Evaluation of yield and yield-related traits for waterlogging tolerance in mungbean genotypes using multivariate techniques

Waterlogging is a major constraint of mungbean production in the tropical and subtropical regions of the world and can cause a significant yield loss. The study evaluated 100 mungbean genotypes for tolerance to waterlogging employing rigorous field screening procedures. Three-week-old seedlings of 100 mungbean genotypes were subjected to waterlogging for 3 days maintaining a waterlogging depth of 2.5 cm. Waterlogging tolerance was evaluated during the periods of recovery and final harvest considering relative performance (values of waterlogging relative to non-waterlogging controls) of 18 plant traits. All the genotypes showed a wide range of variation in relative values. Some genotypes subjected to waterlogging produced plenty of adventitious roots that contributed to foliage development and chlorophyll increment, which resulted in better shoot growth, and eventually yield of mungbean increased. Nine plant traits highly associated in waterlogged conditions were used in cluster analysis. The genotypes within cluster 6 and cluster 7 performed better regarding almost all plant traits whereas cluster 4 performed very poorly. Discriminant function analysis showed that function 1 and function 2 explained 54.5% and 32.2%, respectively and altogether 86.7% variation in the genotypes. The harvest index and straw dry matter mostly explained the total variance in function 1. Dry matter of root, shoot and straw explained the maximum variance in function 2. Root dry matter played the most dominant role in explaining the maximum variance in the genotypes. The genotypes IPSA-10 and VC 6379 (23-11) showed a better degree of tolerance to waterlogging concerning yield and associated morpho-physiological traits.

Aluminum toxicity effect on the initial growth of yacon plantlets

ABSTRACT The increasing consumption of yacon potato has raised worldwide interest in its crop and generated demand for scientific elucidations of several factors associated to its agricultural management. Among the demands, there are the studies related to the effects of aluminum (Al3+) on the development of yacon plants. Thus, this study was developed to evaluate the effects of aluminum on budding and initial growth of yacon plantlets. The experiment was carried out in a completely randomized block design, with three replications and six aluminum contents in the substrate: 0, 10, 25, 50, 100, and 200 mg L-1. The response of yacon plantlets to aluminum contents was evaluated by the emergence time, emergence speed index, number of leaves, plant height, leaf area, radicle length, and dry mass weight of leaves, stems, and radicles. The presence of aluminum in the substrate negatively influences the emergence and initial growth of yacon, causing losses in foliage development (number of leaves and leaf area), in biomass accumulation, growth and, especially, restricting the development of radicles. Aluminum toxicity fully inhibits radicle growth in substrate contents above 83 mg L-1, under the controlled conditions used in this experiment.

Hydroponic Minituber Production in Growth Room Conditions and Carry-Over Effects of the Technique on Produced Minitubers

<p>The production of minitubers was implemented with a hydroponic technique in growth rooms and the carry-over effects of the technique on the characteristics of minitubers were studied. As a comparison, minitubers from in vitro plantlets were grown in a peat-based growing medium. The results show that hydroponic production of minitubers is successful in indoor conditions with the cultivars Desiree, Van Gogh and Asterix, when day-time growing temperatures of 19.4 ^oC-26.0 ^oC and night-time temperatures of 17.5 ^oC-22.6 ^oC were used. Photosynthetically active illumination was adequate at 2383-2509 umol m^-2s^-1; lighting conditions consisted of 14/10-hour day/night cycles.</p><p>The cultivars Desiree and Van Gogh developed their first tuber three weeks faster than Asterix, and the minituber yield was 4.5 per plant for Desiree, 7.5 for Van Gogh and 4.0 for Asterix. When a peat-based growing medium was used, minituber yields were almost the same but the size of the minitubers was smaller than that of hydroponically produced minitubers. The results of the carry-over experiments showed that conventionally produced minitubers emerged faster, and in terms of foliage development and yielding capacity performed better than hydroponically produced minitubers.</p>

Mulching Effects and Nitrogen Application on the Performance of Zea mays L: Crop Growth and Nutrient Accumulation

Maize is an agronomic cereal species that is sensitive to nutrient applications, especially nitrogen. Field experiments were conducted in 2011 and 2012 to evaluate the effect of nitrogen and mulching using dried weeds on maize growth and nutrient accumulation. The study was located in the Research Farm of the Agricultural Science Education Unit of the Delta State University, Abraka, Nigeria ((latitude 5046’N and longitude 605’E). The experiment consist of eight (8) treatments (i) control (ii) 40kgNha-1(iii) 80kgNha-1(iv) 120kgNha-1(v) 4.5t ha-1Panicum maximum+ 40kgNha-1(vi) 4.5t ha-1Pueraria phaseoloides+ 40kgNha-1(vii) 4.5t ha-1Eleusine indica+ 40kgNha-1(viii) 4.5t ha-1Stylosanthesgracilis+ 40kgNha-1. The treatments were replicated three times. From research results, the combination ofPueraria phaseoloideswith 40kgNha-1showed higher maize plant height, foliage development attributes, shoot dry matter, crop growth indices and nutrient uptake compared to other combinations, while only nitrogen application of 120kgNha-1recorded the highest in all the treatments. It can be concluded based on the results in this study, that legume based weeds as mulch can be supplemented with nitrogen to improve maize growth.

