Abstract: Aim: The study aim is to investigate the effect of different fertilization and harvesting time on the growth, head characters and nutrition quality on endive under sandy soil. Methodology: A field experiments were carried out during the winter seasons 2013/2014 and 2014/2015 to study the influence of different fertilization like mineral nitrogen and biofertilizer alone or in combination and time of day for harvest on growth, head character and nutritional quality of endive. Growth characters like plant height, number of leaves per plant and leaves dry matter (%) were significantly influenced by different fertilization treatments. However, plant height and number of leaves per plant characters were insignificant differences affected by time of day harvest, in both growing seasons. But the highest leaves dry matter (%) was obtained when plant harvest at midday (in the afternoon) in both growing seasons. Whereas the head weight and head diameter attributing characters were significantly influenced by different fertilization treatments. Significantly maximum head weight (g) and head diameter (cm) were recorded by 100% mineral nitrogen fertilizer followed by 75% mineral nitrogen fertilizer. Results: Also, the results reflected that the best time of harvest that gave the significant highest mean value of this characters were given by using the evening harvest, in both growing seasons. The highest nutritional quality parameters like total phenol, TSS and ascorbic acid were obtained when plant received 100% biofertilizer and afternoon harvest, in the both seasons. The data showed that there was significant effect of different fertilization treatments on total chlorophyll content. In both seasons, the highest value was obtained with 100% mineral nitrogen. The data, also indicated that there were no significant effects of all harvesting time treatment on total chlorophyll content.
INTRODUCTION
Endive (Cichorium endivia L.), an annual plant, belonging to leafy vegetables group, has become very popular in west European countries, yet it has been relatively less known in Egypt. Endive characterized a considerable nutritive value as well as, distinctive, slightly bitter taste. The plant occurs in two botanical varieties, curly leaves or smooth leaves1.
Leafy vegetables, rich in vitamins, fiber and minerals are good for human health. Vegetable salads are popular because they contain more vitamins than cooked vegetables and salads are easy to make2,3.
The nutrition composition of produce and may ultimately play a greater role in food quality. Cultivation the practices likely to affect food quality include humus management technique such as bio-fertilizers, mineral fertilizer, soil management, environmental condition and harvest4,5.
Nitrogen is usually the most abundant element in plants growth and consequently yield. It has essential role as a constituent of protein, nucleic acids, chlorophyll and growth hormones. Intensive application of fertilizer caused an excess of nitrogen for crops. There is strong evidence that some of the excess nitrogen taken up by the plant is not converted to protein but remains as non-protein nitrogen. This is not only inefficient use of nitrogen by the plant but leads to inefficient use by the animal and the risk of ill effects on human beings eating the plant6.
Frequently, farmers use excessive rates of fertilizer especially, nitrogen in vegetables and due to increasing of costs of fertilizer and the dangers of increasing soil salinity and pollution of the agriculture environmental as well as significant increase in nitrate accumulation in several vegetable crops especially, leafy vegetables5,7,8.
Nutrient management involving use of chemical fertilizers combined with bio-fertilizers in balanced proportion may be helpful to increase the productivity of vegetable crops9.
A further potentially important factor is the time of day that the leaf is harvested. Current farming practice is to harvest leaves at first allowing the crop to be shipped, processed or packed on the same day. However, plant and leaf functional attributes are known to alter diurnally and this could impact on the process ability traits of the leaves10.
This study aims at investigating the effect of different fertilization and harvesting time on the growth, nutrition quality on endive under sandy soil.
MATERIALS AND METHODS
Two field experiments were conducted during the growing seasons 2013/2014 and 2014/ 2015 at the experimental farm of South Tahrir Horticulture Research Station, at the Ali Mubarak village, El-Bostan region, Behera, Egypt. Physical and chemical properties of the two experimental sites were determined according to methods described by Black11 and presented in Table 1.
