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Processing tomato is an important crop in California, where ≈ 100,000 ha is grown annually. In the past, processing tomatoes have been irrigated mostly by sprinkler and furrow irrigation, although several tests have been conducted with drip irrigation, and a few growers are using subsurface drip irrigation. Yields of tomato have been shown to be sensitive to water management when the amount of irrigation water closely matches plant water use. Tomatoes have been identified as susceptible to drought stress and waterlogging at both ends of the furrow irrigation cycle. Subsurface drip irrigation is a relatively new method in which drip irrigation laterals are buried permanently 20 to 60 cm below the soil surface. This method has provided the control and uniformity of water and fertilizer distribution necessary to maximize the yield of processing tomatoes. A computerized control system maintains nearly constant soil water and nutrient concentration in the root zone by irrigating and fertilizing frequently, thus avoiding small water and nutrient stresses, especially during the critical period between first and peak bloom. During the maturation and ripening stage, irrigation and nutrient concentrations can be adjusted to increase soluble solids and to adjust the maturation rate to coincide with the harvest schedule. Maximum yield levels can be obtained when nearly all the fertilizers (N, P, and K) are injected precisely in time and space through the drip irrigation system to meet the crop nutrient requirement. Water-use efficiency (WUE), defined as the ratio of yield: unit of water used by the plant, can be maximized by using this precise irrigation and fertilization technique. Yields >200 t·ha-1 of red tomatoes were achieved in large field plot research, and commercial yields of 150 t·ha-1 were achieved in large-scale field applications with a lesser degree of control. Therefore, we predict that with further fine-tuning, commercial yields of 200 tons of processing tomatoes/ha could be achieved using a subsurface drip irrigation system with accurate water and fertility management.
Abstract
Evaluations of cooked fresh beans showed that the persistent-green color (PC) cv., Custer, was darker, greener, and less yellow than the normal-green cv., Canyon. Persistent-green color lines Xlda 71-2081 and Xlda 267-4 were intermediate between the 2. Chlorophyll concentrations were higher in all PC lines than in the normal-green cultivar but the ratio of chlorophyll a/b was lower. Chlorophyll content was significantly correlated with Gardner color values and with visual color scores. No color values correlated with pheophytin or carotene content.
Xlda 71-2081 had the highest work-to-shear values, % seed, % fiber, and highest panel scores for fibrousness. Whether the higher values were attributable to genetic controls or to a difference in maturity was not determined in this study. Little sloughing was observed. All cultivars had a slightly to moderately full, natural flavor. The PC beans were equal or superior to the normal-green cultivar in all measured quality characteristics with ‘Custer’ showing the most promise.
Pigeonpea, a subtropical legume, was successfully grown in a high-latitude (≈45°N) environment. Four short-season pigeonpea accessions from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) were subjected to three cycles of pedigree selection. Performance trials (175,000 plants/ha) were conducted on loamy sand with dryland and irrigated sites in 1991 and 1992. Thirty-eight S3-derived lines from ICRISAT ICPL 83004 were used in both years and seven S3-derived lines from ICRISAT P 2125 and ICRISAT ICPL 85010 were added the second year. Differences (P ≤ 0.05) in seed yield (kg·ha–1) were observed among the S3 lines, with a maximum yield of 1468 kg·ha–1. The lines also differed (P ≤ 0.05) for harvest index (HI), calculated as the ratio of seed yield to shoot total dry matter (TDM) with a maximum of 0.48 (line MF-26). Dryland seed yield was strongly correlated with TDM (r 2 = 0.98), HI (r 2 = 0.92), and early bloom (r 2 = 0.76). In a time-of-planting comparison of seven lines in 1992, seed yield was highest (754 kg·ha–1) at the earliest (29 Apr.) planting date and declined progressively to 178 kg·ha–1 at the latest (2 June) planting date, while HI decreased from 0.42 to 0.12. Plants were shorter at maturity in the earliest planting date.
Red-fleshed watermelons contain lycopene, a compound that has health functional properties. Watermelon intake may be restricted for individuals who have diabetes or those who limit carbohydrate intake. Recently, a low-sugar watermelon (<6% soluble solids content) was developed using traditional plant breeding techniques. Low-sugar and a commercial variety of watermelon (9% SSC) were washed, cut in half and red flesh was removed and cut into cubes. Low and high levels of artificial sweetener were added to the low-sugar watermelon. Students at a Native American school (grades 1 through 12) and adults at a Native American Feeding Center were asked to rate how much they liked or disliked the watermelon using a seven-point hedonic scale. Lycopene and other carotenoids were analyzed from samples using established methods. Artificially sweetened melons were rated as acceptable as commercial control melons for taste. Lycopene and total carotenoid levels were similar among the treatments. These results show that artificially sweetened low-sugar watermelons were acceptable to Native American consumer groups.
