José R. Bautista-Aguilar, Lourdes G. Iglesias-Andreu, Jaime Martínez-Castillo, