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Abstract The present investigation was conducted during three successive seasons 1985, 1986 and 1987 to study the nutritional status, vegetative growth, yield and fruit quality of Washington navel orange, Valencia orange and Balady mandarin trees in relation to orchard location at three different regions within the Kaliobia Governorate. Based on the results obtained during the first two seasons, a correction treatment, using potassium dihydrogen phosphate foliar sprays was applied (in the third season) to the citrus cultivars at the different locations under stud" ~ "and the response of the trees to the correction treatment was evaluated. Furthermore, the data sets obtained from these.experiments and locations for washington navel orange under study were used to develop a preliminary foliar nutrients norms by calcUlating the interrelationships between the levels of foliar nutrients and yield" ~ " This set of interrelationships led to the selection of reference values used to calculate the Diagrtosis and Recommendation Integrated System (DRIS) indices,;- This research introduces this new system to the Egyptian Agriculture. DRIS uses nutrient concentration ratios, rather than••the concentrations theaseleves, to interpret tissue analysis. Therefore, it is based on nutritional balance and indicates not only the nutrient most likely to be limiting, but also the order in which other nutrients are likely to become limiting. Proper developoment and interpretation of ORIS indices is crucial as they reflect relative nutrient insufficiencies or excesses. Three orchards were selected, each located at a different region namely Moshtohor, Kafr Hassan and Meet-Kinanah. Every orchard involved the three citrus cultivars used in this st.udy., All trees were growing on the sour orange rootstock. Trees of both orange· cultivars were about 20-year-old and planted 5 meters apart, while mandarin trees were l5-year" ~ "old and planted 3.5 meters apart. The three orchards received approximately the same cultural care. In each experimental orchard, ten healthy trees of every cv., uniform as possible in vigour, were selected carefully as being representatives of both the cultivar and the locality. The soil of each orchard was mechanically and chemically analysed at the three depths i.e. ”0-30, 30-60 and 60-90 cm from the soil surface”. The whole set of tree population was used in the l" ~ " experiment, during 1985 and 1986 seasons, to study the nutritional status of the trees in relation to vegetative growth, yield and fruit quality A.I.b. Leaf R , as influenced by KB2P04 foliar sprays: The three citrus cultivars showed generally a positive response in their leaf N level. However, the response of Balady mandarin was more pronounced at all orchard locations, while both Washington navel orange and Valencia orange cultivars showed an increase in leaf N level only at Kafr-Hassan and Meet-Kinanah orchards, respectively. Generally, foliar sprays had a limited effect on leaf N level at Moshtohor, regardless of the citrus cv. It is not easy to explain such results, but it may reflect the differences in the specific behaviour af each cultivar under certain set of conditions A.2. Phosphorus: A.2.a- Leaf P , in relation to orchard location: The leaf P level in all citrus cvs at the three orchard locations tended to be lower than the optimum range. Such trend was more pronounced for the two orange eva. at Moshtohor. While leaf P level was generally, near the opti" ~ "um at Meet-Kinanah. This could be attributed to the relatively higher soil content of available P in the Meet-Kinanah orchard as revealed from soil analysis. (183) A ..2;b- Leaf P •.as influenced by KB2PO” foliar sprays: KH2P04 foliar sprays increased leaf P % in all citrus cvs , Such increment was more pronounced with Balady mandarin. On the other hand, trees at Meet-Kinanah showed the least response in this respect. A" ~ "3" ~ " Potassium: A;3;a" ~ " Leaf K •.in relation to orchard location: The K level in all citrus cvs , at the three orchard locations was Low , However, leaf K content of trees at Meet-Kinanah orchard was higher than that of Kafr Hassan, while, trees of Moshtohor orchard were the lowest in this respect.. Thes-e--result’sare positively correlated with soil potassium content of those orchards. A.;3.;.b-· Leaf K •.as influenced by KB2PO” foliar sprays: Leaf K level of sprayed trees was significantly increased over those of the unsprayed ones in all orchard regions except with Washington navel " ~ "orange at Meet-Kinanah, where differences were not significant at 1% level. Trees of Meet Kinanah orchard were originally in a better leaf K status than the trees at the other two locations. A" ~ "4. calcitm: The three citrus cvs. at Kafr Hassan orchard showed higher leaf Ca level than those of Moshtohor or Meet-Kinanah. Trees sprayed with KH2P04 showed a slight decrease in leaf Ca % below the control trees. Magnesium: Significant differences in leaf Mg % for all citrus cultivars were recorded in relation to different orchard locations. Trees in Moshtohor orchard had the highest leaf Mg level, but those in Meet-’Kinanah had the lowest level while trees in Kafr Hassan had values inbetween, in this respect. KH2P04 foliar sprays did not affect appreciably the leaf mg content in any of the different citrus cvs. under study, except Washington navel orange either in Moshtohor or Kafr Hassan where leaf Mg level was significantly decreased in sprayed trees. Sodiuu Generally, leaf Na content of--citrus evs in Moshtohor orchard was at a higher level over those of trees in the other two regions. Such higher level was more pronounced in both Navel orange and Balady (186), level, while Balady mandarin had the highest Mn level in the same orchard.. This condition may be related to the amount of growth achieved by trees of different cvs. at different locations and subsequently its diluting effect on the Mn leaf content. Leaf Mn % was not influenced by. KH2P04 sprays in most cases except with Valencia orange in Moshtohor and Balady mandarin at Kafr Hassan, where the Mn level was positively affected. A.9- Zinc: All trees under study in the three different locations showed that leaf Zn content was lower than the optimum range. However, trees in the Moshtohor orchard had generally the highest leaf Zn % followed by those at Kafr-Hassan and Meet-Kinanah regions in a descending order, for all citrus evs. under study.KH2P04in leaf Zn % foliar sprays resulted for both orange cvs , in an increase but no response was recorded for Balady mandarin trees. B,; " ~ "ee growth: B" ~ "l. " ~ "ee canopy circtmference: Orange trees at Kafr Hassan orchard had the largest canopies while Balady mandarin trees at Moshtohor were larger than those at Kafr-Bassan. On the other hand, smallest canopies were developed on trees of Valencia orange and Balady mandarin at the Meet-Rinanah orchard. KH2P04 foliar sprays increased tree canopy circumference over the unsprayed ones. However, such . increase was more pronounced at Moshtohor orchard for both orange cvs. while at Meet-Rinanah the response was appreciable only for Balady mandarin. B.2.; Tree height: Washington navel orange produced the tallest trees at Meet-Rinanah,while Valencia orange and Balady mandarin trees were taller at Kafr-Hassan than the corresponding ones at the other two regions. Generaliy, tree height was not appreciably influenced by KH2P04 foliar sprays for all citrus cvs , except Valencia orange at, Meet-Kinanah orchard where sprayed trees were significantly taller than the control •. B" ~ "3" ~ " 2runk circuaference: All citrus cvs. at Kafr Hassan produced the largest trunk circumference while Washington navel orange, at Moshtohor, had the smallest trunk circumference.. But valencia orange and Balady mandarin were both smaller at Meet-Kinanah orchard .. KH2P04 foliar sprays induced a slight increase in trunk circumference· that was not significant in most cases,; B" ~ "”,,; Leaf dry weight: . All citrus cvs. showed large variability in leaf dry weight not only from one orchard location to another but " ~ "lso from one growing season to another; Generally, KH2P04 foliar sprays caused a slight increase in leaf dry weight of different cvs. at different locations that was not significant in most cases. Generally, it could be concluded that, although vegetative growth parameters differed according to both citrus cultivar and orchard location, but a trend was detected for most cases. The highest values for tree canopy circumference, tree height and trunk circumference were observed at Kafr-Bassan orchard, except that, tree height of Navel orange and canopy circumference of Balady mandarin were higher’ at Meet-Kinanah and Moshtohor orchards, respectively; Moreover, the KH2P04 foliar sprays generally increased