Reproductive Development of <i>Lotus tenuis</i> (Fabaceae) Crop Defoliated at Different Times and Intensities

Abstract

Lotus tenuis forage yield has been quantified under defoliation conditions in pastures, grasslands and under dual-purpose production of both livestock forage and seeds. However, little is known about the effects of defoliation management on L. tenuis flower and pod production and subsequent seed yield. Two field experiments were conducted to study the response of L. tenuis to defoliation at different flowering stages and intensities. In Experiment 1, crops were defoliated at the beginning of the flowering (DBF), mid-flowering (DMF) or full flowering (DFF). In Experiment 2, defoliation was in vegetative stage at low (LDI) or high (HDI) intensities. Defoliation in Experiment 1 neither affected plant cover nor the photosynthetically active radiation intercepted by the crop during pod production. There were less umbels with dehiscent (shattered) pods in the DFF treatment than in Control, DBF and DMF treatments. Flower peak occurred first in the Control, DBF and DMF treatments, and eight days later in DFF plots, however, seed yield was not affected (1324 ± 32.8 kg·ha −1 ). Defoliation intensity did not affect seed yield (962 ± 25.9 kg•ha − 1 ) because of self-compensation which increased harvest index in HDI (14.5% ± 0.6%) compared to the Control and LDI (12.0% ± 0.3%) treatments. Plant survival was not affected by defoliation treatments in any of the experiments. Flowering can be synchronized through defoliation. The blooming of large numbers of flowers in a short time was achieved, reducing the number of shattered pods. Compensatory responses through plant plasticity conferred L. tenuis the ability to overcome defoliation without affecting seed yield. Lotus tenuis defoliation as management tool will be considered in future researches because it is possible to harvest forage and to increase seed yield through a reduction of shattered pods. O. R. Vignolio et al.

EFFECTS OF TEMPERATURE, PHOTOPERIOD AND DEFOLIATION ON FLOWERING TIME OF LOTUS TENUIS (FABACEAE) IN BUENOS AIRES, ARGENTINA

“…Accumulated growing degree-days (AGDD) for of Lotus tenuis plants defoliated at different intensities and recorded at different phenological phase. Treatments were an uncut Control, a low (LDI) or high (HDI) defoliation intensity (Vignolio et al, 2016). Reference: seedling emergence, S. E. Parameters b 3 and c 3 in the photothermal model used in this study were positive.…”

“…Crop defoliation data were obtained from plants defoliated at vegetative stage (Vingolio et al , 2010). Two defoliation intensities were applied low (LDI) and high (HDI), reducing crop height by 54 and 75% compared to plant height before defoliation, respectively (Vignolio et al , 2016). Figure 1 synthetizes seedling emergence date, flowering time, photoperiod, air temperature, two defoliation events, data sources and L. tenuis cultivars.…”

“…Forage legumes of genus Lotus are of great interest for sustainable production of agricultural systems. Lotus tenuis, L. corniculatus and L. pedunculatus are extensively used as forage in many temperate grasslands and pastures of different countries (Blumenthal and McGraw, 1999;Escaray et al, 2012;Fairey and Smith, 1999;Vignolio et al, 2016). These species have economic potential because they fix atmospheric nitrogen via symbiosis, improve soil fertility, optimize the forage quality of pasture and grasslands have high nutritive value and voluntary feed intake of beef cattle (Blumenthal and McGraw, 1999;Escaray et al, 2012;Vignolio et al, 2016).…”

“…Although flowering time is considered critical for plant reproduction, little is known about the effects of sowing date and defoliation on L. tenuis reproductive phase (Vignolio et al , 2006; 2010; 2016). Lotus tenuis flowers time can be affected by defoliation (Vignolio et al , 2006; 2010; 2016). Lotus tenuis and L. corniculatus flowering can be synchronized through defoliation; a flush of large numbers of flowers in a short time determines a more uniform seed ripening (Vignolio et al , 2016).…”

“…Lotus tenuis flowers time can be affected by defoliation (Vignolio et al , 2006; 2010; 2016). Lotus tenuis and L. corniculatus flowering can be synchronized through defoliation; a flush of large numbers of flowers in a short time determines a more uniform seed ripening (Vignolio et al , 2016). However, if most flowers and pods are produced in a shorter time, this can produce abort of these organs, because competition by assimilates increases (Egli and Bruening, 2006).…”