Response Of Olive Trees To Fertilition Under Rainfed Conditions:

Ahmed Emad Mahrous Abd El- Rhman

This study was conducted during three successive seasons of 1999,2000 and 2001 at Raas El-Hekma area, Matroh Governorate as a trial to study the effect of different nitrogen sources i.e slow release and fast release nitrogen fertilizers on growth, leaf mineral content, fruiting and fruit quality of olive trees cv. Manzanillo.Thirty—year—old olive trees, nearly similar in growth vigour, healthy, planted at 7 x 7 m. apart and received regularly the recommended horticultural practices were devoted for this study. The rainfall in the experimental region recorded 92.0, 115.0 and 85.6 mm in 1999, 2000 and 2001, respectively according to Matroh Resource Manegment Project (Adaptive Research Center).Moreover,the following treatments were assigned for application on the selected trees under investigation according to their expected blooming condition in the following season ( ”On” or ”Off” years ). The trees were in the ”On” year and were going to an expected ”Off” year. In other words, some of the tested treatments were applied during an expected ”Of’ year (1999&2001) and the others were applied during an expected ”On” year (2000).The trees were subjected to one of the following fertilizer treatments:1-Trees were fertilized with 200 and 300 g actual nitrogen/tree/year ammonium nitrate (NH4NO3 — 33.5%N) as fast release N fertilizer source in mid-February and mid-May (1999&2001) during an’ • •’ ’ ”1285-SUMMARY AND CONCLUSION4 A 4’ * A x.1’ A 41 ,• * 41 A A A AA A 41 A 1 ”1 Ak A A. A * A A A * A A A.* * A A Akexpected ”Off” years and supplemented with 400 and 600 g actual nitrogen/tree/year in the form of ammonium nitrate in mid-February and mid-May (2000) during an expected ”On” year.2-Trees were fertilized with 200 and 300 g actual nitrogen / tree / year ammonium sulphate ((NH4) 2SO4 — 20.5%N) as fast release N fertilizer source in mid-February and mid-May (1999&2001) during an expected ”Off” years and supplemented with 400 and 600 g actual nitrogen / tree / year in the form of ammonium sulphate in mid-February and mid-May (2000) during an expected ”On” year.3-Trees were fertilized with 200 and 300 g actual nitrogen / tree / year urea((NH2 —CO- NH2 — 46%N) as fast release N fertilizer source in mid-February and mid-May (1999 & 2001) during an expected ”Off” years and supplemented with 400 and 600 g actual nitrogen / tree / year in the form of urea in mid-February and mid-May (2000) during an expected ”On” year.4-Trees were fertilized with 200 and 300 g actual nitrogen/tree/year in the form of phosphorus coated urea (PCU 37% N) as slow release fertilizer in mid-February (1999 & 2001) during an expected ”Off” years (1999 & 2001) and fertilized with 400 and 600 g actual nitrogen / tree / year in mid-February (2000) during an expected ”On” year.5-Trees were fertilized with 200 and 300 g actual nitrogen / tree / year in the form of formaldehyde coated urea (UF 37% N) as slow release fertilizer in mid-February (1999 & 2001) during an expected ”Off” years (1999 & 2001) and fertilized with 400 and 6001295-SUMMARY AND CONCLUSIONg actual nitrogen tree / year in mid-February (2000) during anexpected ”On” year.6-Trees were fertilized with 200 and 300 g actual nitrogen / tree / year in the form of Bentonite coated urea (BCU 37% N) as slow release fertilizer in mid-February (1999 & 2001) during an expected ”Off” years (1999 & 2001) and fertilized with 400 and 600 g actual nitrogen / tree / year in mid-February (2000) during an expected ”On” year.Generally, this investigation included two experiments ”Off” year fertilizer treatments and ”On” year fertilizer treatments. Each experiments is a factorial experiment (2 N fertilizer sources (fast & slow) x3 N forms [(ammonium nitrate, ammonium sulphate and urea) and (phosphorus coated urea, formaldehyde coated urea and bentonite coated urea)].The tested treatments of each experiment (On & Off years) were arranged in a completely randomized block design with four replicates for each treatment and each replicate was represented byone tree.The obtained results could be summarized as follow:.. ..1305-SUMMARY AND CONCLUSION4.§.-t•JP A *AA A ..0-k•A A *AA .§,..t..A4 *AA A A A 4,[Experiment IEffect of nitrogen fertilizer source and rate on tree growth, leaf nutrient content, fruiting and fruit quality of Manzanillo olive trees duringOff” years.5.1.1. Tree growthGenerally, slow release N. fertilized trees produced longer shoots, higher number of leaves per shoot, larger leaf surface area, leaves richer in their chlorophyll (a&b) content and heavier leaf dry weight than the analogous ones fertilized with fast release N. fertilizers. Besides, the studied vegetative growth parameters responded significantly to the increase in nitrogen fertilizer rate, hence the higher N. fertilizer rate (300g N/tree/year) recorded the highest values of the previously mentioned vegetative growth parameters than did the lower nitrogen fertilizer rate (200g N/tree/year). Furthermore, the tested forms of slow release nitrogen fertilizers (PCU, UF and BCU) surpassed the tested forms of fast release N. fertilizers (ammonium sulphate, ammonium nitrate and urea) in exerting higher positive effect on the studied vegetative growth parameters. Briefly, PCU proved to be the superior slow release N. fertilizer form, followed descendingly by UF and BCU. On the contrary, urea showed to be the least efficient fast release N.A -,k,AA1315-SUMMARY AND CONCLUSION• - : : , ’ • ;. •fertilizer form in this respect. On the other hand leaf shape index showed meaningless response to nitrogen fertilizer source, form andrate as well as their interactions.5.1.2. Leaf mineral contentGenerally, leaves of slow release N. fertilized trees had higher values of nitrogen, phosphorus, potasium, calcium, mangnesium, zinc, iron, manganese and cupper than those of fast release N. fertilized ones. Besides, increasing nitrogen fertilizer rate enhanced the previously mentioned leaf mineral content. Furthermore, the tested forms of slow release N. fertilizers particularly PCU followed by UF and finally BCU exerted higher positive on the aforementioned leaf mineral content than did the tested forms of fast release N. fertilizer forms (ammonium sulphate, ammonium nitrate and urea). On the centrary, urea form induced the least positiveeffect in this concern.5.1.3. Tree bloomingIn summary, slow release N. fertilized trees produced higher number of inflorescences per meter, higher number of flowers per inflorescence and higher perfedt flowers percentage than the analogous ones fertilized with fast release N. fertilizers. Besides, the studied blooming parameters responded significantly to the increase in nitrogen fertilizer rate, hence the higher N. fertilizer rate (300g N/tree/year) recorded the highest values of the previously mentioned blooming parameters than did the lower nitrogen fertilizer rate (200g N/tree/year). Furthermore, the tested forms of slow release nitrogen fertilizers (PCU, UF and BCU) surpassed the tested forms1325—SUMMARY AND CONCLUSIONss,.