The cultivation of bush tea (Athrixia phylicoides DC.) has been shown to be affected by light availability which has encouraged the use of different net shading to filter the amount of light on the plant. The objective of this study was to enhance the levels of caffeoyl-D-glucaric acid derivatives through UV induced geometrical isomerization. Bush tea methanolic leaf extracts were placed under UV light lamp at 254 nm for the duration of 24 h and new metabolites which formed due to UV exposure were detected through ultra-high-liquid chromatography quadrupole time-of-fight mass spectrometry (UHPLC-QTOF-MS). Hydroxyl-cinnamic acids (HCAs) derivatives have been shown to undergo photoisomerization during post ultra-violet (UV) light exposure, evidenced by the emergence of photo-isomers.
We examined the effects of citric acid (CA) on organogenesis from protocorm-like bodies (PLBs) of Cymbidium floribundum to determine the appropriate concentration of CA for organogenesis. Explants were cultured in modified MS media supplemented with various concentrations of CA and maintained at 25±1℃ and a 24 h light period for 9 weeks. Addition of 0.1 g/L CA in modified MS media partially reduced the browning intensity in the cultured PLBs, which significantly increased PLB formation, shoot formation from the PLBs, and root formation from the shoots. More than 0.1 g/L CA in modified MS media increased the browning intensity in cultured PLBs. We concluded that CA can effectively control the browning problem in PLB culture of C. floribundum, and addition of 0.1 g/L CA in modified MS media was optimum for organogenesis.
Application of liquid digestate (LD), a by-product derived from anaerobic digestion of organic materials, was optimized for lettuce cultivation in closed plant production system (CPPS). LD can be dried to reduce transportation cost but ammonium, a major source of nitrogen in LD, is substantially lost during the process. In Experiment 1, it was shown that mixing of LD with lime juice at the ratio of 7:3 before drying was most effective in preventing ammonium loss. This redissolved mixture (RM) was used for fertigation in subsequent experiments. In Experiment 2, lettuce plant fertigated with RM had lower growth than those fertigated with chemical fertilizer when both treatments had the same nitrogen concentration. In Experiment 3, fertigation of RM resulted in lettuce plant with lower growth and higher accumulation of malondialdehyde than those fertigated with redissolved LD added with nitrate suggesting that growth suppression in the plant received RM could be attributed to ammonium toxicity. Reduction of light intensity causes an increasing of fresh and dry weight of lettuce plants in all treatments. Results from this study showed that RM can be used for lettuce cultivation in CPPS and condition of low light intensity with prolonged photoperiod can improve growth of lettuce plant.
Leptochloa chinensis (L.) Nees, is known as a noxious weed species in upland and lowland crop cultivation, and has naturalized in many countries as an invasive plant species. In this study, the allelopathic characteristic of L. chinensis was evaluated to understand its invasiveness. An aqueous methanol extract of the above-grand parts of L. chinensis suppressed the growth of weed species; Echinochloa crus-galli (L.) Beauv., Vulpia myuros (L.) C. C. Gmel. and Lolium multiflorum Lam., and crop plants; cress (Lepidum sativum L.), lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.). Significant reductions in the growth were observed as the extract concentration was increased. The effectiveness of the extract varied with the test plant species. The present research suggests that L. chinensis may have allelopathic characteristic and the characteristic of L. chinensis may contribute its invasiveness.
To investigate the effects of different types of irradiation on the growth and morphological characteristics of leaf lettuce (Lactuca sativa L. var. crispa “Greenwave”), a quantitative analysis of the leaf contour using an elliptic Fourier descriptor (EFD) was carried out together with conventional measurement methods. Two experiments were conducted to test the different treatments. Experiment 1 investigated the effects of monochromatic/alternating/simultaneous red/blue irradiation, and Experiment 2 determined the effects of random variations in photosynthetic photon flux density (PPFD) compared with that of constant light. The growth and morphological characteristics in Experiment 1 were consistent with those of previous studies, where the shoot fresh weights in monochromatic and alternating irradiations were larger than those in simultaneous irradiations. EFD showed that the leaf length and petiole under monochromatic and alternating irradiation were longer and more apparent than those under simultaneous irradiation. In Experiment 2, both the conventional measurement methods and EFD could hardly detect any differences in leaf lettuce growth and morphological characteristics under constant PPFD. These results suggested that fluctuating PPFD within certain limits in a PFAL may have little effect on the leaf lettuce growth.