Endive seed cv. Fransawy (curly leaves) were sown on first September and transplanted on first October in soil with three replicates, in both seasons. Transplants were planted with 20 cm apart on both sides of rows with 70 cm width. In the two experiments, the used experimental layout was Randomized Complete Blocks Design (RCBD) in split-plot system with three replications. The fertilizer treatments were, T1-100% minerals nitrogen fertilizer (80 kg N Fed–1), T2 100% biofertilizer (2 kg microbien Fed–1), T3 combination between minerals and biofertilizer microbien (50% mineral nitrogen+50% microbin), T4 (75% mineral nitrogen+25% microbin) and T5 (25% mineral nitrogen fertilizer+75% microbin). While, the three harvesting time (i.e., early harvest in the morning, at 7 AM o’clock, mid harvest in the afternoon, at 12 PM o'clock and late harvest in the evening, at 7 PM o’clock from day) were occupied as sub-plot. Root of endive transplants were dipped into the biofertilizer prepared solution (According to the Ministry of Agriculture Recommendation) immediately before transplanting. An additional 2 kg Fed–1 of the mean biofertlizer wax mixed with about 25 kg soil and add to the soil at two weeks after transplanting. Phosphorus and potassium fertilizers were fertigated at rates of 70 and 100 kg P2O5 and K2O Fed–1, respectively as ammonium nitrate (33.5% N), phosphoric acid (58%) and potassium sulfate (48%), respectively, according to the recommendations for commercial production of endive plant as outlined by Ministry of Agriculture and Land Reclamation-Arab Republic of Egypt.
| Table 1: | Some soil physical and chemical properties of the experimental sites, during the two winter seasons of 2013/2014 and 2014/2015 |
| Table 2: | Influence of different fertilization, harvest time and their interaction on growth characters of endive during the winter season 2013/2014 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
The recommended agriculture practices for commercial endive production were followed. Endive were harvested 70 days after transplanting.
Vegetative growth characteristics: The sample were taken at harvest stage, in both seasons. Five plant were taken from each sub plot, to measure plant height (cm), number of leaves per plant and dry matter of leaves (%) was determined after drying the leaves at 70°C for 72 h.
Head characters: The sample were taken at harvest stage, in both seasons. Five plant were taken from each sub plot, to measure head fresh weight (g) and head diameter (cm).
Nutritional quality: The total soluble solids were measured in the juice of the leaves using a portable digital refract meter (Atago Co. Ltd., Tokyo, model PR-1). The nitrates were determined according to Cataldo et al.12.Total soluble phenols were determined according to Scalbert et al.13 and expressed as mg g–1 fresh weight. Leaves vitamin C was measured by titration with iodide potassium14. Nutrient content, phosphorus was determined calorimetrically; using spectrophotometer at 650 nm, according to Murphy and Riley15 and potassium was determined by flam photometer as described by Cottenie et al.16 of the leaves were expressed as a percentage on the dry weight basis.
Statistical analysis: Treatment means were separated and compared using the LSD test at 0.05 level of significance according to Snedecor et al.17. The statistical analysis was performed using Co-Stat software package for windows.
RESULTS AND DISCUSSION
Vegetative growth characteristics: Regarding the effects of different fertilizer on plant height character of endive in sandy soil, the results of Table 2 and 3 revealed that use of the different fertilization treatments showed that the plant height of endive were produced with application of 100% of mineral nitrogen fertilizer compared with other treatments, in both growing seasons. Meanwhile, when the inoculation with biofertilizer was amended with 75 or 50% mineral nitrogen not significant differences were obtained. On the other hand, it is clear that application of biofertilizer solely significantly decreased plant height compared with the other treatments. Also, the data are shown in Table 2 and 3.
| Table 3: | Influence of different fertilization, harvest time and their interaction on growth characters of endive during the winter season 2014/2015 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
Plants were harvested at three times, early time (morning), mid time (afternoon) and late time (evening) there were insignificant differences affected by harvest time, in both growing seasons.
The interactions in between different fertilization and harvest time are presented in Table 2 and 3. The results indicated that the interaction between 100% mineral fertilizer with early or late harvest time were significantly higher than other interactions and gave the highest endive plants, in the first season Table 2. While, the interactions 100% mineral nitrogen fertilizer with any harvest time gave the highest mean value in plant highest, in second season Table 3.
Regard to the number of leaves per plant, in both growing seasons, the obtained results in Table 2 and 3 indicate that the 100% mineral nitrogen fertilizer or 75% mineral nitrogen fertilizer inoculation with 25% of biofertilizer significantly resulted in the highest values of leaves number per plant as compared to other tested treatments. However, there were no significant differences among the treatments of inoculation with biofertilizer either solely or coupled with half dose of minerals nitrogen fertilizer treatment. The number of leaves per plant was not affected by harvest time in Table 2 and 3, in both growing seasons.
