Transfer of resistance to race 2 of Plasmodiophora brassicae from Brassica napus to cabbage (B. Oleracea spp. Capitata). IV. A resistant 18-chromosome B1 plant and its B2 progenies

Summary The somatic karyotype and meiotic chromosome behavior were studied in an 18-chromosome B₁ plant derived from backcrossing a triploid (Brassica napus x B. oleracea ssp. capitata) F₁ hybrid to cabbage. It is considered that cabbage chromosomes no. 1 and no. 7 were substituted by two shorter B. napus chromosomes. Meiotic disturbances were more apparent during the late stages of second division. Seed fertility of this plant was largely restored in the second backcrosses with both cabbage and broccoli. 18-chromosome B₂ plants resistant to race 2 of Plasmodiophora brassicae were recovered among the progenies.Contribution no. J. 725 from the Research Station, Research Branch, Agriculture Canada, St-Jean, Québec J3B 6Z8.     

Relative sensitivity of a herbicide-resistant rutabaga genotype to cyanazine and metribuzin

Growth and photochemical response of triazine-susceptible and -resistant rutabaga ‘Laurentian’ genotypes to cyanazine (chloro-s-triazine) and metribuzin (methylthio-as-triazine) were evaluated. The young seedlings of the susceptible rutabaga were killed when cyanazine or metribuzin were applied either pre- or post-emergence. The triazine-resistant rutabaga, however, displayed a differential response to these herbicides. Metribuzin applied pre-emergence killed the seedlings at 0.4 kg ha^?1, and at 0.2 kg ha^?1 the growth was severely affected. Cyanazine even at higher rates applied pre- or post-emergence failed to inhibit growth in these plants.Chlorophyll fluorescence in leaf sections at the cotyledonary, 2-leaf and 4-leaf stages in the susceptible plants increased by 130 and 172% in response to 10^?5 M cyanazine and metribuzin, respectively, suggesting that Photosystem II reactions in these plants were severely impaired. In resistant plants, there was little or no leaf chlorophyll fluorescence (LCF) increase at this herbicide concentration. However, at 10^?4 M cyanazine and metribuzin, the LCF in resistant plants increased significantly and the increase was greater in response to metribuzin (86%) than to cyanazine (51%). This indicates that with these triazine-resistant genotypes, metribuzin is relatively more potent and at high rates is capable of interfering with photosynthesis.     

A comparison of methods for hybrid seed production using self-incompatibility in swedes (Brassica napus ssp. napobrassica)

Procedures for producing seed of hybrid swedes using self-incompatibility were examined. Single-cross, double-cross and modified double-cross hybrids were compared in isolation plots using natural pollinators and in polythene tunnels using blow-flies. With good coincidence of flowering and the same flower colour, nearly 100% hybrid seed was produced by natural pollinators with the single-crosses, the double-cross and one of the two modified double-cross hybrids; the other modified double-cross hybrid produced 87%hybrid seed. With poor coincidence of flowering and different flower colours the proportion of hybrids dropped to 61%. Using different flower colours and blow-flies as pollinators in polythene tunnels, higher levels of outcrossing were produced than in isolation plots with natural pollinators; the opposite result was obtained when the same flower colour was used. This revised version was published online in July 2006 with corrections to the Cover Date.     

Boron nutrition and mobility,and its relation to the elemental composition of greenhouse grown root crops I. Rutabaga

Abstract

The nutrition and mobility of B, and its relation to the elemental composition of two cultivars of rutabaga (Brassica napus ssp. rapifera cv. Laurentian and Wilhelmsberger) plants were investigated in greenhouse experiments. Laurentian exhibited a greater response than Wilhelmsberger to continuing B deficiency as indicated by the severity in the roots of brown heart, of external roughness and elongation and of the decrease in B concentration. Signs of B deficiency were not found when the B contents of the root and young leaves were 27 and 56 ug g‐1 DM respectively. Root B levels of 14 and 17–20 μg g^‐1 gave moderate and slight internal signs of brown discoloration. Foliar applications of B partially restored the B concentrations of the roots; however, the mechanism of movement was unclear. The Mg, Mn and Zn contents of roots were the only elements that consistently increased and accumulated under B deficiency. The relative element composition of the root compared to the mature leaves is consistent with the root being supplied predominantly with nutrients by the phloem. Nutrient retranslocation was assessed from the ratio of element concentration in the roots or young leaves to that in the mature leaves. Although Mg, Mn and B exhibited limited mobility under adequate B nutrition they were translocated from mature leaves to younger tissues under B starvation. It is concluded that Wilheimsberger is by virtue of its greater capacity for the retranslocation of B to roots, less sensitive to B deficiency and the brown heart disorder.     

饲用灰萝卜的生物学特性及栽培技术

2002-2008年对引进的灰萝卜进行了生物学特性观察和丰产栽培技术研究.结果表明:灰萝卜是一种高产优质的饲料作物,具有易栽培、产量高、品质好、适应性广以及粮菜兼用和用作绿肥等特点.适宜贵州省广大农区及相似生态区种植.     

花溪灰萝卜生产试验

于2009-2012年采用3年3点试验,以威宁芫菁甘蓝（Brassica napobrassica cv.Weining）为对照,对花溪灰萝卜（B.napobrassica cv.Huaxi）在贵州山区的生产适应性和生产性能进行了研究。结果显示,花溪灰萝卜生育期为235～245 d,鲜草产量101 340 kg·hm-2,干草产量15 840 kg·hm-2,种子产量2 980.5 kg·hm-2,显著高于对照品种（P<0.05）。本研究表明,花溪灰萝卜是一种生育期短、产量高且适应性强的冬春季牧草资源。     

贵州山区芜菁甘蓝的多用途利用及产业发展建议

为了充分挖掘芜菁甘蓝的价值及用途,提高产值效益,推动芜菁甘蓝多元化利用产业发展,对芜菁甘蓝菜用、肥用、观赏、饲用、药用、油用等用途方面的研究利用情况进行介绍,发现芜菁甘蓝是制作食材的好原料、改良土壤的优良作物、观光农业新宠、优质饲料来源,还是提高免疫力的良药;在此基础上,结合实际提出完善品种管理、强化品种选育、实施良种良法配套、促进转化应用、实现价值最大化等芜菁甘蓝多用途利用的发展建议,使芜菁甘蓝的优势得以充分利用,实现多用途利用。