Leaf Clip Research Articles

Leaf Wand for Measuring Chlorophyll Fluorescence on Cylindrical Leaves and Its Application on <i>Juncus roemerianus</i> (Black Needlerush)

Chlorophyll fluorescence is a well established technique to rapidly and non-invasively determine photosynthesis parameters in plant leaves. It can be used in both laboratory and field settings, and frequently dark-adaptation of a leaf sample is called for. In the field, this can be accomplished on flat leaves using standard leaf clips supplied by instrument manufacturers. However, not all plant leaves are flat, many are cylindrical or otherwise three-dimensional in shape. The standard leaf clip does not close fully on three-dimensional leaves, therefore, does not allow the sample to be properly dark adapted in the field. A new leaf “wand” was developed that can be slipped over an entire cylindrical leaf or culm of rushes and sedges for both light- and dark-adapted measurements. This new leaf wand is compared to the standard leaf clip (DLC-8) using a Walz mini-PAM on Juncus roemerianus(Black needlerush). Results indicate that dark-adapted yield measurements are not significantly different between leaf clips, while light-adapted yields are higher with the leaf wand. The potential sources of difference in the optical path of the excitation light and fluorescence return are discussed and compared between leaf clips. Construction of specialized leaf wands should be considered for any leaves are not flat and therefore that do not fit the standard leaf clip for complete dark-adaptation under field conditions.

Effect of pre-budwood collection treatment on budding success in cocoa (Theobroma cacao L)

The inconsistencies in success of budding exercises pose great problem in the rapid multiplication of desirable genotypes for germplasm, clonal plot and seed garden establishment in cacao, Theobroma cacao L. This study was carried out at Cocoa Research Institute of Nigeria, Ibadan to determine the effects of pre-budwood collection treatments of twig on bud take and sprout. Four treatments (i) whole leaf clip (ii) half leaf clip (iii) apical bud clip and (iv) twig wounding at the point of budwood collection and (v) a control (budwood collection and budding on the same day) were applied. Budwoods were collected 2, 4, 6, 8 and 10 days after treatment (DAT) giving a factorial experiment of 5 x 5 in a randomized complete block design. Clone Na 32 was used for this experiment. Results showed that the wounding treatment gave a significantly greater (p < 0.001) bud take than all other treatments for all the days under study. At 2 – 6 DAT, there was no significant difference (p < 0.609) between the wounding treatment (68% - 82%) and the control (48% - 72%). However, at 8 – 10 DAT, bud take in the wounding treatment (76% - 88%) was significantly higher than the control (40% -56%). Assessment of sprouts and green buddings four weeks after opening showed that the wounding treatment consistently gave a significantly higher percentage (p < 0.001) budding success (46% - 72%) than the control (26% - 54%) for all the days studied. This strongly showed that the wounding treatment even at two days before budwood collection greatly increased bud take and sprouts and hence, budding success than in the conventional method. This study underscores the potential advantage of twig pre-treatment before budwood collection for increased budding success in cacao. Key words: Pre-budwood; budding success; cacao; Theobroma cacao L.; germplasm. Moor Journal of Agricultural Research Vol.4(2) 2003: 206-209

Effects of Feeding Sites on Fecundity and longevity of the Palm aphid, Ceretaphis palmae Chesquiere (Homoptera: Pemphigidae) on Young Dwarf Coconuts

The influence of feeding site preferences on-the fecundity and longevity of the palm aphid, Cerataphis palmae Ghesquiere on three dwarf coconut varieties: Malayan dwarf red (Mdr); Malayan dwarf green (Mdg); and Malayan-dwarf yellow (Mdy) was studied in a screenhouse using leaf clip on cages. Using Mdr, the fecundity of C. palmae was significantly highest on young’ basal leaflets followed by mature basal leaflets and young frond terminal leaflets. With the Mdg, mean number of nymphs produced on young basal leaflets and young frond terminal leaflets was significantly higher than on mature basal leaflets. Similarly, there was no significant difference in fecundity on young basal leaflets and frond terminal leaflets of Mdy variety. Fecundity on mature basal leaflets was however, lower than on both young basal and frond terminal leaflets. On the three varieties, longevity on young basal and frond terminal leaflets were significantly higher than on mature basal leaflets

Determination of the quantum efficiency of photosystem II and of non-photochemical quenching of chlorophyll fluorescence in the field.

A newly developed portable chlorophyll fluorometer in combination with a special leaf clip holder was used for assessing photosynthetic activity of attached sun leaves of Fagus sylvatica and Cucurbita pepo under field conditions. During diurnal time courses, fluorescence yield, photosynthetic photon flux density (PPFD) incident on the leaf plane, and leaf temperature were measured and quantum efficiency of photosystem II (PS II), apparent relative electron transport rates, and non-photochemical fluorescence quenching (NPQ) calculated. In both species, quantum efficiency followed closely the incident PPFD and no hysteresis could be observed during the day. Apparent electron transport rate showed light saturation above a PPFD of 700 μmol m-2 s-1 in F. sylvatica, while in C. pepo no saturation was visible up to 1400 μmol m-2 s-1. NPQ was closely correlated to excessive PPFD calculated from the PS II quantum yield. Maximal NPQ observed was 3.3 Although the beech leaf was exposed for a considerable time to PPFD values of 1400-1500 μmol m-2 s-1 and leaf temperatures between 30 and 35°C, no obvious signs for sustained photodamage could be observed. The data demonstrate the potential of chlorophyll fluorescence measurements to analyse photosynthetic performance under field conditions with minimal disturbance of the plant. Potential error sources due to the geometry of the leaf clip holder used are discussed.