Seed priming is a controlled hydration process, followed by dehydration, that allows pregerminative metabolic activity to proceed without germination. The objective of this research was to investigate the effects of priming on intrinsic characteristics of seed germination including temperature, water, and development, in order to understand how priming affects the germination of broccoli (<i>Brassica oleracea var. italica</i> Plenck) seeds. Priming of broccoli seeds consistently improved germination and emergence rate in the laboratory and field and was related to the accumulation of a specific level of hydropriming units expressed in MPa*h. Priming reduced the sensitivity of seed germination to temperature and increased the temperature range of germination but did not lower the minimum temperature for germination. Primed seeds leaked less electrolytes at supraoptimal temperatures (≥ 35°C) compared to nonprimed seeds. In the field, primed seeds produced a greater plant stand and yield under stressful emergence conditions. Under optimal conditions in the field for stand establishment, the advancement in emergence of primed seeds did not carry over to earlier, greater yields. Matric priming, using calcium silicate as the carrier in the ratio 1.0:0.8:1.8 (seed:carrier:water; by weight) for 7 d at 20°C, was superior to osmotic priming using polyethylene glycol (pEG 8000) at -1.2 :MPa in nearly all variables examined. This may be attributed to reduced respiration during priming of seeds in PEG or nutrient uptake by seeds in calcium silicate. The testa was observed to be a barrier to broccoli seed germination. Priming-induced changes to the physical characteristics of broccoli seeds included increased volume (32%) and an irreversibly expanded, and weakened testa with some minute cracking near the area where the radicle emerges. Primed seeds germinated faster, in part by maintaining a lower hydrotime constant, and thus exhibited a greater progression towards germination per unit water potential at a constant temperature compared with nonprimed seeds. It was hypothesized that, since the testa threshold was reduced after priming by expansion and formation of free spaces, the reversibly expanded embryo of primed seeds does not become immediately appressed to the testa upon rehydration. Thus the yield threshold component controlling the rate of germination of primed seeds is lower by the amount of the testa threshold. The priming effect is more than just reducing the yield threshold as indicated by a significant invigoration of seeds with split testae. Despite the increased volume as a result of the formation of free spaces, primed broccoli seeds did not imbibe more water or have a greater turgor at full hydration. Priming did not lower the minimum water potential allowing germination, and primed seeds did not plateau in water uptake but, instead, moved immediately from imbibition to expansive growth. Priming improved the germination rate of broccoli seeds at all stages of maturity with the most significant effects at stages before attainment of maximum dry weight. Dry storage of broccoli seeds at harvest able maturity (≥ 56 days after pollination) did not improve germination, indicating a lack of post harvest dormancy. / Ph. D.

The effects of dietary broccoli on the body's ability to detoxify were studied in 18 male subjects between the ages of 22-40 years. The biological parameters used for measuring detoxification were the four major urinary conjugates, namely, mercapturates, sulfoconjugates, glucuronides, and amino acid conjugates. Dietary broccoli increased the urinary excretion of mercapturates and sulfoconjugates, but did not influence the excretion of glucuronides and amino acid conjugates. A significant linear trend was observed over the six-day broccoli diet treatment for both urinary mercapturate (P<0.005) and sulfoconjugate (P<0.0001) excretion. The linear trend for the mercapturate excretion was in a dose-dependent manner, resulting in a 1.3 and 2.1 fold increase by the third and sixth days, respectively, of the broccoli diet, compared to the control. For sulfoconjugates, an unexpected decrease was observed on the first day of the broccoli diet. However, within the six-day broccoli dietary treatment, a continuous increase in conjugate excretion was observed, resulting in a 2.5 fold increase by the sixth day compared to the first day. The excretion of sulfoconjugates was not necessarily dose-dependent, and increased excretion at the highest level of broccoli (500 g) could be due to a time effect. Overall, sulfoconjugate excretion was the highest (3.98-8.91 mmole/24 h) followed by the amino acid conjugates (3.06-5.99 mmole/24 h) and glucuronides (2.85-3.54 mmole/24 h). Mercapturate excretion was the lowest (0.16-0.34 mmole/24 h). In spite of its low excretion level, the level of urinary mercapturates appeared to be the most responsive urinary conjugate to the different levels of broccoli diet. / Ph. D.

