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Triploid watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai) Arka Manik cultures exhibited a general pale color and yellowing of lower leaves by 3±4 wk following subculturing to fresh medium. Protecting the medium from light by covering the surface with sterile aluminum foil significantly improved leaf color and chlorophyll content by 50±60%. Raising the concentration of FeNa 2 EDTA (Fe-EDTA) in the light-exposed medium from the normal level (100 mM) to 150 or 200 mM significantly increased the leaf chlorophyll two-to threefold, suggesting that the light-induced effect was mainly attributable to photo-oxidation of Fe-EDTA. Fe-EDTA supplementation also resulted in better expansion and lobe formation of upper leaves, a reduction in internode length, an increase in the number of nodes, and a significant improvement in propagation rate. There was also a reduction in axillary sprout growth at elevated Fe-EDTA levels, indicating a more prominent apical dominance effect and a reduction in the number and vigor of tendrils. Increasing the Fe-EDTA level in the medium to 150 mM is suggested for routine micropropagation of triploid watermelon, in order to compensate for the photo-oxidative loss of Fe-EDTA.

Thirteen chickpea (Cicer arietinum L.) genotypes, raised in the field, were screened for carbon exchange rate (CER), related leaf characters and dry matter production throughout the season. Seasonal pattern of the CER and related characters were similar in all genotypes. CER showed two peaks, one at the late vegetative phase and the other at the peak pod filling phase. Stomatal resistance (rs) and specific leaf mass (SLM) increased in the successively formed leaves while nitrogen concentration tended to decline, especially in later-formed leaves. Nitrogen (N) content per unit area, however, remained relatively constant throughout the season. Significant genotypic variabilities were observed in CER and related characters as well as in total dry matter accumulated at harvest. Seasonal means of CER ranged from 12.5 in HG 1765B to 18.4 μmol CO2 m-2 s-1 in BG 315, SLM from 5.1 in HG 1765 to 6.5 mg dry weight cm-2 in BG 315, rs from 1.31 in BG 315 to 1.92 s cm-1 in Hyb 16-3, leaf N content from 122.6 in HG 1765B to 172.1 mmol m-2 in BG 315 and total dry matter at final harvest from 9.9 in HG 17658 to 34.9 g plant-1 in K4. Seasonal means of CER were positively correlated with SLM, N content per unit area and final harvest dry matter. Stomatal resistance was negatively correlated with CER and final harvest dry matter. The results indicate that although CER is the best selection criterion for higher dry matter production in chickpea, it is possible to use SLM as an indirect selection criterion for CER in this crop. However, such a selection based on SLM involves the risk of elimination of high N-use efficiency genotypes.