The objectives of this study were to test the effects of melatonin (N-acetyl-5-methoxytryptamine), a natural compound of edible plants on the rooting of certain commercial sweet cherry rootstocks. Shoot tip explants from previous in vitro cultures of the cherry rootstocks CAB-6P (Prunus cerasus L.), Gisela 6 (P. cerasus × P. canescens), and M × M 60 (P. avium × P. mahaleb) were included in the experiment. The effect of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) alone or in combination with melatonin was tested concerning their rooting potential. Seven concentrations of melatonin (0, 0.05, 0.1, 0.5, 1, 5, and 10 μM) alone or in combination with 5.71 μM of IAA or 4.92 μM of IBA were tested. For each rootstock, 21 treatments were included. The explants were grown in glass tubes containing 10 mL of substrate. The parameters measured include rooting percentage, number of roots per rooted explant, root length, and callus formation. The data presented in this study show that melatonin has a rooting promoting effect at a low concentration but a growth inhibitory effect at high concentrations. In the absence of auxin, 1 μM melatonin had auxinic response concerning the number and length of roots, but 10 μM melatonin was inhibitory to rooting in all the tested rootstocks. The final conclusion of this experiment is that exogenously applied melatonin acted as a rooting promoter and its action was similar to that of IAA.

The agricultural and medicinal plant pomegranate (Punica granatum L. cv. Wonderful) was studied to examine the effects of wounding of cuttings and to test the effects of different concentrations of indole-3-butyric acid (IBA), gibberellic acid (GA 3 ), hydrogen peroxide (H 2 O 2 ), melatonin (MEL), and ascorbic acid (ASC) on rooting of the shoot cuttings under mist. The data indicated that IBA had a positive influence on the rooting percentage in wounded and nonwounded cuttings. The best rooting was achieved with very thin cuttings (3-4 mm in diameter). The percentage of rooting (100.0 ± 0.0) and the number of roots per plant (15.2 ± 2.4) were positively affected if the point of severing was at an internode of the cutting. It was found that 17 mg L -1 H 2 O 2 in combination with 1000 mg L -1 IBA produced the longest roots, whereas 500 mg L -1 GA 3 in combination with the same IBA concentration (1000 mg L -1 ) reduced root length. In addition, the human hormone MEL at an application of 1.16 mg L -1 can be substituted for IBA to produce positive effects on rooting, while 352.24 mg L -1 ASC alone or in combination with IBA also promoted rooting.

This chapter aims to provine some information on mineral nutrition and salt tolerance of olive trees. The topics discussed are: the needs of olives for N, P, K and their concentration in various plant parts; the annual needs for N, P, K and Ca for various fruits and the annual variations in N, P, K, Ca and Mg concentrations in leaves as well as N distribution in fruiting olive shoots; the concentrations of various nutrients considered as being adequate; nutrient stress and growth; nutrient deficiency or excess and photosynthesis; N excess and quality of olive oil and table olives; roles of N and its assimilation, kinetics of nitrate absorption and effect of N form on growth; olive culture and the nitrate accumulation problem; nitrates leaching from olive orchards; roles of K, P, Ca and Mg and their absorption; roles of B and Mn; response of olive trees to salinity; olive fertilizer application and slow-release fertilizers.

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The chemical and biochemical composition of olives relies on some agronomical factors, one of which is the cultivar. In this study, fruits and leaves of 11 Greek olive cultivars were examined concerning their phenol and oleuropein concentrations. Fruit antioxidant activity was determined as well. The obtained results showed that significant differences existed among cultivars regardless of the tissue or the measured parameter. In general, leaves had higher total phenol and oleuropein concentrations than fruits. Finally, the highest oleuropein concentration in fruits was recorded in ‘Pikrolia Kerkiras’ followed by ‘Romeiki’, ‘Megaritiki’, ‘Kothreiki’, and ‘Kalamon’. These cultivars may constitute the raw material in the industrial production of oleuropein.