percentage of stem and 1eaves at 60 days from planting, the percentage of stem, ears, and tassel at 75 and 90 days after sowing time, leaf area/plant and leaf area index at 90 days after sowing, chlorophyll content, carotenoids, crop growth rate, relative growth rate, net assimilation rate, plant height and ear height were not significantly affected by zinc levels in the combined analysis over the three seasons. 2. The mean value of dry weight/plant at 90 days from sowing time, leaf area/plant and leaf area index at 60 and 75 days after sowing and stem diameter were significantly increased by incr-eas ing 1eve 1 of zinc su 1phate up to 0.3%. 3. Number of days to 50% s ilk in9 was sign if icant 1y decreased by application zinc sulphate as foliar up to 0.3%. E. Interaction effect: 1. The percentage of stem and ears at 90 days from sowing were highly significantly affected by the interaction between water stress and maize cultivars in the combined analysis over the three seasons. The highest percentage of 5tern was 40. 54% , obta ined from i rriga tion at 40% depletion in available water with T.W.C.310 cultivar, while the lowest one was 28.96%, obtained from watering at 60% soil moisture depletion with Giza 2 cultivar. The highest percentage of ears was (50.41 or 50. 11), obtained from watering at 40% or 60% depletion of soil moisture, respectively, with Giza 2 cu1tivar. whereas the other characters of growth anal ys is were not significant 1y affected by the interaction between water stress and maize cultivars. 2. The max imum mean va 1ues of the rat i0 of ch 1orophy 11 (a+b) to carotenoids was 1.80 mg/dm2 leaf area, obtained from 0.3% zinc sulphate and 40% depletion of soil moisture, whereas the lowest one was 1.69 mg/drrf 1eaf area, obtained from 40% soil moisture depletion and foliar application of zinc sulphate at 0.6%. However, no ” significant difference was obtained from the effect of the interaction between water stress and zinc level on the other growth characters. 3. There were sign ificant differences between the mean va 1ues of ch 1orophy 11 a, carotenoi ds and the ratio of chlorophyll (a+b) to carotenoids due to the interaction between maize cultivars and zinc levels in the combined analysis between the three seasons. T.W.c.3i0 cultivar with applied 0.3% zinc sulphate gave the highest value of chlorophyl 1 a and the ratio of ch 1orophyll (a+b) to carotenoids (2.39 and 1.82) mg/d~ leaf area, respective- 1y. The highest mean val ue of carotenoi ds was 2.37 mg/dnf leaf area. obtained from applied 0.3% zinc sulphate with Karnak cultivar. 4. The differences between the percentage of 1eaves and stem at 60 days from sowing a~d stem percentage at 75 days from sowing were significantly affected by the interaction between water stress, cult;vars and zinc levels in the combined analysis over the three seasons. The other characters of growth analysis were not significantly due to the interaction between water stress, maize cultivars and zinc levels. II. Yield and yield components: A. Effect of years: 1. All characters were differed significantly from year to another except ear length. 2. The high mean values were detected for ear diameter, ear weight, 100-grain weight, grain yield per plant and grain yield/feddan in the first season, and plants carry more than one ear percentage, late wilt disease percentage, number of grains/row and straw yield ton/feddan in the second season, number of rows/ear in the third season. B. Effect of water stress: 1. The effect of water stress treatments on the average values of plants carried more than one ear percentage, ear length, ear diameter, ear weight, number of rows/ear, number of grains/row, 100-grain weight and grain weight/plant were significant in the combined analysis over the three seasons. 2. Irrigation after 40% soil moisture depletion gave the highest value of plants carried more than one ear % (5.22%), ear length (20.94 cm), ear diameter (5.03 em), ear wei ght (304.94 g), number of rows/ear (13.80). number of grains/row (44.70), 100-grain weight (41.27 g) and grain yield/plant (191 .30g). 3. The average values of grain and straw yield/feddan were significantly decreased by increasing available soil moisture depletion up to 80% in 1988, 1989 and 1990 seasons as well as the combined analysis over the three seasons. The highest decreas~ in the percentage of grain yield/feddan was 26.41~, obtained from irrigation at 80% soil moisture depletion when compared with 40% depletion of available soil moisture in the combined analysis. 