PHYSIOLOGICAL STUDIES ON SOME CITRUS TREES By AMIRA FAHMY ABD EL-AZIZ EL-WAKIL B. Sc. Agric. Sci. (Horticulture), Fac. Agric., Cairo Univ., 1996 M. Sc. Agric. Sci. (Plant Physiology), Fac. Agric., Cairo Univ., 2008 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY In Agricultural Sciences (Plant Physiology) Department of Agricultural Botany (Plant Physiology) Faculty of Agriculture Cairo University EGYPT 2017 SUPERVISION SHEET PHYSIOLOGICAL STUDIES ON SOME CITRUS TREES Ph.D. Thesis In Agricultural Sci. (Plant Physiology) By AMIRA FAHMY ABD EL-AZIZ EL-WAKIL B.Sc. Agric. Sci. (Horticulture), Fac. Agric., Cairo Univ., 1996 M.Sc. Agric. Sci. (Plant Physiology), Fac. Agric., Cairo Univ., 2008 SUPERVISION COMMITTEE Dr. AHMED HUSSEIN HANAFY AHMED Professor of Plant Physiology, Fac. Agric., Cairo University Dr. MOHAMED RAMADAN ABOU-ELLA NESIEM Professor of Plant Physiology, Fac. Agric., Cairo University Dr. HESHAM ALI ALLAM Head Research of Fruit Handling Department, Horticulture Research Institute, Agricultural Research Center, Giza Name of Candidate: Amira Fahmy Abd El-Aziz El-Wakil Degree: Ph.D. Title of Thesis: Physiological studies on some Citrus trees Supervisors: Dr. Ahmed Hussein Hanafy Ahmed Dr. Mohamed Ramadan Abou-Ella Nesiem Dr. Hesham Ali Allam Department: Agricultural Botany Branch: Plant Physiology Section Approval: / / 2017 ABSTRACT The present study was carried out during two successive seasons of 2011/2012 and 2012/2013 to study the effect of GA (20 and 30 3 ppm), some micronutrients, i.e. boric acid (100 and 200 ppm) chelated zinc (62.5 and 125 ppm) and K-silicate (100 and 200 ppm)as well as chitosan (250 and 500 ppm) foliar applications on growth, fruit yield and fruit quality as well as leaves and fruit chemical compositions of “Washington” navel orange trees grown at two different location i.e., El-Qalubia and El-Monufia Governorates, Egypt. After harvest, fruits were stored at 2°C and R.H. 85-90% for 45 days. The results indicated that GA , K-silicate and chitosan foliar 3 application treatments recorded a significant increase in some vegetative growth, fruit set %, yield as well as fruit physical and chemical characteristics, i.e. weight loss, firmness, color and juice %. In addition, chemical composition of leaves, i.e. total sugars, total free amino acids, total soluble phenols, total pectin and plant hormone as well as chemical composition of fruits, i.e. T.S.S.%, acidity, ascorbic acid, total sugars, total free amino acids, total soluble phenols and mineral nutrients of leaves and fruits, i.e. N, P, K, Ca, B, Zn and Si concentrations. Generally, the results revealed that trees showed a significant increase in all most previous characteristics with treated by GA , K- 3 silicate and chitosan foliar applications improved most of the studied in fruit quality and reduced fruit weight loss during cold storage at 2°C. Key words: chitosan, GA , boric acid, chelated zinc, K-silicate, 3 “Washington” navel orange, fruit quality, yield, pectin, growth characters. تفسهفنا ِارٕخكد :حجرذلا ميكٕنا شيشؼنا ذبػ يًٓف ةزييأ :ةلاطلا نسا حنإًنا راجشأ ضؼب يهػ تيجٕنٕيسف ثاسارد :حلاسرلا ىاونع ذًحأ يفُح ٍيسح ذًحأ : روتكذلا : ىوفرشولا ىيسَ لاؼنا ٕبأ ٌاضير ذًحي : روتكذلا ولاػ ٗهػ واشْ : روتكذلا ٧١٠٢/ / :حجرذلا حنه خيرات ثابُنا ايجٕنٕيسف :عرف يػارشنا ثابُنا :نسق يترعلا صلختسولا ررجةشأ ًةلع )م٣١٢٤ – ٣١٢٣ م )م٣١٢٣ –٣١٢٢ ٌسةسمسلا ا ةلا ةساردلا هذه تٌرجا درةسب ررجةشةا ةلسرلاس مةت مةٌح درةيحلا اةبل رةس ت سرةلاسرٌمرت ةساردل لةلذ م رةس مبا ارقتربلا م ) مةٌلسلا ىةف ءزةج ٠٢٢ م ٠٢٢ لٌرمبلا ضسرح م ) مٌلسلا ىف ءزج ٠٢ م ٠٢ ٌلاربجلا ٠٢٢ م ٠٢٢ ممٌةةسرتمبلا تراٌلٌةةس درةةسب م ) مةةٌلسلا ىةةف ءزةةج٠٠٦ م ٧٠٢٦ ىةةبللاسلا لةةنزلا دةةح ىةةلع اةةا ادرةةكس ) مةةٌلسلا ىةةف ءزةةج ٦٢٢ م ٠٦٢ ازمتٌةةشلاا درةةس م ) مةةٌلسلا ىةةف ءزةةج ررةسملا دمةج م ىرسملا اميحسلا م مسنلا ىلع ( لسرلاس رٌغلا) امرتنالا لسرلاس ررجشة فرضلارب ٌتكلتلاس ٌتعرزس ىف ٌسرنلا رس مبأ فني ارقتربلا ررسمل للذا م قارملأل ىمرسٌالا بٌارتلا م ةلسرلاسلا ررةسملا ٌزةلات مةت درةيحلا دةلابم . ٌفمنسلا ظفرحسب ىرلاةام ٌبمٌلقلا ظفرحسب رسهادحا . ممٌ ٥٦ دسل % ٠٢ – ٥٦ حمارتت ٌبسن بمطر فمرظ تحت م م°٠ رارح جرد ًلع ازمتٌشلا مأ ممٌسرتمبلا تراٌلٌس مأ ٌلاربجلا درسب لسرلاسلا ررجشةا ا جئرتنلا ترهظأ دقل م فرةضةرب اميحسلا م دقلالا بسن م ىرضلالا مسنلا تركي ضلاب ىف ٌمنلاسلا درٌزلا ىلا تدأ دل م )رٌةيلالا بةسن م ٌمةلتلا ةجرد م ب ةيلا م زملرب دقكلا ررسملل ٌجملمٌسكلا تارٌغتلا ضلابل ترٌراةسلا امس قارملأل ٌمضلالا ترنماسلل يمرسٌالا بٌارتلا ًف تارٌغتلا ضلاب ىلا تدأ للذا ترةنمسرهلا م ىةلالا ٌةتابلا م ةٌلالا ةبئاذلا تلامةنٌكلا م ٌلالا رحلا ٌنٌسةا ضرسحةا م ٌلالا ىةةلا تدأ للذةةام )لٌتٌةةسا امدةةنةا ضسرةةح – لٌةةسٌسبةا ضسرةةح – لةةللٌربجلا ضسرةةح ةةٌتربنلا م ٌلالا بئاذلا بليلا دامسلا امس ررسملل ٌمضلالا ترنماسلل يمرسٌالا بٌارتلا ًف تارٌغتلا ضلاب تلامةنٌكلا م ٌلالا رحلا ٌنٌسةا ضرسحةا م ٌلالا ترٌراسلا م لٌبرماسلاا ضسح م ضمسحلا رمكةةسمكلا م ٌجمرةةتٌنلا رةةينع اةةمس ررةةسملا م قارملأةةل ةةٌندلاسلا رةةيرنلالا رةةضٌأ م ةةٌلالا ةةبئاذلا . ماٌلٌسلا م مرمبلا م لنزلا م ممٌسلرالا م ممٌسرتمبلام ازمتٌةشلا مأ ممٌةسرتمبلا تراٌلٌس مأ ٌلاربجلا درسب لسرلاسلا ررجشةا ا امقلا اسٌ رسمسعم دمةةجب ةةيرلالا جئرةةتنلا اةةضفا تةةطعا دةةل ممةةٌ ٥٦ دةةسل )م°٠ رارةةح ةةجرد ًةةلع ٌزةةلاتلا دةةلاب . سدلاتسسلا يرلالاا ت سرلاسلرب نررقسلرب ًلالا دقكلا س رادقس الأ م ررسملا ، ممٌسرتمبلا تراٌلٌس ، ىبللاسلا لنزلا ، لٌرمبلا ضسح ، ٌلاربجلا ، ازمتٌشلا : ةلادلا تاملكلا .مسنلا تركي ، ٌتابلا ، اميحسلا ، ررسملا دمج ، رس مبأ ارقترب حلاوولا راجشأ ضعت يلع حيجولويسف خاسارد يه حهذقه حلاسر ليكولا زيزعلا ذثع يوهف جريهأ ٠٩٩١ ، جرهاقلا حعهاج ، حعارزلا حيلك ، )ييتاست( حيعارزلا مولعلا سويرولاكت ٧١١٢ ، جرهاقلا حعهاج ، حعارزلا حيلك ، )خاثنلا ايجولويسف( حيعارزلا مولعلا ىف ريتسجاه تجرد ٗهػ لٕصحهن حفسلفلا هاروتكد يف حيعارزلا مولعلا )خاثنلا ايجولويسف( يعارزلا خاثنلا نـــــــسق خاثنلا ايجولويسف عرف حـــــعارزلا حــــــيلك جرهاــقلا حــعهاـج رـــــــــصه ٧١٠٢ INTRODUCTION In Egypt, horticultural commodities are a major supplier to the domestic market and account for a considerable amount of the total agriculture exports. Citrus fruits are the backbone of fruit crop yield and could be regulated as cash crop in Egypt. The total planted area of citrus species and cultivars increased in the last few years to reach about 160328 feddans, while the productive area is about 139757 feddans and producing nearly 1266249 tons*. The planted area of navel orange trees in El-Qalubia and El- Sadat are about 30748 and 18151 feddans, while the productive area are about 29818 and 18050 feddans which are producing about 322511 and 176529tons*, respectively