Field studies were conducted in 2006 and 2007 to evaluate the tolerance of autumn-planted cabbage and turnip green to halosulfuron applied the previous spring to cantaloupe. Main plots were three levels of soil pH: maintained at a natural pH level, pH raised with Ca(OH)2, and pH lowered with Al2(SO4)3. Subplots were a factorial arrangement of two halosulfuron application methods and three halosulfuron rates. Halosulfuron application methods were PPI or POST after transplanting to the edges of mulch-covered seedbeds. Halosulfuron rates were 35 and 70 g ai/ha, along with a nontreated control. Cantaloupe were transplanted, maintained weed-free, and evaluated for yield response. After cantaloupe harvest, direct-seeded turnip green and transplanted cabbage were established in September of each year and evaluated for crop tolerance and yield. Data indicated nonsignificant main effects of soil pH and halosulfuron application method on cantaloupe yield. However, in 2007 cantaloupe yields were significantly reduced, by 16 and 20% for halosulfuron applied at 35 and 70 g/ha, respectively. For all turnip green and cabbage response parameters, interactions were nonsignificant between application method and rate, soil pH and rate, and soil pH and application method, along with the three-way interaction. After 6 mo, there was no evidence of stunting from halosulfuron carryover in 2006 to direct-seeded turnip green and in both years to transplanted cabbage. Visual estimates of stunting to direct-seeded turnip green ranged from 9 to 16% for halosulfuron at 35 and 70 g/ha, respectively, in 2007, but all stunting was transient and turnip green yield was not affected.

To develop synthetic varieties (Syn) of broccoli for organic agriculture, we initiated a breeding programme from a landrace (LR). A Syn was obtained through a farmer-assisted selection programme that mirrors the original LR. The diversity level of the Syn was assessed using 14 putatively neutral microsatellite markers (simple sequence repeats (SSR)) and seven SSR related to genes involved in flowering control. Four commercial F1 hybrids were also assessed. Despite the strict selection procedure applied by the farmer to reproduce the LR annually and to obtain the Syn, the detected diversity level was high and similar to that of non-selected LRs. The possible reasons for these genetic outcomes (i.e. SSR position in the genome and farmer selection methods) are discussed here.

Profiles of proteins synthesized in vivo in radicle tips were compared among unaged, artificially aged (controlled deterioration: 10% moisture content at 42°C for 3 weeks), osmoprimed (−1.5 MPa polyethylene glycol 6000 at 20°C for 1 week), and artificially aged and subsequently osmoprimed cauliflower (Brassica oleracea L.) seeds. Germination and initiation of incorporation of 35S-methionine into radicle tips were delayed by controlled deterioration. Osmopriming accelerated these processes and also alleviated the delays. The labelled proteins were analysed by two-dimensional gel electrophoresis and fluorography. Proteins were found whose expression correlated with the rate of germination, and was reduced by controlled deterioration but enhanced by osmopriming. Subsequent osmopriming reversed the effect of controlled deterioration and even caused an enhancement up to the level of unaged osmoprimed seeds. These proteins appeared to be related to processes preceding visible germination. In unaged seeds, formation of the proteins in the radicle tip began upon imbibition but decreased towards visible germination. On silver-stained gels, one of the proteins was shown to be mobilized by the time of radicle protrusion, while all were found in dry seeds. Proteins whose pronounced expression was observed only after both treatments were also found.

A partial amino acid sequence of a vigour-related protein, V-1, from cauliflower (Brassica oleracea L.) seeds was obtained, after isolation by two-dimensional gel electrophoresis and gas-phase micro-sequencing. The sequence was found to have high homology to soybean seed maturation proteins. However, the position of the sequence in the V-1 polypeptide suggests that the V-1 and soybean proteins have different polypeptide structures. An osmoprimed seeds cDNA library was constructed and has been screened by a cDNA probe derived from the V-1 sequence. Two cDNA clones with high homology to aspartic protease (EC 3.4.23) from barley grain were isolated. The expression of putative aspartic protease mRNA was found to be enhanced by osmopriming, however the clones were found to have no significant sequence homology to the V-1.

Many of the characteristics of common purslane that describe this species as a “weed” are also desirable traits for a living mulch. Common purslane was investigated as a living mulch in spring broccoli production in Connecticut and was compared with mechanical and chemical weed control, as well as black plastic mulch. Common purslane seed was broadcast prior to transplanting broccoli in late May 1993 and in early June 1994. Broccoli yields with the purslane living mulch were comparable to yields with conventional methods of weed management and with no reduction in crop quality. Common purslane living mulch was able to effectively compete with weeds in broccoli when between-row areas were kept relatively weed-free by hoeing or hand pulling during the first 2 weeks after broccoli transplanting. High levels of weed control and ground cover occurred when purslane became established between crop rows. Broccoli plants were tolerant of purslane living mulch and weeds up to a critical threshold level without a significant reduction in yield. Purslane living mulch established through periodic mechanical weed management was determined to be the most economical treatment in the study. While including purslane living mulch in a spring broccoli crop production system may be a novel approach to controlling weeds, the strategies involved in this system still rely on basic weed management principles.