Persistence of the yield advantage of perennial ryegrass cultivars: concept, evidence and implications

Pasture persistence can be defined several ways, but a key outcome for farmers is that the yield advantage of a new pasture compared to the pasture it replaced persists for several years after sowing. The concept of persistence of the yield advantage can also be applied to genetic evaluation of cultivars in species such as perennial ryegrass to determine the true value of pasture renewal and cultivar selection. We analysed 8 years of yield and tiller density data from pastures sown to four perennial ryegrass cultivars representing different functional types at two locations, Waikato (non-irrigated) and Canterbury (irrigated). ‘Grasslands Nui’ SE (Nui) was designated as the baseline cultivar. A significant yield advantage over Nui was observed for two cultivars (Alto AR37 and Halo AR37). Peak yield advantage occurred 4 or 5 years post-sowing, then declined by approximately 50% and became nonsignificant by Year 8. The pattern was very similar at both locations. Tiller density data indicated a shift in sward structure over time consistent with size-density trade-offs in the diploid cultivar Alto AR37 but not in the tetraploid cultivar Halo AR37. The implications for economic evaluation systems such as the DairyNZ Forage Value Index are discussed.

Effect of Salt Stress on Some Physio-Biochemical Traits and Antioxidative Enzymes of Two Brassica Species Under Callus Culture

The changes in lipid peroxidation, H2O2, proline, protein and the involvement of the different antioxidant system (catalase, gayacoule peroxidase, ascorbate peroxidase) and callus-related traits were investigated in relation to salt stress in the callus of two different ploidy levels of Brassica including B. juncea and B. oleracea. The calluses of B. juncea genotypes were less sensitive to NaCl stress than that of B. oleraceae by increasing concentrations of NaCl from 0 to 200 mM.Tetraploid genotype (B. juncea cr3356) showed significant increase in the contents of protein and proline, and also activity of giacle peroxidase and catalase enzymes at higher salinity levels. Also, a significant decrease in the amount of H2O2 and malondialdehyde occurred with increasing the salinity intensity. Diploid cultivar (B. oleracea bra 2828) had the lowest enzymatic activities and the highest content of H2O2 and malondialdehyde with an increase in the salinity level. Therefore, this genotype was identified as the most sensitive cultivar to the salinity stress. The difference in the salinity resistance between diploid and amphidiploid species may be due to differences in the ploidy level of these species. This result suggests that tetraploid genome of B. oleraceae could be considered as a suitable candidate for production under salinity conditions by maintaining higher activities of antioxidant enzymes.

Effects of Cultivar, Nitrogen Rate and Harvest Time on the Content of Carbohydrates and Protein in the Biomass of Perennial Ryegrass

The aim of this study was to determine the effects of cultivar, nitrogen (N) rate and harvest time on the content of water-soluble carbohydrates (WSC), crude protein (CP) and the WSC:CP ratio in the aboveground biomass of perennial ryegrass (Lolium perenne L.). A small-area field experiment was conducted in the Agricultural Experiment Station in Tomaszkowo (53°42′40.8″ N 20°26′04.7″ E, north-eastern Poland). Data were presented for three years of full utilization (2013–2015). The experimental factors were as follows: (i) perennial ryegrass cultivar: Bajka and Baronka, (ii) N rate (kg ha−1): 0, 120, and 240, and (iii) harvest time: 8.00–10.00 a.m., 12.00–2.00 p.m., and 4.00–6.00 p.m. The tetraploid cultivar Baronka had higher WSC content and lower CP content on a dry matter (DM) basis than the diploid cultivar Bajka (by approx. 3% on average). An increase in N fertilizer rate to 240 kg ha−1 contributed to a decrease in WSC concentrations by 23% in cv. Bajka and by 19% in cv. Baronka, and to an increase in the CP content of aboveground biomass by 32% and 23%, respectively. Both cultivars accumulated significantly higher WSC amounts when biomass was harvested at noon and in the afternoon than in the morning. The CP content of biomass was also affected by harvest time, and it was higher in cv. Bajka when harvesting was carried out at 12.00–2.00 p.m. and 4.00–6.00 p.m., and in cv. Baronka when harvesting was carried out at 4.00–6.00 p.m. The WSC:CP ratio in the biomass of the analyzed cultivars was within the optimal range for ruminants, and it was higher in cv. Baronka (1:1.11). Nitrogen applied at 240 kg ha−1 had a negative influence on the WSC:CP ratio, decreasing its value by around 36% (relative to the rate of 120 kg N ha−1) and around 35% (relative to the unfertilized treatment). In both perennial ryegrass cultivars, biomass harvested in the morning was characterized by the lowest WSC:CP ratio.

