Fortified cassava peel compost amendment for Amaranthus: Influence on plant growth,nutrients uptake and on soil nutrient changes

Nutrient supply through organic sources usually requires fortification for timely and optimum release of plant nutrients to achieve optimum crop performance. A pot experiment was conducted in a screen house to determine the optimum rate of cassava peel compost (CPC) fortification that supports optimum Amaranthus (Amaranthus cruentus L.) plant nutrient contents and residual soil nutrient contents. A compost of cassava peel and poultry manure was applied at 2.5; 5.0 and 7.5 t ha^?1each complemented with either 25 or 50 kg nitrogen (N), using nitrogen, phosphorus and potassium (NPK) 20-10-10 at 2 weeks before sowing Amaranthus. An unfertilized treatment served as control. Seeds were sown in plastic containers with a surface diameter of 24 cm filled with 5 kg soil, with a drain underneath. Seedlings were thinned to 4 plants/pot 2 weeks after planting. Plants were harvested at 5 weeks by ratooning and plant re-growth also harvested after 5 weeks. Soil pH was lower with high rates of 5.0 and 7.5 t ha^?1 CPC while the organic matter content was increased with increased CPC rate. Soil N was reduced but reflected in increased plant shoot and root N, with compost application. Soil P was generally increased but was not reflected in plant contents. Soil K contents were reduced and were reflected in increased plant contents. Application of 2.5 t ha^?1 CPC, fortified with either 25 or 50 kg N ha^?1 gave the optimum Amaranthus shoot nutrient contents with optimum residual soil nutrient contents.     

Effect of herbicide and cover crop on weed control in no-tillage jack-o-lantern pumpkin (Cucurbita pepo L.) production

Field experiments were conducted to evaluate cover crop (none, winter wheat, or winter rye) and pre-emergence (PRE) applications of clomazone plus ethalfluralin alone or with halosulfuron [PRE or post-emergence (POST)] for smooth crabgrass [Digitaria ischaemum (Schreb. ex Schweig) Schreb. ex Muhl.] and redroot pigweed (Amaranthus retroflexus L.) control in no-tillage ‘Aspen’ jack-o-lantern pumpkin (Cucurbita pepo L.). At pumpkin harvest, cover crops had reduced smooth crabgrass density, but not redroot pigweed. Although PRE or POST applications of halosulfuron alone were more effective at reducing redroot pigweed density than clomazone plus ethalfluralin PRE, the combination of halosulfuron plus clomazone and ethalfluralin PRE reduced redroot pigweed density to the greatest extent. Pumpkin yields were not affected by cover crop, although average pumpkin sizes were greater with the inclusion of cover crop residues. Pumpkin fruit sizes and yields were the greatest with clomazone and ethalfluralin PRE in combination with halosulfuron applied PRE or POST. Overall, cover crop had relatively little influence on pumpkin yields compared with herbicide treatments. The addition of halosulfuron to clomazone and ethalfluralin provided greater broadleaf weed control resulting in greater jack-o-lantern pumpkin yields.     

Agrobacterium × plant factors influencing transformation of ‘Joseph's coat’ (Amaranthus tricolor L.)

A protocol is developed for Agrobacterium-mediated genetic transformation of Amaranthus tricolor via explant co-cultivation with Agrobacterium rhizogenes. Bacteria-plant specific factors which influenced transformation were optimized. Of the two Agrobacterium strains employed, LBA9402 was more infectious compared to A4. Bacterial suspensions grown overnight with 100 μM acetosyringone and experiencing O.D.₆₆₀ = 0.6 followed by dilution to a density of 10⁹ cells ml⁻¹ were the most effective. Explants from garden-grown plants were more responsive than those from in vitro cultures; stem internodes being better than leaves. Immersion of the pre-pricked explants in bacterial suspension resulted in a markedly higher transformation frequency compared to the direct injection method. The infection of internode explants with the LBA9402 strain followed by co-cultivation on growth regulator-free MS medium (MS0) for 5 days resulted in emergence of hairy roots up to a maximum frequency of 97.22%. Roots were individually cultured in MS0, but fortified with bactericidal antibiotic (500 μg ml⁻¹ cefotaxime). Rhizoclones showing prolific growth were renewed through successive subcultures in MS0. Opine gene expression was revealed by positive agropine and mannopine synthesis in all selected transformed rhizoclones. Shoot regeneration from root clones, capable of auxin-independent growth and opine proficiency, was stimulated in MS augmented with 2.0 mg l⁻¹ zeatin. pRi TL–DNA rolB and pRi TR–DNA man2 ORF were detected in leaf tissues of regenerated plants from selected hairy root clones through PCR amplification. The implication of such findings is discussed on the possibility of conferring protection to crop amaranths against biotic stress challenges, particularly due to insects, viruses or fungal pathogens.     