Broccoli (<i>Brassica oleracea</i> L. var. italica) has become an increasingly popular vegetable with American consumers. Much of the attractiveness of fresh broccoli is derived from this vegetable's high nutrition and excellent organoleptic properties. In a consumer response survey, Virginia Master Gardeners indicated a preference for broccoli that has less stalk and more florets by weight. The objectives of this research were to produce single unit broccoli, and to examine vacuum and shrink-film wrapping of single unit and bunching broccoli as alternatives to the standard post harvest practice of top icing in order to preserve post harvest quality attributes: vitamin C, color, odor, and turgidity. Broccoli cv. 'Symphony' was direct seeded and transplanted at two sites in Virginia (within row spacing 20 cm , .9 m centered, 3 row bed). Single unit broccoli was classified as broccoli with head diameters greater than or equal to 20 cm (i.e., equivalent to one bunch of broccoli). Single unit and bunching broccoli for post harvest experimentation was vacuum or shrink-film wrapped with plastic film wraps of varying gauges. The broccoli was held in cold storage from 12 to 22 days with no supplemental ice. Single unit broccoli was produced successfully at one site only. The yields, however, were a fraction of total bunching broccoli yields. There was no significant difference in marketable yields with either planting method (direct seeded vs transplanting) at site 2. Transplants, however, out yielded the direct seeded broccoli at site 1. Vacuum and shrink-film wrapping proved to be very effective in preserving organoleptic attributes of single unit and bunching broccoli even when never receiving ice. Vitamin C and chlorophyll retention were not influenced by wrapping. / Master of Science

The objectives of this research were i) to observe the movement of the wetting front in subsurface drip irrigated lettuce and broccoli, 2) to analyze variability in soil water tension (SWT) within the profile, and 3) to determine root distributions of subsurface drip irrigated lettuce and broccoli. Lettuce and broccoli plots at the Maricopa Agricultural Center during the 1992-93 and 1993-94 winter growing seasons were intensively instrumented with automated tensiometers. During both seasons, there was good agreement between mean daily SWT, and SWT measured before irrigation. During 1992-93, the maximum variation in mean SWT among tensiometers was 2.5 kPa. Among tensiometers within the zone of greatest root density, the maximum variation was only 1.5 kPa. Therefore, the range of SWT within the lettuce root zone was small, and tensiometer placement anywhere within the root zone would have been adequate. During 1993-94, the maximum variation in mean SWT among tensiometers was 7 kPa. The maximum variation among tensiometers within the zone of greatest root density was 5.3 kPa. The larger variation in mean SWT among tensiometers, compared to lettuce, is due to the greater water use of broccoli. Tensiometer placement will be more critical for higher water use crops. During both seasons roots proliferated around the drip tubing. These results substantiate the assumption that tensiometer placement anywhere within the zone of greatest root density will be adequate for irrigation scheduling of subsurface drip irrigated crops.

The objective of this research was to estimate a season -long water balance under one subsurface trickle- irrigated plot each of lettuce (Lactuca sativa L. var. Waldmann's Green) and broccoli (Brassica olearacea L. var. Claudia). One lettuce plot during 1992-93 and one broccoli plot during 1993-94 were intensively instrumented with automated tensiometers. Tensiometer readings and estimates of evapotranspiration were used to estimate seasonal water contents in the crop root zone, and water losses due to leaching. For the monitored portion of the 1992-3 growing season, 19.1 an of irrigation water was applied, 12.5 cm of rainfall fell, and ET, was 11.5 cm. Estimated deep percolation was 60% of total water applied (irrigation plus rainfall). Leaching was periodic, and was mostly associated with rainfall events. During the monitored portion of the 19934 season, 21.2 cm of irrigation water were applied, 8.0 an of rainfall fell, and ET, was 21.9 cm. Estimated deep percolation was 28% of total water applied. Almost all of this leaching was associated with one major rainfall event. Water stored in the root zone (top 50 cm) was relatively constant at 12-14 cm water/50 cm soil except after rainfall.

