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Open access

J. F. Pereira, H. J. Hopen, and W. E. Splittstoesser

Abstract

2,4 Dichlorophenyl-p nitrophenyl ether (nitrofen) was more injurious to field transplanted cabbage at the 3 leaf than at the 6 or 9 leaf stages; ‘Hybelle’ was more tolerant than ‘Rio Verde’. 2,4 Dinitro-p-trifluoromethyl phenyl ether (fluorodifen) caused greater injury than nitrofen when applied as a preemergence treatment on direct-seeded cabbage or as a postemergence treatment on transplanted cabbage.

Open access

Walter E. Splittstoesser and Franklin W. Martin

Abstract

The troptophan content was determined in 29 cultivars of tropical root and tuber crops: (Manihot esculenta Crantz, Dioscorea alata L., D. rotundata Poir., D. esculenta Burkill, D. bulbifera L., D. trifida L., Ipomea batatas L., Xanthosoma sagittifolium L. Schott, Colocasia esculenta L. Schott, Canna edulis Ker., Maranta arundinacea L., and Calathea allouia Lindl.) They contained 0.1 to 1.1 g tryptophan per 100 g protein and were below the FAO reference protein. Sufficient diversity existed between cultivars for troptophan per g of dried tissue to recommend further trials with D. alata cv. Florido, D. esculenta cv. Spindle, X. sagittifolium cv. Aguadillana and Colocasia esculenta cv. Martin. These contained 50% to 79% as much tryptophan as the FAO reference protein and have excellent cooking qualities.

Open access

Shim Kyung-Ku, J. S. Titus, and W. E. Splittstoesser

Abstract

Senescing apple leaves absorbed 80% of applied urea in 48 hr with greater absorption in light than in darkness. The amount of urea absorbed paralleled the increase in the concn of soluble N and urea N. The bulk of the increase in soluble N was urea and the changes in total soluble N paralleled the changes in urea N. During leaf senescence, chlorophyll, total N and protein declined and much of this N was translocated into storage tissues. Trees which received a post-harvest urea spray produced a significantly greater amount of shoot growth and fruit set of apples than trees receiving no urea or a soil application of urea. The yield was not significantly different between trees receiving a 5% urea spray and trees receiving the soil application of urea. However, the efficiency of N utilization by a 5% urea spray was 4-fold greater than the soil application.

Open access

Kyung-Ku Shim, J. S. Titus, and W. E. Splittstoesser

Abstract

Urea was applied to the foliage of 1-year-old apple Malus pumila Rehd., cv. Mailing Merton 106 (MM 106) trees during senescence and the fate of the urea C and N determined. The urea C was readily released as CO2, but abscised leaves still contained 18% of the total. Only 5% of the urea C was found in storage tissues (shoot bark and wood, stem bark and wood, and roots). By the time the leaves abscised, this C was found primarily in protein, sugars, and amino acids of storage tissues. Small amounts of urea were still present. The urea N was translocated from the leaves as amino acids or urea. At leaf abscission, 30% of the initial N was still present in the leaves. During senescence, storage tissues from untreated trees increased 1.5-fold in N while similar tissues from urea-treated trees increased 3-fold. This additional N was found primarily in stem and shoot bark and in the roots. Small amounts of N were stored as amino acids but the bulk of the urea N was stored as protein.

Open access

K. K. Shim, J. S. Titus, and W. E. Splittstoesser

Abstract

Urea-14C was supplied to the roots of stem-ringed 1-year-old apple trees on which bark segments were isolated above and below the ring. Unmetabolized urea was translocated to shoots and leaves although considerable metabolism occurred especially in bark tissues. Most of the 14C in wood tissue was associated with urea. In bark tissues, 20% to 30% of the 14C was in amino acids and sugars by 120 minutes. The accumulation of urea-14C and products of its metabolism in isolated bark segments indicated that the occurrence of these materials in this tissue was via radial translocation from xylem tissue, and that the main upward translocation pathway of urea supplied to roots is through the xylem.

Free access

W. Msikita, R.M. Skirvin, J.A. Juvik, W.E. Splittstoesser, and N. Ali

Seeds of `Burpless Hybrid' cucumber (Cucumis sativus L.) were separated from their seedcoats and excised into pieces comprising an embryonic axis and two cotyledons. The seed pieces were disinfested and explanted on modified Murashige and Skoog medium with 16 combinations of BAP (2.0, 3.0, 4.0, 5.0 mg·liter-1) and NAA (0.0,0.1,0.2,0.3 mg·liter-1). On all media, embryonic axes germinated and grew into whole plants within 4 weeks, but did not flower. Cotyledons developed adventitious shoots and male flowers on most media. A few female flowers developed. The best shoot regeneration and the most female flowers were observed on medium with 2.0 mg BAP and 0.3 mg NAA/liter. One of the female flowers was pollinated in vitro and it developed a small fruit with viable seed.

Free access

Y. Mohamed-Yasseen, T. L. Davenport, W. E. Splittstoesser, and R. M. Skirvin

A method for regeneration of somatic embryogenesis from witloof chicory is described. Explants were taken from leaf veins of stored witloof chicory. Internal bacterial infection was found in 100% of the leaf bases but decreased gradually toward the leaf tips. Bacterial free explants were taken from the distal third and cultured on Murashige and Skoog medium (MS) containing 1.3 uM 2,4-D, 1.3 uM kinetin, and 100 mg/L casein hydrolysate. A pale yellowish, nodular callus formed after 4 weeks and were maintained in the same medium for 8-12 months with one change to a fresh medium every 4 weeks. Callus were suspended in the same medium without agar for 4-6 weeks with one change to a fresh medium every 2 weeks. Embryo-like structure appeared upon transfer to MS liquid medium containing 1.8 uM benzyladenine. Embryo germination was accomplished in 1/4 strength of MS medium with 01 without 1 g/L activated charcoal.

Free access

Y. Mohamed-Yasseen, T. L. Davenport, W. E. Splittstoesser, and R. M. Skirvin

Bulb formation in vitro is considered to be advantageous over shoot formation. Bulbs were farmed in vitro from onion inflorescence explants cultured in bulb induction medium composed of Murashige and Skoog (MS) medium supplemented with 120 g/l sucrose and 5 g/l activated charcoal under long day photoperiod. Bulbs were also induced in the same medium from shoots which were first regenerated from onion inflorescences in MS alone or MS containing either 4.4 uM benzyladenine or 0.005, 0.01, 0.05, 01 0.1 uM of thidiazurone. This system of in vitro bulb formation obviates shoot elongation, rooting, and acclimatization steps normally required when shoots are regenerated.

Open access

Walter E. Splittstoesser, Franklin W. Martin, and Ashby M. Rhodes

Abstract

Principal component analysis based on 19 characters (amino acids and protein measurements) was used to analyze differences among 46 cultivars in 5 yam species: (Dioscorea alata L., D. rotundata Poir., D. esculenta Burkill, D. trifida L.f., and D. bulbifera L.). Considerable diversity existed in amino acid composition among cultivars within species and also between species. Most of the cultivars contained adequate amounts of the essential amino acids except those containing sulfur. The quantity of sulfur-containing amino acids was not associated with individual species or geographical sources. Large variation in the methionine to half-cystine ratio was found, and these amino acids in the 5 species composed 50% to 79% of the amount found in the FAO reference protein. The essential amino acids leucine, phenylalanine, and threonine were present in sufficient excess to supplement proteins from other sources. The pattern of diversity for amino acids was compatible with current biochemical knowledge and suggested that in yams most amino acids are inherited independently of each other.