S. Honma

Interspecific crossability among four species of Vigna food legumes

SummaryInterspecific crossability among four species of Vigna, namely, V. radiata (mungbean),V. mungo (black gram), V. umbellata (rice bean) and V. angularis (adzuki bean), was investigated. Pod-set and percentages of pods harvested varied with the combinations of two parental cultivars of each species for most of the interspecific hybrid crosses. The use of intraspecific hybrids as parents was slightly superior to cultivars for interspecific hybridization. A remarkable increase in viable seed production was found for the interspecific cross,V. radiata x V. umbellata, by using intraspecific hybrid as parents. Furthermore, a successful interspecific hybrid of V. mungo x V. angularis was accomplished through the use of intraspecific hybrid parents. Reciprocal cross differences were common in all the interspecific combinations. Except for the cross between V. umbellata and V. angularis, all other reciprocal interspecific crosses were unsuccessful.Viable seeds were obtained from the interspecific crosses of V. radiata x V. mungo, V. radiata x V. umbellata and V. mungo x V. angularis. Hybrid plants were obtained from cultured embryos for the interspecific crosses of V. radiata x V. angularis, V. umbellata x V. angularis and V. angularis x V. umbellata. The reciprocal hybrid of the interspecific cross between V. umbellata and V. angularis was successfully made for the first reported time.Growth and lethality of the interspecific hybrid seedlings were influenced by the genotypes of both parental species. Parental genotypes also affected the fertility of interspecific hybrids. Complete hybrid sterility was found in the interspecific crosses of V. radiata x V. umbellata, V. radiata x V. angularis and V. mungo x V. angularis; while reduced fertility was observed for the interspecific hybrids of V. radiata x V. mungo, V. umbellata x V. angularis and V. angularis x V. umbellata.

Emergence response of the pepper at low soil temperature

SummaryOne-hundred and five cultivars representing s species of Capsicum were screened at constant 13, 16, 18°C and greenhouse temperatures. Daily observation on emergence were made for 60 days following seeding in flats.Using a calculated emergence index as the criterion for emergence at low temperatures, the various cultivars were classified by species. Within the C. annum group significant differences were found between cultivars for the lowest and highest index suggesting heritability of this trait. The fowest indexes for all temperatures was a cultivar from the C. baccatum v. pendulum group.

Dormancy in peppers

Abstract Studies were conducted on 19 cultivars representing 4 species of Capsicum to determine the expression of dormancy in seed germination and emergence. Differences in dormancy were found among cultivars. Fruit age was shown to affect dormancy. Warm, dry storage shortened the length of dormancy while still maintaining a high level of emergence.

Hybridization between pascal celery and parsley

SummaryPascal celery cv. Golden Spartan was hybridized with parsley which is immune to celery blight (Septoria apiicola). Three F1 hybrids were obtained from over a thousand seedlings grown from the pascal celery parent. The F1 plants were intermediate for most characters. Segregation for petiole color in the F2 generation demonstrated that a hybrid actually occurred. Segregation for late blight resistance occurred independently from petiole color.

Results of crossing Brassica pekinensis (Lour.) Rupr. with B. Oleracea L. Var. Acephala Dc.

Success in obtaining an interspecific hybrid between B. pekinensis and B. oleracea var. acephala was possible through the use of the Chinese cabbage as the seed parent and the use of the growth regulator, N-m-tolylphthalamic acid. The hybrids appeared vegetatively intermediate between the parents except for the inflorescence which appeared more like the kale parent. The F1 was backcrossed with ease to the Chinese cabbage parent using the hybrid either as the pollen or seed parent. No backcross was made to the kale parent. Segregation in the F2 was continuous for most characters studied.