growth measurements, but the increase in tree canopy was more pronounced especially at Moshtohor and Meet-Kinanah orchards for both orange cuItivars and the Balady- mandarin, respectively" ~ " These results may be correlated to the leaf mineral status of these citrus cvs, in relation to orchard location; where Moshtohor orchard showed generally the lowest level of many nutrient elements, especially the critical level of P and K. Furthermore, orange trees at Moshtohor responded well to theKH2P04 correction treatment.. Co; Yield and Biennial Bearing Indez: C.;l" ~ " Yield: Washington navel orange trees at Meet-Kinanah orchard produced the highest yield during the three seasons of study.. However, the same orchard yielded the least crop of both valencia orange and Balady -,» mandarin, when the latter trees were in the on-year status. Valencia orange trees produced the highest yield at Moshtohor allover the period of study.. The alternate bearing habit was clear in’ .B.a.l.ady mandarin trees at all locations.. But tree yield showed two opposite trends for Balady mandarin in relation to orchard location; ·where in seasons of the on-year status, both Moshtohor and Kafr -Hassan gave high but comparable yields. The reverse was true in the off-year season, where the yield of Meet-Kinanah was the highest. the Balady mandarin, respectively" ~ " These results may be correlated to the leaf mineral status of these citrus cve, in relation to orchard location; where Moshtohor orchard of many nutrient level of P and showed generally the lowest level elements, especially the critical K. Furthermore, orange trees at Moshtohor responded well to the KH2P04 correction treatment. C; Yield and Biennial Bearinq Index: C .l.,.; Yield: Washington navel orange trees at Meet-Kinanah orchard produced the highest yield during the three seasons of study. However, the same orchard yielded the least crop of both valencia oranqe and Balady mandarin, when the latter trees were in the on-year status. Valencia orange trees produced the highest yield at Moshtohor allover the period of study. The alternate bearing habit was clear in’ ’salady mandarin trees at all locations. But tree yield showed two opposite trends for Balady mandarin in relation to orchard location; where in seasons of the on-year status,· both Moshtohor and Kafr -Hassan gave high but comparable yields. The reverse was true in the off-year season, where the yield of Meet-Xinanab was the highest. the yield increase in these non-parthenocapic citrus cultivars. In fact, magnesium level may be considered as one of the reasonable factors due to its necessity for seed development. C.2. Biennial bearing indez: Biennial bearing was quite obvious in the Balady mandarin than in both Washington navel and Valencia orange trees. However, all citrus cultivars showed the highest tendency toward alternate bearing at the Moshtohor location and the least alternate bearing at Meet-Kinanah. Kafr-Hassan orchard was in between in this respect. D. Fruitquality: D.I. Fruitphysical characters: Generally r . both orange cuItivars tended to produce the highest fruit weight at Meet-Kinanah orchard with minor variability during the seasons" ~ " However, the reverse was true for Balady mandarin where fruits of Meet-Kinanah were the smallest. XH2P04 foliar sprays resulted in a general increase in fruit weight of all citrus cvs , under study. But such increase lacked .significance in most cases. Fruit size and dimensions behaved, in most cases, in a similar way as fruit weight" ~ " Fruit shape index showed no apreciab1e difference due to orchard location for both Washington navel orange and Balady mandarin during all seasons of study. However, Valencia orange fruits at Moshtohor tended to be oblong, while fruits of the same cultivar, at both Kafr-Hassan and Meet-Kinanah orchards, tended to be round or slightly compressed. KH2P04 foliar sprays did not affect appreciably the fruit shape index of any of the three citrus cva. at all orchards. Regarding fruit peel thickness, fruits of both orange cultivars had thinner rind at Moshtohor, however, differences were more pronounced with Washington navel orange •. On the other hand, Balady mandarin fruit peel was thinner at Meet-Kinanah than at.the other two locations. KH2P04 foliar sprays increased peel thickness for all citrus cvs., however, Valencia orange was more responsive. Meanwhile, both orange cva. at Moahtohor, positively responded to KB2PO4, sprays while Balady mandarin took the opposite trend" ~ " Considering fruit juice weight, no clear trend could be noticed in relation to orchard location, when each season was considered spearately. However, taking the average of the three seasons, reveal a similar trend to that .found for fruit weight 7 where highest values were obtained from Meet-Kinanah regarding the two orange cvs. and Moshtohor regarding Balady mandarin. KH2P04 foliar sprays slightly increased fruit juice weight, such increases were not significant in most cases. D.2" ~ " Fruit cheadcal properties: Fruit juice T.S.S.