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  • Author or Editor: P.L. Minotti x
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Abstract

There are, no doubt, hundreds of measurements that might reflect quality when all perspectives are considered (growers, shippers, processors, retailers, consumers). Many of the “things” measured will be affected to a greater or lesser extent by manipulating the nutrient environment and there are approximately fifteen essential elements alone to manipulate.

Open Access

Abstract

Foliar sprays of Ca(NO3)2 or CaCl2 completely controlled lettuce tipburn in the variety ‘Meikoningen’ when directed to susceptible immature leaves. Analysis of treated and untreated plants showed that treatment markedly increased the Ca content of tipburn susceptible leaves and revealed a 5-fold increase in Ca content as one progressed from immature heart leaves to mature basal leaves in untreated plants. Foliar sprays of organic acid salts, particularly oxalate, accelerated the development of tipburn and increased its severity. When Ca and oxalate treatments were alternated, application of Ca at the beginning of the dark period and oxalate in the morning resulted in markedly less tipburn than application of these sprays in the reverse order.

Open Access

Abstract

A pattern of diurnal fluctuation in the nitrate concentration of young field grown beets (Beta vulgaris L.) was established. Plants assayed every 4 hours over a 52-hour period in late May showed greater than 2-fold differences with maximum concentrations at 4 am and 8 am and minimum concentrations at 4 pm. Thus, adjustments in harvest time may help minimize nitrate levels in vegetables. Moreover, diurnal fluctuations should be taken into account when predicting the adequacy of soil nitrate levels by tissue analysis.

Open Access
Authors: and

Abstract

Two field experiments were conducted with two cultivars of transplanted tomatoes (Lycopersicon esculentum Mill.) with and without plastic mulch, varying the initial rate of N fertilizer, but maintaining the total N rate at 168 kg·ha–1 by sidedressing. In 1982, 0 and 112 kg·ha–1 initial N rates, and bare ground, black mulch, and clear plastic mulch were compared on a gravelly loam soil. In 1983, initial N rates used were 34, 67, 101, or 134 kg·ha–1, with bare ground and clear mulch on a silt loam soil. Effects of the plastic mulch dominated both experiments. Mulching increased rate of basal branch appearance and led to early flowering on branches. Total plant growth, as measured by vine weights at final harvest, was increased by mulch in both years. Mulching increased early yield only in 1983, but increased total yields by 13% and 79% in 1982 and 1983, respectively. Initial N fertilizer rates did not influence total yields significantly in either experiment, although high initial N rate, combined with clear plastic mulch, led to a significant decrease in percent marketable fruit in 1982. In 1983, mulching increased shoot concentrations of N, NO3-N, P, K, Ca, Mg, Cu, and Β (P = < 0.01) in spite of the fact that mulched plants were larger than unmulched plants at sampling time, 24 days after transplanting. Nitrogen fertilizer increased only the N and P concentrations and to a lesser extent than did the mulch.

Open Access
Authors: and

Abstract

Two experiments were conducted on a gravelly loam soil of low N status to determine the amounts and timing of N fertilizer needed for high early and total yields of fresh-market tomatoes grown with or without clear plastic mulch. In both years, the mulch slightly increased early flower number, hastened flower production, and increased early yield. Hastening of maturity of plants on mulch resulted in a 22% increase in ripe fruit in the short (118-day) season of 1984 and a decrease in percent green fruit at final harvest. A N rate of 84 kg·ha−1 increased total yields compared to 0 N, whereas 168 kg·ha−1 of N decreased early yield in 1984 but not 1985. Applying one-half of the N at planting and sidedressing the remaining half was just as effective in increasing yields as applying all the N at planting, even with mulched plants. Low tissue NO3-N concentration (< 0.2%) 3 weeks after transplanting reflected insufficient N application for optimum yield but also resulted from limited soil moisture when applied N was adequate. The mulch has increased P consistently and, to a lesser extent, the K concentration in young tomato plants, whereas the effects of mulch on mineral concentration of other elements have varied with year, soil type, and climatic factors.

