The effect of the zinc (Zn) nutritional status on the rate of phytosiderophore release was studied in nutrient solution over 20 days in four bread wheat (Triticum aestivum cvs. Kirag-66, Gerek-79, Aroona and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes differing in Zn efficiency.Visual Zn deficiency symptoms, such as whitish-brown necrosis on leaves and reduction in plant height appeared first and more severe in Zn-inefficient durum wheat genotypes Kiziltan-91, Durati and Kunduru-1149. Compared to the bread wheat genotypes, all durum wheat genotypes were more sensitive to Zn deficiency. BDMM-19 was the least affected durum wheat genotype. Among the bread wheat genotypes, Kirkpinar was the most sensitive genotype. In all genotypes well supplied with Zn, the rate of phytosiderophore release was very low and did not exceed 1 #mol 32 plants-t 3h-1, or 0. 5/zmol g-1 root dry wt 3h-1, However, under Zn deficiency, with the onset of visual Zn deficiency symptoms, the release of phytosiderophores was enhanced in bread wheat genotypes up to 7.5 #mol 32 plants-1 3h-l, or 9/zmol g-1 root dry wt 3h-1, particularly in Zn-efficient Kirag-66, Gerek-79 and Aroona. In contrast to bread wheat genotypes, phytosiderophore release in Zn-deficient durum wheat genotypes remained at a very low rate. Among the durum wheat genotypes BDMM-19 had highest rate of phytosiderophore release. HPLC analysis of root exudates showed that U-deoxymugineic acid (DMA) is the dominating phytosiderophore released from roots of Zn-efficient genotypes. In root extracts concentration of DMA was also much higher in Zn-efficient than in inefficient genotypes. The results demonstrate that enhanced synthesis and release of phytosiderophores at deficient Zn supply is involved in Zn efficiency in wheat genotypes. It is suggested that the expression of Zn efficiency mechanism is causally related to phytosiderophore-mediated enhanced mobilization of Zn from sparingly soluble Zn pools and from adsorption sites, both in the rhizosphere and in plants.

This study was conducted in Department of Horticulture, Faculty of Agriculture, University of Cukurova in 1999 and 2000. Watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] cultivar Crimson Tide was grafted onto 10 different rootstocks. Cucurbita moschata, Cucurbita maxima and Lagenaria siceraria were open pollinated cultivars, and Strong Tosa, Gold Tosa, P360 (Cucurbita maxima × Cucurbita moschata), Skopje, Emphasis, 216 and FRG (Lagenaria spp.) were hybrid cultivars. The ungrafted Crimson Tide watermelon cultivar was used as the control. Plants were grown under low tunnel conditions until the outdoor temperature was suitable (22-25°C) for watermelon growth. Our results showed that while survival rate was low (65%) in Cucurbita type rootstocks, it was high (95%) in Lagenaria type rootstocks. Grafted plants flowered about 10 days earlier and showed more vigorous vegetative growth than the control plants. Grafted plants had up to 148% higher fresh weights than control plants. Similarly, grafted plants showed 42-180% higher dry weight, 58-100% more leaves and larger leaf area as compared with the control. In total yield, Lagenaria type rootstocks produced a higher yield but Cucurbita type rootstocks produced a lower yield than the control. While control plants had 6.43 kg/m 2 yield, Lagenaria type rootstocks produced 27-106% higher yield than the control. In contrast, Cucurbita type rootstocks had 127-240% less yield than the control. This could be attributed to incompatibility of Cucurbita rootstocks because some of the plants died before harvest. The study showed that rootstock choices influence plant growth as well as yield and quality of scion fruit, suggesting an important consideration in the potential use of grafting applications in watermelon.

Six bread wheat (Triticum aestivum cvs. Aroona, and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-l149, Kiziltan-91 and Durati) genotypes were grown under controlled environmental conditions in nutrient solution for 20 days to study the effect of varied supply of Zn (0 to 1 #M) on Zn deficiency symptoms in shoots, root and shoot dry matter production, and distribution of Zn in roots and shoots.Visual Zn deficiency symptoms, such as whitish-brown lesions on leaves, appeared rapidly and severly in durum wheats, particularly in Kiziltan-91 and Durati. Among the durum wheats, BDMM-19 was less affected by Zn deficiency, and among the bread wheats Kira~-66, ES 91-12, Aroona and Gerek-79 were less affected than ES-14 and Kirkpinar.Under Zn deficiency, shoot dry matter production was decreased in all genotypes, but more distinctly in durum wheat genotypes. Despite severe decreases in shoot growth, root growth of all genotypes was either not affected or even increased by Zn deficiency. Correspondingly, shoot/root dry weight ratios were lower in Zn-deficient than in Zn-sufficient plants, especially in durum wheat genotypes.The distinct differences among the genotypes in sensitivity to Zn deficiency were closely related with the Zn content (Zn accumulation) per shoot but not with the Zn concentration in the shoot dry matter. On average, genotypes with lesser deficiency symptoms contained about 42% more Zn per shoot than genotypes with severe deficiency symptoms. In contrast to shoots, the Zn content in roots did not differ between genotypes. Shoot/root ratios of total Zn content were therefore greater for genotypes with lesser deficiency symptoms than for genotypes with severe deficiency symptoms (i.e. all durum wheat genotypes).The results suggest that the enhanced capacity of genotypes for Zn uptake and translocation from roots to shoot meristems under deficient Zn supply might be the most important factor contributing to Zn efficiency in wheat genotypes. The results also demonstrate that under severe Zn deficiency, Zn concentration in the shoot dry matter is not a suitable parameter for distinguishing wheat genotypes in their sensitivity to Zn deficiency.

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In this study, the Turkish watermelon genetic resources were collected in 2004 and morphologically characterized in 2005. The collection comprising of traditional cultivars and local accessions were collected from 15 different provinces of Southeastern Anatolia, Aegean, Marmara-Thrace, Middle Anatolia and Mediterranean regions of Turkey where local watermelon types are widely grown. A total of 134 accessions were characterized morphologically according to UPOV descriptor list for 56 qualitative characters (6 seedling, 4 plant, 11 leaf, 5 flower, 23 fruit and 7 seed) and morphologic relatedness were examined. Additionally, 22 quantitative characters were also measured. Our results indicated that the accessions studied have a great deal of variation for most of the morphological traits. The accessions were divided into five different groups according to principle component analysis. However, the geographical origin was not a great source for grouping.

: A total of 67 watermelon accessions which include 37 accessions from Korean and 27 accessions from Turkish germplasm and 3 accessions of other related species from USA were investigated for morphological characteristics. The UPOV descriptor list for 56 characters (6 seedlings, 4 plants, 11 leaves, 5 flowers, 23 fruits and 7 seeds) was used in characterization. In addition, eight quantitative characters, hypocotyl length, cotyledon width, cotyledon length, fruit weight, fruit length, fruit width, thickness of outer layer of pericarp and soluble solid content were also measured. The 56 qualitatively scored characters were analyzed by principle coordinate analysis (PCoA) while the eight quantitative ones were subjected to principle component analysis (PCA). Morphological characterization result demonstrated that the accessions displayed high morphological diversity(how much percent?). A high level of phenotypic diversity was observed from the results of morphological characterization. However, plant growth habit and leaf blade flecking showed constant characters for all of the accessions. The Korean and Turkish watermelon genotypes are diverse groups and can be separated by both multivariate analysis of morphological characters although the grouping was more apparent in PCoS results.