Functionality of Embryo Sacs in Pear Cultivars ‘Ingeborg’ and ‘Celina’ as Related to Fruit Set under Nordic Climate

Since the European pear (Pyrus communis L.) is a self-incompatible fruit species, synchrony and compatibility between female parts of the mother plant and male gametes from the pollen donor must be fulfilled. Besides pollination and fertilization, normal embryo and zygote development is one of the prerequisites for the satisfactory yields in pears. The main goal of this experiment was to investigate the functionality of embryo sacs and the embryo’s early stages of growth in relation to the fruit set of diploid (‘Celina’) and the triploid (‘Ingeborg’) pear cultivars under specific Norwegian climatic conditions. For this purpose, flowers were collected at the beginning of flowering, and on the third, sixth, ninth, and twelfth days after the beginning of this phenophase for two consecutive years. Ovaries were dehydrated, embedded in paraffin wax, sectioned, stained, and observed under the light microscope. In the analyzed cultivars, results showed different tendencies in embryo sac development and degradation processes, in both experimental years, which is probably due to the genetic background of the examined cultivars. Also, fertilization success and fruit set were higher in the second year of study due to the higher average temperature during the flowering period. Diploid cultivar ‘Celina’ showed much better adaptation to high temperatures in relation to triploid cultivar ‘Ingeborg’.

Does time of protective procedure and genotype of chamomile affect yield?

SummaryObjective: Chamomile plants (Chamomilla recutita L. Rausch) are often attacked by pests, which usually cause the decrease of raw material yield and its quality. The objects of field trial were two chamomile cultivars: Złoty Łan (4n) and Promyk (2n) cultivated under organic regime. The aim of this study was to evaluate of impact of the spinosad treatment and its time of application on two chamomile cultivars: cv. Promyk – 2n and cv. Złoty Łan – 4n exposed to insect pests.Methods: The first treatment with spinosad as a preventative control (P) was performed in the early phase of plant development (seven leaves). Intervention (I) treatment was made in green bud phase. In both terms of observation insect pests were observed and collected. In each spraying application of 0.06 g of spinosad per 1 liter of water was used.Results: Spinosad was able to limit the number of pest population and finally increased yielding of the treated cultivars as compared to the untreated plants. Time of spinosad application for cv. Złoty Łan plants was not statistically siginificant, although was more effective for the preventative treatment of cv. Promyk in the increasing of the plant biomass (283.8 g · m−2) and seed (32 g · m−2) yields than intervention.Conclusion: Protection treatment with spinosad might be recommended in chamomile cultivation and it is more effective than intervention in diploid cultivar which begin blooming earlier than tetraploid. Essential oil content was not related with protection treatment for diploid cultivar, although intervention in tetraploid cultivar caused higher content of oil.