% varied from one season to another. However, taking the average of the three seasons, fruit juice T ..S..S.. showed the lowest values for the two orange cultivars at Meet-Kinanah ozohard; Meanwhile, Balady mandarin, gave comparable fruit juice T ..S.S..at all locations.. Fruit juice T ..S..S,; % was decreased in response to KB2P04 foliar sprays for all cultivars, especially at both Kafr-Hassan and Meet-Kinanah .. Trees at Moshtohor orchard produced fruits having the lowest content of juice acidity, especially Valencia orange and Balady mandarin during all seasons of study. On the other hand, all cvs ..at Kafr-Hassan produced fruits with the highest percentage of titratable acidity; .KH2P04 foliar sprays increased the fruit total acidity of both Washington navel orange and Balady mandarin at Meet-Kinanah: but was not effective at the other two locations; An opposite trend was noted for Valencia orange. T.S.S./acid ratio showed highest values for all cvs , under study at Moshtohor during the three seasons. Moreover, differences, in this respect between the other two locations were negligible, in most cases. Fruit juice T.S.S./acid ratio tended to increase in response to KH2P04 foliar sprays, at both Moshtohor and Kafr-Hassan orchards with all cvs , However, an • .c opposite trend was noted at Meet-Kinanah • .Ascorbic acid content was highest in fruit juice of Meet-Kinanah orchard over those at the other two locations, especially Balady mandarin.; This may be related to the relatively higher leaf K , of trees at Meet-Kinanah orchard; significantly induced higher ascorbic acid content in fruit juice over those of unsprayed trees. Generally, the noted differences in fruit physical and chemical characteristics, in relation to orchard environment or to KH2PO4 foliar sprays could be a response to these factors acting in two different ways; the first being a direct effect, and the second is an indirect one resulting from ..the unparallelled responses of trees in their vegetative growth and fruiting behaviour, and consequently the interrelationships involved in this respect. B" ~ " PreliJI.inary application of the ORIS technique: Mean and Coefficient of variation (cv) values for the present data of nutrient concentration ratios have.- been calculated and used for the calculation of ORIS indices for nutrient a" ~ "alysis interpretation of Washington navel orange. The indices so calculated were compared to sufficiency range diagnoses, and were tested for accuracy in predicting yield response based on the data available in this work. In general, where the sufficiency range method made a diagnosis, it agreed with the ORIS diagnosis; ORIS indicated not only the most-limiting nutrient, but also the’ order in which other nutrients would likely to become limiting. P. Concluding R..ar.ks: 1- A judicious fertilizer program should be based on soil and leaf analysis of the concerned orchard. Other factors of the local environment, cI96} in relation to the concerned cultivar, should also be considered. 2- The Diagnosis and Recommendation Integrated System (ORIS) developed .by Beaufils, should be applied to serve as a foliar diagnostic tool capable of revealing mineral imbalances and predicting the fertilizer and other treatments required by a given crop at a given site to enhance the chances of obtaining a higher yield. Therefore, this system may overcome many limitations encounte" ~ "ed in applying the critical or sufficiency’level appro" ~ "ch in diagnosing mineral nutritional problems. 3- The application of potassium in the fertilization program may prove to be beneficial in many citrus orchards,;; 4- The method of application of phosphorus fertilizers should be reevaluated to achieve better availability and utilization of the a,.mounts applied of that element. |