Mustard (Brassica spp.) cover crop residue has been reported to have significant `biofumigant' action when incorporated into soil, potentially providing disease suppression and yield improvement for the succeeding crop. The effects of growing over-winter mustard cover crops preceding processing tomato (Lycopersicon escultentum Mill.) production were investigated in six field trials in the Sacramento Valley of California from 2002–04. A selection of mustard cover crops were compared to a legume cover crop mix, a fallow-bed treatment (the current grower practice in the region), and in two of the six trials, fumigation treatments using metam sodium. Mustard cover crops removed 115 to 350 kg·ha–1 N from the soil profile, reducing NO3-N leaching potential. Soil populations of Verticillium dahliae Kleb. and Fusarium spp. were unaffected by the cover crops, and there was no evidence of soilborne disease suppression on subsequent tomato crops. Mustard cover crops increased tomato yield in one field, and reduced yield in two fields. In one of two fields, metam sodium fumigation significantly increased tomato yield. We conclude that, while environmental benefits may be achieved, mustard cover cropping offers no immediate agronomic benefit for processing tomato production.
Mustard cover crop residue has been reported to have a “biofumigant” action when incorporated into the soil, potentially providing significant disease suppression and yield improvement for the succeeding crop. Such activity could be particularly useful in processing tomato rotations, where consecutive cropping invariably results in yield decline. Agronomic and environmental effects of growing over-winter mustard cover crops preceding tomato production were investigated in three field trials between 2002 and 2004. Two mustard cover crops [`Pacific Gold', a brown mustard (Brassica juncea), and `Caliente', a blend of brown and white mustard (Sinapis alba)] were compared to a legume cover crop mix, a fallow bed treatment (the standard grower practice in this region), and, in two of the three trials, a fumigation treatment using metam sodium. No suppression of soil populations of Verticillium dahliae or Fusarium spp. was observed with the mustard cover crops, nor was there any visual evidence of disease suppression on subsequent tomato crops. In these fields, the mustard either had no effect, or reduced tomato yield, when compared to the fallow treatment. At one of two sites, metam sodium fumigation significantly increased tomato yield. The presence of a cover crop, whether mustard or legume, reduced winter runoff by an average of 50% over two years of trials. No benefit of mustard cover cropping beyond this reduction in winter runoff was observed.
Abstract
Resistance in Pisum sativum to Aphanomyces euteiches was evaluated in the laboratory by the number of oospores formed in excised root tips inoculated with zoospores of the pathogen. Significantly lower mean numbers of oospores formed in root tips of 3 moderately resistant breeding lines than in those of 3 susceptible cultivars. Results were reproduceable if test procedures were adequately controlled. A sample size of 40 root tips gave 95% confidence in detecting a 40 oospore/root tip difference between means of resistant and susceptible genotypes.
Lower mean numbers of oospores formed in excised root tips of genotypes which were resistant in greenhouse tests. Inoculum concentrations of 10 to 100 zoospores/plant caused severe disease in susceptible cv. New Era, while greater amounts of inoculum were needed to cause comparable disease in 2 resistant breeding lines.
Abstract
A table is presented from which the percentage distribution of a crop into various maturity classes can be estimated for an optimizing or non-optimizing harvest day. Two or three characteristics of the crop must be known or guessed for predictive or speculative purposes. The use of the table throws light on the type of information which must be at hand in order to work intelligently toward a once-over harvest in those perishable crops which at present are not well adapted for it.
`Jewel' sweetpotato was no-till planted into crimson clover, wheat, or winter fallow. Then N was applied at 0, 60, or 120 kg·ha–1 in three equal applications to a sandy loam soil. Each fall the cover crop and production crop residue were plowed into the soil, beds were formed, and cover crops were planted. Plant growth of sweetpotato and cover crops increased with N rate. For the first 2 years crimson clover did not provide enough N (90 kg·ha–1) to compensate for the need for inorganic N. By year 3, crimson clover did provide sufficient N to produce yields sufficient to compensate for crop production and organic matter decomposition. Soil samples were taken to a depth of 1 m at the time of planting of the cover crop and production crop. Cover crops retained the N and reduced N movement into the subsoil.
A 5-year study using winter cover crops (wheat or rye, crimson clover, and fallow) in a tomato and bean rotation indicated several soil responses to the cover crops. Advantages of crimson clover winter cover crop to the soil in a tomato-bean rotation included adding organic matter to the soil, which resulted in an increase in the amount of inorganic nitrogen in the upper levels of the soil profile and an increase in the soil's water-holding capacity. An additional benefit of winter cover crops to the soil was the potential of reduced nitrogen leaching.