The behaviour of adult Sitona lepidus Gyllenhal (Coleoptera Curculionidae) in response to white clover

Individual adult Sitona lepidus were given the choice between damaged or undamaged seedlings mature plants of white clover damp soil or a blank in laboratory experiments carried out in a simple olfactometer Adult weevils displayed five different behavioural responses two of which head lifting and antennal movement appeared to be associated with host location In choice tests 7484 of adults chose a white clover plant over the blank or damp soil When given a choice 72 of adults selected white clover seedlings over mature plants Root and leaf damage did not affect response of S lepidus to white clover seedlings

Anthocyanin regulatory gene expression in transgenic white clover can result in an altered pattern of pigmentation

This study presents the first evidence of heterologous anthocyanin regulatory genes altering anthocyanin expression in stably transformed leguminous plants. Two families of anthocyanin regulatory genes, myc (delila, B-Peru) and myb (myb.Ph2, C1), are involved in the activation of the phenylpropanoid pathway. White clover (Trifolium repens cv. Haifa) plants were transformed with dicotyledonous and monocotyledonous myb or myc genes. Some of these transformed plants exhibited enhanced anthocyanin accumulation in a range of tissues. One plant, transformed with the B-Peru gene driven by the Cauliflower Mosaic Virus 35S promoter, displayed a unique pattern of anthocyanin accumulation in the leaf. The accumulation of anthocyanin in this plant was closely associated with the crescent of leaves, which is normally white. The red pigmentation declined in intensity in the oldest leaf stage. The B-Peru message was detected in all leaf stages of this white clover plant. This anthocyanin pattern was shown to be heritable.

White clover plant morphology in Waikato dairy pastures

Seasonal changes in white clover plant morphology were investigated in Waikato dairy pasture. Plants were classified according to the degree of branching, 2nd-order plants comprising the bulk of the population (47%) throughout the year. There was a slightly greater proportion of lst-order plants than found in similar studies on sheep-grazed swards in Manawahr. Plant fragmentation occurred in late spring, increasing the proportion of lstorder plants. A corresponding decrease in plant size was observed, with minimum values measured for most characteristics, i.e., stolon, leaf and root dry weight (DW); stolon length, and number of leaves, roots and growing points. Overall, white clover plants in Waikato dairy pastures are considerably larger than plants in Manawatu sheep pastures. The trial highlighted that because white clover plants in spring are small, they are vulnerable to mismanagement in dairy pastures, just as has been demonstrated in pasture grazed by sheep. There were, however, some significant differences in white clover plant structure in dairy pastures compared with sheep-grazed swards. Keywords: dairy pasture, morphology, plant order, plant size, seasonal variation, Trifolium repens

White clover soil seed loads: effect on requirements and resultant success of cultivar-change crops

A study was done at Canterbury Agriculture and Science Centre, Lincoln, New Zealand, to equate volunteer white clover plant establishment with the decay of the soil seed burden over time. A 5 season break without clover sowings, if coupled with either annual cultivation or herbicide removal of establishing volunteer plants, reduced contamination potential below that desired to meet certification requirements for first-generation seed crops. 'Buried-seed counts' taken after the last deep cultivation for the change crop should be in the O-3 seeds per 50 cores range for breeders' and basic crops and 4-6 per 50 cores for first-generation crops. Sowings to produce breeders' and basic seed must be in 45-cm row spacings to facilitate inter-row herbicide elimination of volunteers. Ministry of Agriculture and Fisheries Seed Testing Station data on 705 potential change crop sites over 5 seasons, indicated that for breeders basic and first generation, only 31% and 50% of paddocks respectively fell within these ranges, justifying the continued use of this measure as an indicator of potential for success. For the 1989-90 season, 17% of the 182 first-year autumn-sown cultivar-change certification entries were withdrawn because of poor establishment and/or weed problems, 3% for wrong sowing methods obviating inspection a n d 5 % w e r e r e j e c t e d b e c a u s e o f contamination. Currently, the major limitation to growing high yielding white clover change crops, particularly of small-leaved cultivars, is in making seed multipliers aware of available technology. Keywords: white clover, contamination, buried seed, volunteer plants, certification

CLOVER - WHAT TYPES FOR DRY HILL COUNTRY?

Subterranean clover and white clover plant material was collected from 85 sites located in summerdry northern North Island hill country. Plants of both species originating from this collection were grown and typed at Whatwhata Hill Country Research Station. Using several cultivars and selections as standards, measurements were made of morphological, flowering and reseeding characteristics. The subterranean clover population consisted of 44% Mt Barker type, 28% Tallarook type and the remainder an undetermined intermediate type. Mt Barker types in the collection tended to flower later and for longer than their Mt Barker standard, while Tallarook types tended to flower earlier and for longer than StandardTallarook. White clover plants were smaller and more densely leaved than 'Grasslands Huia', the population mean being similar to 'Grasslands Tahora'. A vast majority (7035%) of plants flowered earlier and yielded more seed than Huia and Tahora. An apparent shift in plant type has occurred within clover populations in summerdry hill country, the most notable being the development of a more flexible reseeding pattern. This type can be a future guide to breeding clovers suitable to these environment . Keywords: white clover, subterranean clover, flowering, seeding, morphology, type hill country

Growth of the white clover plant in relation to seed production

The growth and development at the stolen apex of white clover is described, particularly in relation to inflorescence initiation, and the factors controlling such initiation are reviewed for the range of cultivars which has been studied. The difference between the responses to environment in plants of Mediterranean and high latitude origin are emphasized. Key words: Trifolium repens, growth, flowering, photoperiod, temperature, seed production.

The release of phosphorus from plant material added to soil

An experiment was conducted to study the release of 32P from white clover plant residues in the presence and absence of growing oats plants in both low and high phosphorus status soils. Net reutilization of phosphorus from the added plant material after 48 days was highest in the high phosphorus system in the presence of plants (29.3 %) and least in the low phosphorus system in the absence of plants (0.6%). Watering to field capacity daily, every 3 days, or every 6 days, had no significant effect on reutilization rates. Evidence from the soil inorganic phosphorus data suggests that the addition of plant material resulted in a significant immobilization of soil phosphorus only in the low phosphorus soil in the absence of plants. The significance of these findings is discussed in relation to the large number of incubation studies conducted to study phosphorus turnover rates in soil.