Grafting Helps Improve Photosynthesis and Carbohydrate Metabolism in Leaves of Muskmelon

Abstract

The most important quality for muskmelon (Cucumis melo L.) is their sweetness which is closely related to the soluble sugars content. Leaves are the main photosynthetic organs in plants and thus the source of sugar accumulation in fruits since sugars are translocated from leaves to fruits. The effects of grafting muskmelon on two different inter-specific (Cucurbita maxima×C. moschata) rootstocks was investigated with respect to photosynthesis and carbohydrate metabolism. Grafting Zhongmi1 muskmelon on RibenStrong (GR) or Shengzhen1 (GS) rootstocks increased chlorophyll a, chlorophyll b and chlorophyll a+b content and the leaf area in middle and late developmental stages of the plant compared to the ungrafted Zhongmi1 check (CK). Grafting enhanced the net photosynthesis rate, the stomatal conductance, concentration of intercellular CO2 and transpiration rate. Grafting influenced carbohydrates contents by changing carbohydrate metabolic enzymes activities which was observed as an increase in acid invertase and neutral invertase activity in the functional leaves during the early and middle developmental stages compared to CK. Grafting improved sucrose phosphate synthase and stachyose synthase activities in middle and late developmental stages, thus translocation of sugars (such as sucrose, raffinose and stachyose) in GR and GS leaves were significantly enhanced. However, compared with CK, translocation of more sugars in grafted plants did not exert feedback inhibition on photosynthesis. Our results indicate that grafting muskmelon on inter-specific rootstocks enhances photosynthesis and translocation of sugars in muskmelon leaves.

Studies of Grafts in vegetables, an alternative for agricultural production under stress conditions: Physiological responses

“…However, this decrease is up to 50% higher in plants that are not grafted and are under stress conditions due to high concentrations of NaCl; the same authors [38], found an inverse linear correlation of the photosynthetic activity with respect to the concentration of Na + and Cl-in leaves, attributing the excess of these to a disorder in the photosynthetic apparatus; similar studies witnessed the same photosynthetic activities [39,40]. Under normal conditions (without stress), grafted plants behave in a similar way to previous studies; in the case of Amaro et al [41], observed that the grafting of the cucumber plants increased the stomatal conductance and photosynthetic capacity of the plant compared to those that had not been grafted; Similar results were reported by Liu et al [42], attributing this increase in photosynthetic capacity to an increase in the amount of chlorophyll a and b in plants; additionally they reported the increase in carbohydrate accumulation in fruit, due to the activity of two key enzymes for this process in melon plants; Similar results were presented by QI et al [43] and González et al [44], in melon and citrus respectively. Likewise, Qinghai Gao et al [45], Suggest that grafted plants have the ability to better use Cl under stress conditions, as well as presenting a better photosynthetic ef iciency compared to those plants that were not grafted, this higher photosynthetic ef iciency may be due to the fact that high levels of Cl decrease the transpiration of the leaves, improving the ef iciency of water use in photosynthesis [46].…”

Performance of Grafted Seedless Watermelon Plants with and without Root Excision under Inoculation with Fusarium oxysporum f. sp. niveum Race 2

“…content (Liu et al, 2011). Although we did not measure leaf area and other growth parameters in the field experiment, our results from the greenhouse experiments suggested the improved total leaf area, root length, and root surface area might be important contributing factors to the increased fruit size of grafted watermelon in the field trial.…”

Rootstock x Environment Interactions on Nitrogen-Use Efficiency in Grafted Tomato Plants at Different Phenological Stages

“…To do this, plants require to enhance their capacity to assimilate inorganic N, which was verified in a previous study where the activity of nitrate reductase was shown to increase in tomato leaves exposed to higher light intensities [31]. Several studies in cereal crops [32][33][34] and muskmelon [35] report a positive correlation between chlorophyll content and NUtE. Our results show no changes in chlorophyll content under different NUE values, in agreement with some reports in grafted Solanaceae crops, such as tomato or bell pepper [36,37].…”