3. On the other hand, the percentage of late wilt disease significantly increased by increasing soil moisture depletion up to 80%. c. Varietal differences: 1. The percentage of plants carried more than one ear, late wilt disease %, ear length, ear diameter, ear weight, number of rows/ear, number of grains/row, grain yield/plant, grain yield and straw yield per feddan were significantly affected by maize cultivars in the combined analysis over the three seasons. 2. T.W.C.310 cultivar gave the highest values of the percentage of plants carried more than one ear (6.65%), ear length (22.34 cm), ear weight (313.27 g), number of grains/row (48.59), 100-grain weight (41.67 g). grain yield/plant (191.51 g), grain yield feddan (3792 kg) and straw yield/feddan (6.83 ton).3. Giza 2 cultivar gave the highest percentage of infection with late wilt disease. whereas T.W.C.310 cultivar gave the lowest percentage of infection with late wilt disease. 4. Karnak cultivar gave the maximum values of ear diameter (5.15 em) and number of rows/ear (14.59). 5. The differences between Giza 2 and Karnak cultivars were not signi f -j cant in number of gra insf row. grain yield/plant and per feddan. D. Effect of zinc levels: 1 . The differences between the mean values of plants ear r i ed more than one ear%, ear diameter, number of rows/ear and number of grains/row were not significant due to zinc levels in the combined analysis over the three seasons. 2. The mean values of ear length. ear weight, 100-grain weight, grain yield/plant, grain yield/feddan and straw yield/feddan were significantly increased by increasing foliar application of zinc sulphate up to 0.3%. 3. However, no significant difference was obtained by application zinc levels at 0.3% and 0.6% on the mean values of 100-grain weight, grain yield/plant and straw yield/feddan. 4. The average values of infection with late wi lt disease percentage 5igni fi cant 1y increased by ;ncreas in9 1eve 1 of zinc sulphate as foliar up to 0.6%. E. Interaction effects: 1. Insignificant effect of water stress and maize cultivars interact ion and water stress and zinc 1eve 1s ; nteract ion, were obtained for yield and yield components. 2. The average values of 100-grain weight, grain yield/plant and gra in y ie 1d/feddan were sign if icant 1y affected by the interact ion between cul t ivars and zinc 1eve 1s 1n the comb ined anal ys is over the three seasons. The highest mean values of 100-grain weight, grain yield/plant and per feddan were 42.46, 195.25 g and 3867 kg, respectively, obtained from T.W.C.310 cultivar with applied 0.6% zinc sulphate as foliar application. 3. There was a significant difference between the average values for number of grains/row due to the interaction between water stress, maize cultivars and zinc sulphate. The highest value for number of grains/row of T.W.C.310 cultivar was 49.63, obtained from irrigation after 40% soil moisture depletion with zinc sulphate at 0.6%. While the lowest one was 39.75, obtained from 80% depletion of soil moisture and zero sulphate with Karnak cultivar. III. Chemical composition: A. Effect of water stress: 1. The mean values of protein percentage was increased by increasing depletion of soil moisture from 40% to 80 minimum one was 129.33 kg, obtained from irrigation at 80% soil moisture depletion with Karnak cultivar. 2. The highest mean value of protein and oil yield were 342 kg and 225.83 kg/feddan, respectively, obtained from irrigation at 40% soil moisture depletion and applied 0.3% zinc sulphate as foliar. whereas the lowest ones were 254 kg and 131.17 kg/feddan. respectively, gained_ from irrigation at 80% depletion in available water without application of zinc sulphate. 3. The average values of protein and oil yield/feddan were significantly affected by the interaction between maize cultivars and zinc levels. Karnak and T.W.C.310 cultivars with applied 0.3% zinc sulphate as foliar gave the highest mean values of protei nand oi 1 yie 1d/feddan, respectively. 4. The interaction between irrigation after 40% depletion in available water with T.W.C.310 cultivar and applied 0.6% zinc sUlphate as foliar gave the highest mean values of protein and oil yield/feddan. 