and the total exporting orange fruits is about 877289tons,*(according to the latest statistics of Ministry of Agriculture and Land Reclamation, E.A.S., 2014). The Washington navel orange is the principal orange cultivar in Egypt and was recommended as a variety of storage temperatures for citrus fruits, but any recommendation is at best an approximation because storage is affected by multiple pre and post-harvest factors such as climate, cultural practices, time of harvest, postharvest handling and storage conditions (temperature, relative humidity and atmosphere composition). Productivity of citrus trees depends on many abiotic (climate, soil, nutrition and irrigation management) and biotic (rootstock, cultivar, insect pest and disease management) factors (Iglesias et al., 2007). * Ministry of Agriculture and Land Reclamation, Economic Affairs Sector, 2014. Climate changes may also change the types, frequencies, and intensities of various crop and pests; the availability and timing of irrigation water supplies; and the severity of soil erosion. Sandy soils are poor in low macro and micronutrients. Plant nutrient management could influence flowering, fruit set, fruit size, the amount of vegetative growth and other plant characteristics in most citrus fruit species. For example, foliar application of Zn can improve citrus fruit yield and quality and control the premature fruit drop (Ashraf et al., 2012). Different workers suggested that application of suitable combinations of plant growth regulators, macro and micronutrients can control the excessive fruit drop and improves the yield and quality of citrus fruits (Saleem et al., 2005). Therefore, effective supply of nutrients and plant growth regulators is necessary to produce high quality citrus fruits and control excessive citrus fruit drop which involves selection of appropriate combinations of nutrients and plant growth regulators, their rate, time and method of application. Application of plant growth regulators is effective in reducing the excessive premature fruit drop. The beneficial effects of spraying GA and nutrient elements to achieve high yield production with high 3 fruit quality of navel orange (Abd-Allah, 2006). The micro – nutrient boron plays as important role in growth behavior and productivity of trees. It increases pollen grains germination and pollen tube elongation, consequently fruit set percentage and finally the yield (Garcia – Papi and Garcia – Martinez, 2003). Silicon is a beneficial micronutrient, and deficiencies significantly affect some plant health. There are numerous studies on the use of silica amendments to control disease mechanically when applied as a foliar spray. Potassium silicate is a source of highly soluble potassium and silicon. It is used in agricultural production systems primarily as a silica amendment, and has also benefit of supplying small amounts of potassium. Potassium silicate offers growers these performance benefits (resistance to mineral stress, decreases climate stress, prevents insect damage from sucking insects, reduces fungus damage by preventing fungus from penetrating leaf surface, improves strength , increases growth and yield, reduces stress from heavy metal