Changes in Morphological Characteristics, Regeneration Ability, and Polysaccharide Content in Tetraploid Dendrobium officinale

Dendrobium officinale Kimura et Migo is a famous traditional Chinese medicinal plant. It produces various phytochemicals, particularly polysaccharides, which have nutraceutical and pharmaceutical values. To increase its biomass production and polysaccharide content, our breeding program has generated a series of polyploid cultivars through colchicine treatment of protocorm-like bodies (PLBs). The present study compared two tetraploid cultivars, 201-1-T1 and 201-1-T2, with their diploid parental cultivar, 201-1, in an established in vitro culture system. Tetraploid ‘201-1-T1’ and ‘201-1-T2’ had shorter leaves and shorter and thicker stems and roots, and they produced higher biomass compared with the diploid cultivar. The length and width of stomata significantly increased, but stomatal density decreased in tetraploid cultivars. The PLB induction rates from the stem node explants of the tetraploid cultivars were significantly higher than those of diploid. However, the PLB proliferation of tetraploids was lower than that of the diploid. The mean number of plantlets regenerated from tetraploid PLBs was also lower than that of the diploid after 4 months of culture. Polysaccharide contents in stems, leaves, and roots of 6-month-old tetraploid plantlets were significantly higher than those of diploids. The polysaccharide content in the stem of ‘201-1-T1’ was 12.70%, which was a 2-fold increase compared with the diploid cultivar. Our results showed that chromosome doubling could be a viable way of improving D. officinale in biomass and polysaccharide production.

KARAKTERISASI PISANG REJANG TETRAPLOID HASIL INDUKSI DENGAN ORYZALIN

Triploid banana cultivar is the most desirable cultivar in banana industry because of its higher yield compared to its diploid cultivar. The triploid cultivar can be produced by crossing tetraploid with diploid cultivar. However, tetraploid banana cultivar is rarely existed naturally. Induced tetraploid of Pisang Rejang was produced using oryzalin. The present research was conducted to characterize tetraploid Pisang Rejang (Musa acuminata, AAAA genome) induced by in-vitro oryzalin treatment from diploid Pisang Rejang. Ploidy level, molecular and morphotaxonomic characters were observed. Ploidy identification of induced Pisang Rejang was conducted using Flowcytometer. Molecular characterization was done using RAPD and ISSR markers. Morphology characters were observed based on UPOV (2010). The results showed that tetraploid plants have similar genetic properties with their diploid controls as shown by genetic identity of 0.9901 – 0.9935. The tetraploids were differed from their diploid plants in plan habit and diameter of fruit. The tetraploid plants produce fewer suckers, drooping leaves and broader fruits compared to its diploid control.

Production of Triploid Hydrangea macrophylla via Unreduced Gamete Breeding

Hydrangea macrophylla (Thunb.) Ser., florist’s or bigleaf hydrangea, is the most economically important member of the Hydrangea genus, which accounted for over $120,000,000 in U.S. nursery sales in 2014. Both diploid and triploid H. macrophylla cultivars exist and there is some evidence that triploidy leads to larger plant and floral structures. The diploid cultivar, H. macrophylla ‘Trophee’, was previously shown to have a bimodal pollen size distribution which may be indicative of unreduced gametes. We used H. macrophylla ‘Trophee’ as a parent in a series of crosses with other diploid H. macrophylla cultivars. The objective of this study was to evaluate reciprocal full-sibling H. macrophylla families for ploidy and phenotype, determine the impact of ploidy on phenotype, and determine the efficacy of unreduced gamete breeding. Diploids and triploids were found in the offspring pool with mean 2C genome sizes of 4.5 and 6.7 pg, respectively. All offspring from crosses with ‘Trophee’ as the female parent were diploid as expected. The full-sibling family with ‘Trophee’ as the male parent contained 94% triploids, supporting the hypothesis that the bimodal pollen size distribution of ‘Trophee’ reflects the presence of unreduced male gametes. Triploids had fewer, wider inflorescences than diploids. The stems of triploids were 16% thicker and their leaves were 20% larger than those of diploid full and half-siblings. Triploids had significantly larger stomata (9.0 μm2) than diploids (5.9 μm2). These results establish a link between ploidy and phenotype in plants of similar genetic background and support the efficacy of unreduced gametes in polyploidy breeding.