5. Insignificant effect of interaction between water stress and cultivars was obtained for protein yield per feddan. IV. Soil-water relations: 1. Seasonal consumptive use amounts increased as the availability of soil moisture increased in the root zone. The highest value of consumptive use was 64.43 em when plants were irrigated at 40% depletion in available water, while the lowest one was 49.12 cm when watering at 80% soil moisture depletion. Maize cultivars and zinc applied had no obvious effect on water consumptive use. 2. The highest value of seasonal consumptive use rate was 0.53 em/day accompanied by irrigation at 40% depletion in available water. Whil~ the lower value was 0.41 em/day related to irrigation at 80% depletion of soil moisture. The daily consumptive use increased gradually as plant growth increased and reached its maximum at about silking and seed formation. Monthly consumptive use reached its maximum values during August which represent the period of maximum demand for water by maize. 3. The relation between consumptive use in cm eX) and maize grain yield in kg/feddan (Y) for all moisture treatments was linear and could be described by the following linear equation: y = -420.68 + 65.24 X The grain yield of mai ze increased 65.24 kg/feddan by increasing one unit (em) of seasonal consumptive use of maize. 4. The correlation coefficient for the two variables was significant positive and equal 0.999. 5. Maize plants extracted about 83.33% and 16.67% of its water needs from the upper and the second foot, respectively, when maize plants were irrigated at 40% depletion in available water. Increasing the soil moisture stress, i.e.t 80% soil moisture depletion resulted in increasing the percentage of moisture extracted by maize roots from the second foot (26.44%). 6. The highest water use efficiency value was 1 .40 kg/m3 of water consumed recorded when maize plants were irrigated at 40% depletion in available water. whereas the lowest one was 1.35 kg/m3 produced from wateri ng at 80% soi 1 moisture depletion. T.W.C.310 cultivar utilized water more efficiency than the other cultivars. Applying zinc sulphate at 0.3% resulted in producing the highest water use efficiency than the other concentration. 7. Potentia 1 evapotransp irat ion was estimated by methods namely modified Penman. Radiation. modified Blaney- Criddle and the class A pan. Values of potential evapotranspi rat ion obta ined by the 1ast two methods were lower than those obtained from Penman and Radiation methods. 8. The crop coefficient (Kc) of maize was estimated by the previous methods. It was low at the beginning of the growing season. the increased as a result of the increase in crop cover. At the end of the season. a reduction in evapotranspiration rates was noticed as the plants were going to maturity. Crop coefficient (Kc) values calculated by using modified Slaney Criddle and the class A pan methods were hi ghe r than that obta ined by mod if ied Penman and Radiation methods. It could be concluded that the calculated value of 0.88 for (Kc) could be used in calculating the consumptive use of maize in North Delta area as estimated by the aid of Penman or Radiation methods. v. Simple phenotypic correlations: 1. Significant positive correlation values were detected between grain yield/feddan and each of straw yielq (t/feddan), grain yield/plant, the percentage of plants carried over one ear, i0C-grain weight, ear length, ear weight, number of grains/row, plant height, ear height, stem diameter and dry matter/plant, leaf area/plant and leaf area index at 75 days from sowing, crop growth rate, relative growth rate and net assimilation rate. 2. Insignificant positive correlation coefficients were detected between grain yield/feddan and chlorophyll a, b , (a+b) and carotenoids. 3. Insignificant negative correlation value was found between grain yield/feddan and days to 50% silking. 4. Significant negative correlation value was found between grain y;eld/feddan and late wilt disease percentage. It could be recommended from this work that the best water level for irrigating maize plants when 40% ASt-il.) is der1eted, applying zinc sulphate as foliar at a rate of 0.3% W” ;.C.310 cultivar produced higher grain yield/feddan. |