toxicity in soils, control root knot and sting nematodes, helps plants to resist toxicity from different minerals, aids in resistance to drought by reducing water loss, improves leaf erectness, reduce susceptibility to lodging in grasses, fights heat stress and improves photosynthesis efficiency).The correct amount of silicon levels in the plant tissue will increase tolerance of zinc deficiency along with protection from excessive or toxic levels of phosphorus, manganese, sodium and aluminum (Malhotra et al. , 2016). Chitosan is a high – molecular weight cationic polysaccharide produced by the deacetylation of chitin. The compound is non – toxic, non – allergenic, edible, safe and able to induce host defence responses, including the accumulation of phytoalexins (Reddy et al., 2000), the deposition of cell wall materials (Benhamou et al., 1998) and the lignifications of tissues (Lesney, 1989). Chitosan induces a series of defence reactions correlated with enzymatic activities, through production of glucanohydrolases, phenolic compounds and synthesis of specific phytoalexins with antifungal activity. In addition, it increased harvested yield, and due to its ability to form a semi permeable coating, it extends the shelf life of treated fruit by minimizing the rate of respiration and reducing water loss (Bautista – Baños et al., 2005). Therefore, the present study was conducted to control excessive premature fruit drop, decreasing fruit set and improvement Washington navel orange yield and quality growing under unsuitable climate conditions by application of some micronutrients and plant growth regulators. SUMMARY AND CONCLUSION This study was conducted in the two successive seasons (2011 - 2012) and (2012 -2013) on Washington Navel orange trees (Citrus sinensis lin, Osbek) budded on Sour orange rootstock and grown in two private citrus orchards, i.e. "El-Shawarby Horticulture orchared", Agriculture Road at 11 km, El-Qaluobia Governorate, Egypt and the second was "El-Shoruk Horticulture orchared", Cairo-Alex. Deseret Road at 74 km, El-Monufia Governorate, Egypt. In the first garden, Washington navel orange trees were about 20 years old grown on clay loamy soil at 5 x 5 m. Meanwhile, in the second garden, Washington navel orange trees were about 11 years old grown on sand loamy soil at 4 x 6 m. This study aimed to improve fruit set and yield of Washington navel orange trees through foliar application of some different safe pre- harvest treatments. As well as preserve of fruit quality during cold storage durations. The present work included two experiments: The first experiment included 9 treatments, i.e. control, 20 and 30 ppm GA , 100 and 200 3 ppm boric acid, 62.5 and 125 ppm chelated zinc as well as 100 and 200 ppm K O.4SiO . These treatments were applied twice at the full bloom 2 2 stage (at the third week of March) and the second time at the petal fall stage (at the first week of April). The second experiment included 3 treatments, i.e. water containing 0.5 % acetic acid (control), 250 and 500 ppm chitosan. These treatments were applied as foliar spraying twice at one month before the beginning of fruit color break (second week of September) and the second at one month before harvest