`Lincoln' and `Rondo' pea cultivars (Pisum sativum L. subsp. hortense) were planted at early, midseason, and late dates during 1989–90 and 1990–91 growing seasons. Plant growth analysis data were collected via weekly harvests throughout the growing season. Plant height, leaf area, and shoot dry weight were measured, and LAI, SLA, and SLW were also determined. Derived growth quantities such as RGR, NAR, and CGR were calculated. `Rondo' plants were taller, larger in leaf area, had more vegetative and dry weight, and were earlier in flowering than `Lincoln' plants. Leaf area was not significantly affected by planting date. Optimum LAI was obtained between harvests 7 and 9, which coincides with the time of highest values of NAR and CGR. Significant correlation coefficients were obtained between growth attributes in both seasons, and, in most cases, for all planting dates.
Eleven onion (Allium cepa L.) cultivars were selected to evaluate their yield performance under the arid conditions of the Riyadh area in the Central region of Saudi Arabia during the 1996–97 and 1997–98 growing seasons. The selected cultivars were: Colossal PVP 234, Contessa, Dorado, Red Creole, Ring Master, Rio Sultan, RioTalat, Texas Grano 502, Texas Early Grano 502, Und Grande and Yellow Spanish. Yield (ton/ha) and yield attributes such as bulb diameter, length, weight and dry matter were assessed. Transplants grown in plastic trays for 45 days under greenhouse conditions were transplanted in the field on 7 Jan. 1997 and on 29 Dec. 1997 and harvesting was carried out on 19 May 1997 and on 15 May 1998 for the first and second season, respectively. Significant differences were observed between cultivars and among growing seasons, with significant interaction for yield and bulb weight. The top high yielding cultivars in the first season were Und Grande, Texas Early Grano 502, Colossal PVP 234, Contessa and Dorado. In the second season, Dorado, Red Creole, Contessa, Ring Master and Und Grande outyielded other cultivars. Under the conditions of this study, Contessa, Dorado, Red Creole, Texas Early Grano 502, and Und Grande had the highest yield attributes that made them recommended for growing in the arid regions. The yield and yield attributes of each cultivar will be discussed.
Tubers of three potato cultivars (Norland, Desiree, and Russet Burbank) produced on field-grown plants, greenhouse plants (minitubers), and in-vitro plantlets (microtubers) were kept at 5, 10, and 20°C. Sprouting was recorded throughout a 14- to 22-week storage period. The effect of cultivar, temperature, and tuber size closely followed previous research for field- and greenhouse-produced tubers. For in-vitro produced microtubers, the temperature effect followed an expected pattern, but the cultivar effect was different from that observed for field and greenhouse tubers. Two sprouting indices were developed (sprouting rate index and sprouting ratio index) to quantitatively describe the sprouting characteristics. Correlation coefficients suggest that the “sprouting ratio” method can be an acceptable alternative to the “sprouting rate” method.
A method for micropropagation of Conocarpus erectus through axillary shoot proliferation is presented. Shoot tips were excised from adult donor tree and cultured for 4 weeks on Murashige and Skoog’s (MS) medium supplemented with 3 mg·L−1 gibberellic acid (GA3) to induce sprouting of shoots and formation of axillary shoots. Conocarpus erectus shoots were cultured for 6 weeks on MS medium supplemented with different concentrations and combinations of plant growth regulators (PGRs) and proliferation of the shoots was monitored. The type and concentration of cytokinins applied had a significant influence on shoot proliferation responses. Supplementation with 6-benzylaminopurine (BAP) increased the rate of shoot proliferation compared with other cytokinins. The use of BAP in combination with auxins such as indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) resulted in an increased number of shoots per explant compared with treatment with BAP alone. A combination of 2 mg·L−1 BAP and 0.5 mg·L−1 IBA produced the highest number of axillary shoots (7.8 shoots/explant). The best rooting medium was full-strength MS medium supplemented with 1 mg·L−1 IBA; this treatment yielded 80% rooting with an average of 3.5 roots per plantlet. All regenerated plantlets were successfully acclimatized to greenhouse conditions.