STUDIES ON FERTILIZATION AND IRRIGATION OF CITRUS CROP IN DESERT REGIONS AND INFLUENCED BY CLIMATIC CONDITIONS

Abstract

The present study was conducted during 2013 and 2014 seasons on Balady mandarin trees in a private farm at Waddi – Elnatron region , Behira Governorate . The trees was 10- year old and planted at 5 X 5 m2 apart (168 tree/ fed ) under drip irrigation system . uniform in size and in on –year at first season of study . All horticultural practices including , pest management fertilization with micro elements were done . A split plot design in 3 replicate was followed as experimental design where irrigation levels put in main plots and NPK fertilization level arranged in sub – main plot . The season of experiment in first year begin from Nov . 2012 till Nov 2013 and second year begin from Nov. 2013 till Nov. 2014 . Tow factors was evaluated in this experiment :- 1. NPK levels Three levels of NPK fertilization levels was evaluated followed the equation of N1 , P0.5 , K 1 :-  F1 : N70 : P35 : K 70  F2 : N90 : P45 : K 90  F3 : N110 : P55 : K 110 Nitrogen was added as ammonium nitrate (33.5%) , phosphors was added as monoammonium phosphate MAP (N12 P 61 K 0) and K added as solo – potash (50% K2O). The amount of NPK fertilizers were added as drip irrigation system with the two levels under study . 2. Irrigation levels 4000 and 5000 m3 of irrigation water were applied to fedd expressed as 24 and 30 m3 / tree/ year presented as 168 tree /fed The amount of irrigation water was applied via drip irrigation system during 12 months begin from Nov. till following Nov divided according to physiological stage of Balady mandarin trees 2 irrigation level x 3 NPK levels x 3 replicate (2 tree each replicate) = 36 trees for each season The following parameters were measured during the two growth seasons to evaluate the effect of studied treatments on growth nutrient status , yield and fruit quality of Balady mandarin 1. Vegetables growth parameters 1.1- Average spring shoot length (cm) 1. Balady mandarin trees irrigated with 5000 m3/fed per year (30 m3/tree represented as 165 tree/fed.) produced higher spring shoots length than the trees irrigated with 4000 m3/fed. Per year (24 m3/tree) with significant differences between them in first season only 2. The trees fertilized with NPK at 110-55-110 units was superior than the trees fertilized with 70-35-70 or 90-45-90 units in producing higher spring shoot length with significant differences between them in both studied seasons. 3. The highest interaction value of spacing shoot length in first season was obtained with high irrigation level (5000 m3/fed.) and high NPK level (110-55-110 units). On the other hand, the shortest spring shoot was obtained from low irrigation level and low fertilization rate. 1.2- Av. Leaf area (cm2) 1. It is clear that both water irrigation quantities and NPK fertilization levels greatly affected average leaf area of Balady mandarin trees 2. The trees irrigated with 30 cm3/tree/year (5000 m3/fed.) released leaves with high areas than those irrigated with 24 m3/tree/year (4000 m3/fed.) in both seasons with significant differences between them. Application of high NPK levels (110-55-10 units) produced highest values of leaf area than other NPK levels in both seasons. No significant differences were detected between highest medium levels of NPK in first season. 3. Highest values of interaction between the two studied factors in both seasons were obtained with high irrigation level (30 m3/ tree) at high NPK level (110-55-110 absolute level). On the other hand, the least interaction values for both seasons were obtained with low irrigation levels (24 m3/tree) at low fertilization level (70-35-70 units). 1.3- Average number of leaves / shoot 1. As it previously mentioned in shoot length and leaf area characters, a great effect to high levels of irrigation water (5000 m3/fed) on number of leaves per shoot was also found. Significant differences between the two used levels of irrigation water on number of leaves were recorded in both seasons. 2. An evident increase in number of leaves were obtained with high NPK fertilization level (110-55-110 units) with significant differences between the three levels of NPK levels in both studied seasons. 3. Interaction between the two studied factors was significant in most cases, high interaction value of number of leaves in first and second season were recorded by high irrigation level (5000 m3/fed.) and high NPK level (110-55-110 units). The least interaction values of number of leaves were released from low irrigation level and low NPK fertilization rate.

1.4- Shoot thickness (cm) 1. High shoot thickness values produced from high irrigation level (30 m3/tree = 5000 m3/fed.) 2. High and medium NPK levels (110-55-110 and 90-45-90 units) were similar in their effect on shoot thickness during the two studied seasons. Least values of shoot thickness were recorded by low NPK level (70-35-70 units) in both seasons. 3. Interaction between the two studied factors was significant in both seasons, the high interaction shoot thickness values were detected from high irrigation level (30 m3/tree/ year= 3000 m3fed./fed/year) and high NPK/level (110-55-110 units). The least interaction shoot thickness values were recorded by low irrigation level (24 m3/ tree= 4000 m3/fed.) and low NPK fertilization rate (70-35-70 units). 2- Chemical constituents 2.1- Leaf nitrogen % (N%) 1. No significant differences between the two irrigation levels on leaf N% during the two studied seasons 2. A great effect to NPK fertilization levels on leaf N% in both seasons were obtained with significant differences between them. As the NPK fertilization levels were increased the leaf N% was increased, where the high leaf N% for both season were obtained with 110-55-110 units. 3. Interaction values were significant in most cases high interaction values of leaf N% was recorded by low irrigation level (4000 m3/fed.) and high NPK fertilization level. On contrary, the least interaction value was recorded by low irrigation level and low NPK fertilization level.