Field resistance of perennial glandular-haired Medicago strains and alfalfa cultivars to the alfalfa weevil

Summary Field plots planted in 1986 to four, perennial, glandular-haired Medicago strains and four alfalfa cultivars were evaluated for alfalfa weevil, [Hypera postica (Gyllenhal)], abundance and feeding damage as well as plant height from 23 April through 21 may 1987 and from 25 April through 26 May 1988. The plots were located near Mead, Nebraska and both sweep and stem sampling methods were utilized. In 1987, M. glandulosa had the fewest larvae present in sweep samples on 1, 9, and 15 May, although on the last date it did not differ significantly from three other entries. The glandular-haired M. glandulosa also was among those entries having the fewest number of larvae present in stem samples on 9 May, 1987. Significant differences in the number of damaged stem tips were observed on 9 and 21 May, 1987, when M. glandulosa was among those entries having the least amount of damage. The other three glandular-haired strains had larval infestations and damage similar to those for the cultivars. Weevil abundance and damage were generally low in 1988. Medicago glandulosa was shortest of the glandular-haired strains, which were shorter than the cultivars.     

The effects of kinetin on callus characters in alfalfa (Medicago sativa L.)

Summary Three callus initiation media, B2-k, B2, and 7951, were used to study the effects of kinetin on callus initiation, morphology, histology, and regenerability in alfalfa (Medicago sativa L.). The presence of kinetin in callus initiation media retarded callus initiation, but enhanced division and differentiation of callus cells. Calluses induced on kinetin-containing media (B2 and 7951) had many compact cell aggregations, which were considered meristematic regions that might differentiate to plantlets on a regeneration medium. Visually, these calluses were compact and had many nodular structures. In contrast, most calluses induced on a kinetin-free medium were composed of large, individual cells and had friable structures without nodules. After transfer to a hormone-free medium, calluses induced on kinetin-containing media regenerated more frequently than those induced on a kinetin-free medium, but cytokinin (kinetin) autotrophism also occurred. Autotrophism was sexually transmissable and especially affected by the female parent.     

Integrated Pest management in Forage Alfalfa

Alfalfa, Medicago sativa L., is among the most prized of forages, and is grown worldwide as a feed for all classes of livestock. It is one of man's oldest crops, and its cultivation probably predates recorded history. In addition to its versatility as a feed, alfalfa is well known for its ability to improve soil structure and, as a legume, is an effective source of biological nitrogen. As a perennial crop, alfalfa has a lifespan approaching 5 years, but in some areas of the world fields may remain productive for considerably longer. Such a long stand life affords ample time for the establishment and development of a diverse community structure by an abundance of organisms. In spite of system perturbations caused by frequent harvests and occasional pesticide applications, an alfalfa field provides a temporal stability which is uncommon among field crops. As a result of this stability, alfalfa supports an immense diversity of flora and fauna which, at times, exceeds that of riparian ecosystems. While most of alfalfa's inhabitants have little or no impact on it as a crop, a few are capable of causing extensive damage. Arthropods, plant pathogens, weeds, vertebrates, and plant parasitic nematodes can all cause significant yield and/or quality reductions and frequently contribute to shortening the productive life of the stand. This paper reviews the major strategies which have been developed to manage many of these alfalfa pests including: host plant resistance; cultural controls, such as harvest strategies, irrigation management, sanitation, planting schedules, and crop rotation; mechanical and physical controls; chemical control; and biological controls. Multiple pest interactions, e.g. insect-insect; insect-disease; insect-weed, and their management are discussed. Potential conflicts arising from the use of strategies which may reduce one pest but exacerbate others are also examined. A cross index of management strategies and their role in managing multiple pests is provided. Computer models, both ecological and economic, and their role in alfalfa pest management are discussed. Selected information sources on alfalfa and alfalfa IPM available over the Internet are listed. Alfalfa's role in the agricultural landscape, as it relates to pests, natural enemies, and pest management in other cropping systems as well as its role in crop rotation, is considered.     