Experiments were conducted with 'BigSur' broccoli (<i>Brassica oleracea</i> var. <i>italica</i> Plenck) at two sites in fall of 1993 and at two sites in the spring of 1994 on a Hayter loam in southwestern Virginia. Objectives were to determine the tillage main-plot (CT = conventional tillage, and NT = no-tillage) and weed-control subplot (C = no overseeding or preemergent herbicide; HB = oxyfluorfen; RC = red clover (<i>Trifolium pratense</i> L.); WC = Dutch white clover (<i>Trifolium repens</i> L.); and HV = hairy vetch (<i>Vicia villosa</i> Roth) effects on broccoli yield and weed suppression. At all sites, marketable broccoli yield was equal or higher in NT than CT and was unaffected by overseeded legume living mulches. Overseeded legumes suppressed weeds as well as the HB in three of the four sites. These data show that the NT systems used in these experiments can suppress weeds and produce high broccoli yields and that overseeded legume living mulches can be effectively established after transplanting to suppress weeds without reducing broccoli yield. / Master of Science

Experiments were conducted at two sites in Blacksburg, Virginia to study the effects of tillage (conventional plow-disk and no-tillage) and overseeding (underseeding) of legume cover crops (red clover, Trifolium pratense L.; white clover, Trifolium repens L.; and hairy vetch, Vicia villosa Roth.) at transplanting on weed suppression and yield of ’Big Sur’ broccoli (Brassica oleracea var. italica Plenck). In both sites, weed suppression from overseeded red clover, white clover, and hairy vetch equalled or surpassed that of the preemergent herbicide (oxyfluorfen) control. The legumes did not affect broccoli yield components in site 1 nor head number in site 2. However, hairy vetch reduced broccoli yield and head size in site 2. These reductions were attributed to competition with the broccoli. Overseeding tended to delay broccoli yield and head number in the two sites, but this trend was not significant. Tillage system did not affect weed suppression or broccoli yield components, and there were no tillage x overseeding effects. Based on this data, overseeded legumes can provide residual weed control in no-till broccoli, thus allowing a more sustainable production method. / Master of Science

Vita. / Digitized by Kansas Correctional Industries

Nitrogen (N) status of vegetable crops is often monitored by analysis of dried plant tissues. However, dry tissue analysis often causes a significant delay between sampling and analysis. This study was conducted to examine the accuracy of a portable nitrate meter for determining petiole sap nitrate (NO₃) concentrations in broccoli (Brassica oleracea L. Italica group cv. Claudia) and cauliflower ( Brassica oleracea L. Botrytis group, cv. 'Candid Charm'). The relationship between NO₃-N concentration in fresh petiole sap and in dried petiole tissue was Studied for these crops in southern Arizona during the 1993-94 and 1994-95 winter growing seasons. Experiments were factorial combinations of 3 irrigation rates and 4 N rates, both ranging from deficient to excessive. Petioles were sampled throughout each season, and were split for sap and dry tissue analysis. A linear correlation was obtained between the two measurements in both seasons, with no consistent effect due to irrigation treatment or crop maturity. The regression coefficients did not differ among seasons. Regression equations were derived to convert petiole sap nitrate concentrations to dry tissue nitrate concentrations. These equations can be used to relate sap test measurements to existing guidelines for NO₃-N concentrations in broccoli and caulker petioles. These results suggest that the quick sap test, using the portable nitrate ion meter, is a valuable technique for monitoring N status of broccoli and cauliflower.

Field experiments were conducted during the 1995-96 winter growing season at The University of Arizona's Maricopa Agricultural Center to determine the response of broccoli and cauliflower to a factorial arrangement of water rates and nitrogen (N) fertilizer rates. Both the broccoli and cauliflower experiments were randomized complete block factorial designs with three water levels (deficient, optimum, and excessive), four N fertilizer levels (deficient, suboptimal, supra optimal, excessive), and four replications. Drip tubing was buried at a depth of eight inches along the midline of each planting bed. Irrigation was applied daily as needed to maintain the predetermined target soil water tension levels and N fertilizer (urea ammonium nitrate solution) was applied in 4 or 5 split applications. Broccoli spears and cauliflower curds were harvested weighed and graded according to prevailing commercial practices. The optimum marketable yield of broccoli of 4.6 tons/acre was achieved with a total application of 18.9 inches of water and 267 lbs. N/acre. The optimum marketable yield of cauliflower of 9.5 tons /acre was achieved with a total application of 18.5 inches of water and 178 lbs. N/acre. For both crops a nitrogen deficiency had a greater negative impact on marketable yield than either deficient or excessive water application. Optimum marketable yields, earliness and head quality for both crops were achieved when the average soil water tension level for the entire season was maintained at about 10 cbars (or 13 cbars uncorrected gauge reading).