苋菜AtGAI基因密码子偏好性与进化分析

为明确苋菜AtGAI基因密码子的使用特性,采用CodonW、SPSS软件及EMBOSS在线程序分析苋菜AtGAI基因密码子的偏好性,通过中性绘图、ENc绘图和偏倚分析GAI基因密码子偏好性形成的可能原因。结果表明:1)苋菜AtGAI基因的有效密码子数(ENc)、密码子适应指数(CAI)和GC含量分别为50.75、0.195和41.91%,表明其密码子偏好性较弱,偏好使用A/T结尾的密码子;2)CDS序列及RSCU聚类分析表明,苋菜AtGAI基因与双子叶植物中石竹目含甜菜色素的植物偏好性最相近;3)密码子碱基成分和相关性分析发现,GAI基因的密码子偏好性主要受碱基突变的影响;4)密码子使用频率比较分析发现,酵母真核表达系统更适合苋菜AtGAI异源表达,模式植物拟南芥、烟草、番茄和甜菜均可做为苋菜AtGAI基因的遗传转化受体,其中甜菜是其最理想的遗传转化受体。突变压力是GAI基因密码子偏好性形成的主要因素,苋菜AtGAI基因外源表达和遗传转化时需要根据宿主基因偏好性进行密码子优化和改造。     

Plastic responses to clipping in two species of Amaranthus from the Sierra Norte de Puebla, Mexico

This study investigates the plastic responses after shoot removal of Amaranthus cruentus L. and A. hypochondriacus L. This practice is common in the Sierra Norte de Puebla, Mexico, where both species are cultivated and used as a food source during the vegetative stage. Empirical observations indicate that biomass increases in clipped plants. The experimental study carried out on both species of Amaranthus imitated local farm management. Three levels of shoot removal were applied to plants of both species: Control, 10% and 40%. In A. cruentus plants with 10% of the shoot removed produced more stalk biomass, more leaves, greater leaf area, greater length of primary branches and a larger number of secondary branches than the control plants. In A. hypochondriacus, there were no differences among levels of shoot removal in stem biomass; in general, the number of primary and secondary branches in control plants was greater than that in clipped plants. Patterns of biomass allocation revealed important differences between species, as clipped plants allocated more biomass to seeds in A. cruentus, while control plants allocated more to leaves in A. hypochondriacus. Furthermore, changes in response at the primary branch (secondary branches, leaf biomass, and area) level were observed between species. In general, clipped plants of A. cruentus overcompensate for the damage, while this response was not evident in clipped plants of A. hypochondriacus. Instead, this species showed high tolerance to damage. The phenotypically plastic responses expressed for both species can be used as a guide to improve management of these plants by local farmers from the Sierra.     

The effect of processing on total organic acids content and mineral availability of simulated cassava-vegetable diets

Changes in pH, titratable acidity and mineral content (Ca, Fe, Mg, Zn) were estimated in processed cassava products while the mineral content of raw and blanched amaranthus vegetable was determined. pH of fresh cassava (6.5) decreased as total organic acid (0.07%) increased with fermentation period. Fufu and lafun had the lowest pH and the highest total organic acids contents. Fermentation of cassava increased the total calcium and iron contents, reduced magnesium level while zinc remained fairly constant in grated cassava but was reduced when soaked in water (for the preparation of fufu and lafun). Fermentation also increased the availability of these selected minerals in both cassva products and simulated cassava-vegetable diets. Blanching reduced the mineral content of amaranthus vegetable but increased mineral availability. Fermentation of cassava and blanching of vegetables play an important role in making minerals more available and these processing methods should be encouraged to potentially ameliorate the disease states associated with mineral deficiency.     

Fitness effects of the triazine resistance mutation in Amaranthus hybridus: relative fitness in maize and soyabean crops

Fitness costs of the triazine resistance mutation were estimated in experimental populations of Amaranthus hybridus L. from Maryland and Virginia (USA). Estimated costs were attributed directly to effects of the resistance mutation, through comparisons of lines bearing similar nuclear genomes, but either resistant or susceptible cytoplasm. Experimental weed plants were established from seed in the field at a wide range of A. hybridus and crop (maize or soyabean) densities, and experiments were repeated over 3 years. Resistant cytoplasm caused large reductions in several components of fitness, but substantial differences were observed among years in these fitness costs of resistance. For the fitness component of total biomass above-ground biomass production, relative fitnesses of resistant genotypes (resistant/susceptible ratios) ranged between 0.42 and 0.70. Costs of resistance were similar in weeds growing with either maize or soyabean crops. Certain costs of resistance differed between populations: impairment of seedling establishment and early growth by the resistance mutation was evident in the Virginia population, but not in the Maryland population. This functional difference between populations was associated with greater costs of resistance in the Virginia population with respect to mid-season leaf number and total above-ground biomass production; however, only the former population difference in fitness cost was statistically significant.     

美国籽粒苋在乐都川水地区的性状表现

观察美国粒苋ＮＯ．１，ＮＯ．２，ＮＯ．３在乐都川水地区的表现性状。结果表明：ＮＯ．１和ＮＯ．３的鲜草产量分别为１３６ ６７３ｋｇ／ｈｍ＾２，１２３３３９ｋｇ／ｈｍ＾２，茎叶比为１∶０．８４，鲜干比为７．８∶１基本保持了原有的性状，可在我省川水地区推广；ＮＯ．２产量较低。     

16种园林植物不同器官的化感活性

【研究目的】 测定16种园林植物不同器官对受体植物生菜和反枝苋的化感活性；【方法】琼脂混粉法；【结果】在10 g?L-1的粉末添加浓度下，所有的供试植物器官粉末均对两种受体植物幼苗的生长产生了明显的抑制作用，且对胚根生长的抑制明显高于对胚轴生长的抑制。其中观赏桃的茎、桑树的根、紫叶小蘖的叶、金银木的果实、鸢尾的叶以及复羽叶栾树的花等器官表现出的活性最高。【结论】结果表明上述植物器官具有高化感活性。