高产奶牛高效全混合饲料配方筛选试验

中国荷斯坦奶牛60头饲喂4种不同紫花苜蓿干草配比、不同精粗比的日粮,以研究日粮配方对奶牛产奶量、乳脂率、经济收益的影响.试验结果说明,大比例紫花苜蓿干草日粮（紫花苜蓿为24%DM）乳脂率显著（P＜0.05）或极显著提高（P＜0.01）;日粮营养水平提高,产奶量提高（P＜0.05 P＜0.01）;最佳经济效益日粮为含大比例紫花苜蓿,营养水平较低的日粮（P＜0.01）;在大的精粗比例下,紫花苜蓿干草不是日粮成本的限制因素,而青贮饲料配比为日粮成本的限制因素.合理安排精粗比例,适当使用紫花苜蓿干草,可提高奶牛饲养经济效益.     

磷、锌、硼、钴对苜蓿肥效与施用技术研究

经二年在庆阳黄土高原试验进行磷、锌、硼、钴作苜蓿基肥和苜蓿种子丸衣化田间试验。结果证明锌、硼用于苜蓿种子丸衣对苜蓿有显著增产效果,但锌与硼配合会互抑制降低肥效,其它处理对苜蓿投有显著增产效果。     

杀菌剂拌种对紫花苜蓿,苏丹草不同活力种批出苗的影响

在４０％土壤饱和持水量和最适萌发温度下,研究了甲基托布津、甲霜灵、杀毒矾和福美双等杀菌剂拌种对紫花苜蓿和苏丹草出苗的影响;进而探讨了不同活力的供试种种批对杀毒矾拌种的反应。４种参试杀菌剂以杀毒矾效果最好,与对照比,其可使紫花苜蓿和苏丹草的存苗率分别提高１４１．９％和３７．７％（Ｐ＜０．０５）,使紫花苜蓿死苗率降低８０．８％（Ｐ＜０．０５）。其他３种杀菌剂亦可显著（Ｐ＜０．０５）提高紫花苜蓿种子的存苗率和降低死苗率,提高存苗率的效果依次为甲霜灵（１０９．７％）、甲基托布津（８３．９％）和福美双（４８．４％）,但对苏丹草种子作用不显著。杀毒矾处理对中活力和高活力紫花苜蓿种子较低活力种子更为明显、有效,与对照比,中活力和高活力种批的存苗率分别提高了１１１．５％和１００．０％,而低活力种批仅提高了３１．０％。但杀毒矾对苏丹草不同活力种批的作用效果不显著。     

新疆阿勒泰新垦区苜蓿病害调查与分析

对新疆阿勒泰地区三县一市新垦殖的２８１７项目区苜蓿病害进行了调查研究,共发现１１种病害,其中田野菟丝子、丛枝病、炭疽病等发生普遍,且为害严重,我区常见和主要的苜蓿病害大多均已在新垦殖区发生,且程度已与老的苜蓿生产区相差无几。据此提出了对我区苜蓿病害防治的几点意见和建议     

The potential of selection and breeding for improved salt tolerance in lucerne (Medicago sativa L.)

Summary Four cultivars of Medicago sativa L. were subjected to selection for improved salt tolerance using a salinized solution culture technique at 250 mM NaCl. Selections were made after two weeks growth, based upon seedling shoot length differences. High (shoot lengths 14–31 mm) and low (7–12 mm) selection lines were established. Unselected shoot lengths ranged from 0–11 mm. Selection intensities ranged from 0.17% to 0.22% for the high selection lines, and from 0.30% to 1.05% for the low selection lines.Eleven selected plants from cv. CUF 101, and 10 from Local Syria were grown on and polycrossed. A sample of progeny seed from each was grown at 8 NaCl concentrations in solution cultures. Selected line seedlings produced shoots at 225, 250, 260, and 275 mM NaCl, whereas unselected material failed to grow above 225 mM NaCl. A second cycle of selection at 280 mM NaCl with these two cultivars achieved selection intensities of 0.21% and 0.45% for high and low selection lines, respectively. Selected lines grew and produced shoots at 300 mM NaCl.Seedlings derived from 1st and 2nd selection cycles and unselected control material were grown for 6 weeks at 0, 150, 175, and 200 mM NaCl in a sand culture experiment. The high selection line produced significantly greater shoot fresh weight, dry weight, and % live shoot weight than the unselected control material. Clearly selection as practised here can isolate individual seedlings having enhanced genetically based tolerance to NaCl, which is manifest in mature plants derived from polycrossing those selected individuals.