The interactions between different fertilizer and harvest time are presented, also in Table 2 and 3. Data indicated that there were significantly differences among the interactions, in both growing seasons. When plants receive 100% mineral nitrogen fertilizer the highest mean values were obtained from late harvest (evening), in two studied seasons.
The effect of different fertilization on leaves dry matter% of endive plants in sandy soil are presented in Table 2 and 3. The results presented that there was significantly differences among each different fertilization treatments in this trait. The highest leaves dry matter% was obtained when plant received 100% mineral nitrogen fertilizer or 100% biofertilizer gave the highest mean value in the first season. While, the highest leaves dry matter% value was determined in 100% biofertilizer treatment (17.62%) in the winter 2014 and 2015.
From the aforementioned results, under the present conditions, it could be concluded that vegetative growth of endive plants expressed as plant height, leaves number per plant and dry matter of leaves%, it could be concluded that the increase in vegetative growth may be attributed to the beneficial effects of non-stimulating the meristmatic activity for producing more tissues and organs and N play major roles in structural proteins and other several macromolecules related with growth plants on onion and lettuce, respectively18,19.
| Table 4: | Influence of different fertilization, harvest time and their interaction on head characters of endive during the two winter season 2013/2014 and 2014/2015 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
However, leaves dry matter% improvement when used 100% biofertilizer. Also, the improving in plant growth associated with decrease in N level. The decrease of N application with used mineral fertilizer with bio-fertilizer was reported in many investigation such as, Shehata et al.7 on celery plant and Shahein et al.20 on amaranths plant).
The results presented that there was significantly differences among each of harvest time treatments in this trait. The highest leaves dry matter% was obtained when plant harvest at midday (afternoon), in both seasons of study Table 2 and 3.
As for the interaction effects between the different fertilization and harvest time on leaves dry matter% character, the results presented in Table 2 and 3 demonstrated generally that the comparisons among the mean values of leaves dry matter% for the different treatments that gave the highest mean values was the combinations between application of 100% mineral fertilizer at mid harvest (afternoon) in the first season and 100% biofertilizer treatment at mid harvest, in the second season.
Head character: The results concerning the effects of different fertilization on head fresh weight of endive under sandy soil in Table 4 indicated significantly increases in the weight due to use of the different fertilization treatments, through the two seasons. The obtained results clarified that the significant highest mean value of head fresh weight (399.22 and 422.33) was given by application of fertilizer at 100% minerals nitrogen, followed by 75% minerals nitrogen+25% biofertilizer, in both growing seasons.
According the results in Table 4 there were significant differences among the three studied harvest time in relation to their effects on head fresh weight character, in both growing seasons. The results reflected that the best harvest time that gave the significant highest mean value of this character was given by using the evening harvest (326 g), in the first season and the evening harvest (369.26 g), followed by morning harvest (364.26 and 364.63 g), in the second season.
The application of different fertilization to the grown endive plants, the obtained results, in the two seasons, cleared that using the mineral fertilizer at 100% mineral nitrogen gave significantly higher head diameter mean values (20.83 cm) than other different fertilizer treatments, followed by 75% mineral nitrogen +25% biofertilizer (20.23 cm), in both two seasons.
| Table 5: | Influence of different fertilization, harvest time and their interaction on nutritional quality of endive during the winter season 2013/2014 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
Table 4 showed also that the harvest time reflected significant increments in head diameter character with the three tested harvest time, in both seasons. The highest mean values of this character was obtained by evening harvest (17.83 and 17.23 cm), in the two seasons.
Concerning the results in Table 4 the interaction effects between the different fertilization and harvest time on head characters, generally, the endive plant was received 100% mineral nitrogen fertilizer with evening harvest time gave the highest mean value of head characters compare other treatments, in both growing seasons.
The present results, in general are in agreement with those obtained by Shehata et al.7, Hosseny and Ahmed19 and Shahein et al.21.
Nutritional quality: Total soluble solid, total phenol contentand ascorbic acid were affected by different fertilization Table 5 and 6. The highest nutritional quality was obtained when plant received 100% biofertilizer, in the both growing seasons. Also, the data shown in Table 5 and 6 the highest mean values of this characters were obtained by afternoon harvest, in the two seasons.
As for the interaction effects between the different fertilization and harvest time on nutritional quality characters, the results presented in Table 5 and 6 the mean values of nutritional quality for the different treatments that gave the highest mean values was the combinations between application of 100% biofertilizer at mid harvest (afternoon), in the two seasons.