Open Access
Authors: and

Abstract

Field and greenhouse experiments were conducted to encourage growth of basal branches of tomato (Lycopersicon esculentum Mill.) through apex removal and use of plastic mulch. In the greenhouse experiment, apex removal (topping) delayed anthesis of the first flowers by 6 days, but then the faster branch growth increased flower cluster numbers more rapidly on topped plants than on untopped plants. In the first field experiment, apex removal and clear plastic mulch stimulated basal branching and led to a 25% increase in yields of the first four harvests, with the combination of treatments having additive effects. Mulching increased leaf concentrations of P, K, Ca, and NO3-N and decreased Na concentrations, whereas topping increased Ca, Mg, and Na concentrations in leaves sampled 24 days after transplanting. In 1985, mulching resulted in a 54% increase in early yields, but topping depressed marketable early yields by 20% because of fasciation (“catfacing”). In 1985, early yield of an early processing line was stimulated more by mulch than were two later-flowering fresh-market cultivars.

Open Access

Tomato (Lycopersicon esculentum Mill.) plants grown on polyethylene (PE) mulch in New York State frequently have more branches and increased mineral nutrient uptake and yield than plants not mulched. In four field experiments conducted on a silt loam soil, clear PE mulch stimulated root extension shortly after transplanting. One week after transplanting, roots were significantly longer for mulched than for unmulched plants in all four experiments, whereas aboveground dry matter differences did not become significant until 14 days after transplanting in two of four trials. Mulching increased branching, hastened flowering on basal branches, and increased concentration of major nutrients in the aboveground parts. In the field, stimulation of aboveground growth due to mulch might be brought about by warming of the stem by air escaping from the planting hole in the mulch. However, an experiment with black, white, or clear mulch, in which the planting hole was either left uncovered or covered with soil, showed no effect of hole closure on branching even though air temperature near the stem was increased when holes were left uncovered. The results taken together imply that the increased aboveground growth observed with mulching is a consequence of enhanced root growth and nutrient uptake.

Free access

We report three N rate experiments conducted on a gravelly loam soil to assess the N status of potato (Solanum tuberosum L.) using a Minolta SPAD-502 chlorophyll meter. Highly significant linear and quadratic trends were obtained for the regression of N rate on marketable tuber yields and SPAD readings. SPAD readings were taken at four times during the growing season and decreased as plants aged. Based on regression analysis, the early season SPAD readings, associated with N rates giving maximum marketable tuber yields, ranged from 49 to 56 units depending on year, variety, and location. Potato variety significantly affected SPAD values in eight of the 12 situations where readings were obtained. Precision in interpretation was improved when the highest N rates were considered “reference strips” to standardize the SPAD readings across varieties and growing seasons. Our results suggest that field SPAD readings can readily identify severe N deficiency in potatoes, have the potential to identify situations where supplementary sidedressed N would not be necessary, but would be of limited value for identifying situations of marginal N deficiency unless reference strips are used.

Free access

Unmulched and polyethylene-mulched tomatoes (Lycopersicon esculentum Mill.) were grown with and without starter fertilizer (SF) in four field experiments. The fields varied as to residual P level and the amount of P incorporated before planting. No benefits from SF were obtained on a soil with high residual P that was moderately fertilized with P before transplanting or on a soil with low residual P that was heavily fertilized with P. A positive effect from SF was observed only when residual P was low and no P was broadcast, and this was true in mulched and umnulched plots. No significant SF by mulch interaction was obtained in these experiments even though mulching consistently increased shoot P concentrations and fruit yield. The mulch was beneficial even under conditions where unmulched tomato leaves contained 0.4 % P 3 weeks after transplanting, indicating that factors in addition to improved P nutrition are also involved in the mulch effect.

Free access

Abstract

Tomatoes (Lycopersicon esculentum Mill.) were sampled for laboratory analysis of nitrate nitrogen (NO3-N) in one greenhouse and four field experiments. A ratio of about 3:1 (petiole NO3-N to whole leaf NO3-N) was found over a wide range of conditions for the third leaf below the growing tip and leaves further below this point. The ratio was higher for the very youngest leaves. Nitrate-N increased with leaf age and then remained relatively constant. Whole leaves proved just as effective as petioles for reflecting changes in available N.

Open Access