Growth and development of ash (Fraxinus excelsior L.) seedlings on different humus types under a closed forest canopy

In Sep. 1995, in stands with ash and oak - beech, 116 two to four-year-old ash (Fraxinus excelsior L.) seedlings were selected in 12 plots in order to assess collar diameter growth, number of leaves, branches and growth flushes (episodes) per seedling, produced during the next two years. At the same time, 30 seedlings were selected to measure the root length and the root: shoot ratio. Seedlings were growing on different levels of soil fertility (humus types of typical mull, acid mull and mull moder), under a dense canopy (2.5% light intensity). The investigation reveals that, under the high shade of the stands, the length of roots as well as root: shoot ratio is greater on more fertile sites (typical mull and acid mull), than on less fertile site (mull moder). However, the mean root length of the seedlings in this deciduous forest never reaches 9 cm, presenting a limited growth on the various humus types and a rather low stability in the thick litter layer on the mull moder humus type. There are no significant differences (P &lt; 0.05) in growth and foliage development of the seedlings produced on the different humus types. After 2 growing seasons, the mean diameter increment does not exceed 0.6 mm. The mean number of branches and leaves increases respectively with 1 and 4-5 units per seedling and that of the growth flushes varies from 2 to 3 units per seedling. As a whole under the full canopy, ash seedlings prove a very poor response to the humus types. The study suggests a proper felling in the closed canopy of the stand in order to encourage the growth and foliage development of the ash seedlings growing on the different humus types.

603 PB 217 IMPROVEMENT OF APRICOT BUDBREAK BY APPLICATION HIDROGEN CYANAMIDE

A major obstacle to economic production of deciduous fruit tree under desert conditions is an insufficient period of chilling temperatures. Inadequate chilling on apricot may result in poor and uneven budbreak, reduced and delayed foliage development, sparse bloom, poor fruit set, and/or early grown cesation, with the objective of improve budbreak, applications of Hidrogen Cyanamide (H2 C N2) were made to mature apricot `Canino' trees on January 30. Two rates of H2 C N2 and a control were evalluated for that proposal. Amount of chilling accumulated was 360 chill hours according Da Motta model. Hidrogen Cyanamide advanced budbreak 7 days at the highest rate as compared to control. Cumulative percent budbreak on March 15 were 40, 64 and 72% for o, 0.75 and 1.5% respectively. In this year, bud abscission was similar for all the treatments.

Defoliation of tamarack by outbreak populations of larch sawfly in subarctic Quebec: measuring the impact on tree growth

In conjunction with other major perturbations, outbreaks of specialist insect defoliators could play a key role in the long-term evolution of northern forest communities. Sawfly oviposition marks up to 20 years old in shoots of tamarack, Larixlaricina (Du Roi) K. Koch, provide a direct record of a large-scale epidemic cycle of the larch sawfly, Pristiphoraerichsonii (Htg.), during the 1980s in the Grande Rivière de la Baleine region, northern Quebec. Because no significant tree mortality was noted in the years following peak defoliator populations in 1985–1986, a study was undertaken to determine whether insect population changes during the outbreak period were correlated with growth changes under various climatic and soil conditions in three coastal sites and one continental sampling site. The fluctuations with time in the density of oviposition marks on trees indicated that the epidemic cycle was synchronous at all sites. However, the defoliator's density was significantly higher at the inland site, located 150 km from Hudson Bay, than at the coastal sites, where climatic conditions may be less favorable to insect activity and survival. No significant effects on tree growth were detected at the coastal sites, whereas larch from the inland site recorded a significant reduction in radial growth in 1984, the 1st year of outbreak conditions. Larch from this site also showed significant effects on foliage development after 4 years of defoliation (1988), when a virtual stop on elongative growth became apparent. Larch trees reproduced actively during the outbreak, with peak reproductive effort in 1984 and 1987 correlating with lows in elongative growth. Delayed or minimal effects of this outbreak characterized by the presence of hundreds of sawfly colonies per tree and defoliation levels comparable to those observed in the boreal forest during similar outbreaks indicate that subarctic larch may be highly tolerant to prolonged defoliation by the larch sawfly.