The effect of different fertilization application on vitamin C found in this study, has also been demonstrated in reviewer22,23. Nitrogen fertilizers especially at high rates, seem to decrease the concentration of vitamin C in many fruit and vegetables. Plant growth is generally enhanced by the nitrogen fertilization, so that a relative dilution effect may occur in the plant tissues. Nitrogen fertilizers are also known to increase plant foliage and thus may reduce the light intensity and accumulation of vitamin C in shaded parts.
| Table 6: | Influence of different fertilization, harvest time and their interaction on growth characters of endive during the winter season 2014/2015 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
Data obtained in Table 7 and 8 showed that there was significant effect of different fertilization treatments on total chlorophyll content. In both seasons, the highest value was obtained with 100% mineral nitrogen fertilizer gave 1.866 and 1.856 in the first and second seasons, respectively. Also, the application of biofertilizer 100% significantly decrease the content of total chlorophyll compared with other treatments similar finding was gained by Migahed et al.24 and Shehata et al.7. on celery, Muzafar23 on globe artichoke From the data in two seasons, it is clear that there were not significant effects of all harvesting time treatment on chlorophyll content.
Data in Table 7 and 8 indicate that, during the two seasons, the highest values of nitrate content in the leaf tissues were obtained from 100% mineral nitrogen fertilizer (80 kg Fed–1). Whereas, the lowest values of nitrate content in the leaf tissues biological fertilization100%. These results are confirmed by Migahed et al.24 and Hassan et al.25 on globe artichoke. Also, in this respect Hosseny and Ahmed19, Shahein et al.21 and Boroujerdnia et al.26 reported that reduced nitrogen fertilizer with biofertilizer decrease nitrate accumulation in lettuce and Shehata et al.7 in celery plant. Also, Ahmed et al.27 found that significant decreases in nitrate accumulation when the lettuce plant treated with all studied bio-fertilizers, especially those plants treated with nitrogen.
The effect of harvesting time on nitrate accumulation was significant and amount was lower in afternoon in comparison to another harvest time. Because, during day trough solar radiation increasing nitrate reeducates activity and nitrate assimilation and thereby decreasing nitrate content of plants explained the rate of NO3 up take is substantially higher in day time than in night time28,29. This is apparently due to higher soluble sugar content of the during day time than in night. In this case similar result has been reported by Boroujerdnia et al. 26 on lettuce.
Data in the same tables show that the highest values of P and K were recorded in leaves in two seasons, the highest values of P and K content in the leaf tissues were obtained from 100% mineral fertilizer of N 80 kg Fed–1. Whereas, the leaf P and K content were not significant in the second season but in the first season the highest value of P content were obtained from the evening treatment and the highest value of K content were obtained from the morning treatment. These results were agreement with Levander30, who found the different leaf mineral concentration were mainly dictated by species and to a lesser degree were due to effect of light intensity at the time of harvest.
| Table 7: | Influence of different fertilization, harvest time and their interaction on total chlorophyll, nitrate content, phosphorus and potassium in leaves, during the winter season 2013/2014 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
| Table 8: | Influence of different fertilization, harvest time and their interaction on total chlorophyll, nitrate content, phosphorus and potassiumin leaves, during the winter season 2014/2015 |
| Values followed by the same alphabetical letter(s) in common, within a particular group of means in each character, do not significantly differ, using revised LSD test at 0.05 level of probability | |
CONCLUSION
Consequently, the results of this study suggest that cultivated endive had increased the growth and head characteristics with the application of different fertilization and harvest time. On the other hand, the lowest nitrate accumulation and highest of nutrition value such as vitamin C, TSS% and total phenol were determined in biological fertilization 100% application when compared with other different fertilization. When considering the nutrition and nitrate accumulation in leafy vegetables are harmful for human health, therefore, the usual fertilizer of NPK 50%+Bio 50% or NPK 75%+Bio 25% is firstly suggested that it should be applied to not only have better yield and agronomic traits but also produce healthy crops for human nutrition in cultivated endive. The combination of mineral fertilizer and biological fertilizer of nitrogen under sandy soil give the similar obtained in head weight and quality in other soils.
ACKNOWLEDGMENTS
Authors are thankful to Dr. R.M. Ali assistant Professor of vegetable Res. Dept. National Research Centre, Dokki, Cairo, Egypt, for providing necessary facilities in this study.