Evaluation of screening techniques and determination of criteria for assessing resistance to Corynebacterium michiganense in tomato

SummaryWhen screening populations segregating for resistance to Corynebacterium michiganense a rapid and reliable inoculation technique is needed. From the several techniques tested, inoculation of the petiole was found to give better differentiation of resistant and susceptible plants than did inoculation of the root or leaf. When petiole-inoculation was compared with stem-inoculation the latter showed the lowest environmental variation and is suggested for use in genetic studies. Stem-inoculation involved clipping the stems of 4 week old seedlings 1 cm above the cotyledonary leaves with scissors which had been dipped in inoculum.Petiole inoculation and, to a lesser degree, stem inoculation failed to produce uniform infection, resulting in variation in the expression of the disease. The scoring was therefore based on the presence, and not the degree, of wilting and stunting, or the size of the cankers. Plants free of all these symptoms were rated resistant. The coefficient of variation for vascular discoloration on individual plants was calculated to be 50%, which in part may be explained by the histopathology of the host.The virulent isolates cm 21 caused death of seedlings resistant to isolate H. However, cultivars resistant to isolate H in the seedling stage did not decrease in fruit weight as compared to susceptible cultivars when inoculated with isolate cm 21 at anthesis.

The effect of 4 storage treatments on seed yield components of 3 onion inbreds

Abstract Onion bulbs of 3 inbred lines were stored during the winter in 4 different storage temperature regimes. Traits directly and indirectly associated with seed production were studied the following summers. The inbred lines differed in their responses and many traits were affected by the storage treatments. The storage treatment of 10°C for 12 weeks followed by 2° C for 12 weeks resulted in a significantly higher seed yield than did storage at 2° C throughout the entire period. Inbred 2399 had a higher seed yield than the other inbreds. Associated with high seed yields of 2399 was early flowering, a high number of leaves/bulb, tall seed stalks and a high number of florets/bulb.

Investigations on F1 and F2 hybrids between Brassica oleraceae Var. Acephala and Raphanus sativus

A cross was made between B. oleraceae var. acephala and R. sativus. The use of a piece of cotton soaked with the growth regulator, N-m-tolyphthalamic acid at 100 ppm and attached to the pedicel at the time of pollination resulted in set of several pods with one viable seed. The hybrid kale x radish appeared vegetatively intermediate between the parents except for the flower color which resembled the radish. The F1 plant propagated asexually and maintained under screen isolation cages with pollinating insects for a period of four years yielded only one viable F2 seed. The single F2 plant obtained, an allotetraploid, failed to yield any fertile seeds through selfing. Backcrossing of this F2 plant to the radish has yielded two seeds.

A greenhouse method for screening lettuce for resistance to Sclerotinia sclerotiorum.

Abstract Agar blocks colonized by Sclerotinia sclerotiorum, causal agent of lettuce drop, were used as inoculum in screening for resistance to this pathogen in the greenhouse. Since the degree of resistance to the pathogen among cultivars varied with the time observed after inoculation, resistance was assessed by the number of days for 50% of the plants of each cultivar to die, as well as the number of plants that died. The cultivars ‘PI (Plant Introduction) 250427’, ‘Taiwan’, ‘PI 251790’, ‘PI 255568’, ‘MSU 73-44’ and ‘Bibb’ were found to have a higher level of resistance to S. sclerotiorum than the cultivar ‘Grand Rapids’ at 12 or 15 days following inoculation.

Studies on the inheritance of resistance to tobacco virus in the tomato

Results obtained from 9 weeks of observation of inoculated plants from the tomato cross Plant Introduction (P.I.) # 235673. Fireball suggest that in this cross genetic control of inheritance of resistance to Tobacco Mosaic Virus (TMV) to be multigenic. Virus assay made from inoculated plants of parents and progenies suggested that resistance depended upon the suppression of virus multiplication. For the susceptible parent. Fireball symptoms appeared 14 days after inoculation while the resistant parent ranged from 35 to 49 days. Virus concentration for Fireball was much higher and remained constant during the period while for P.I. # 235673, it was lower and less concentration was required for symptoms to appear as the plants grew older.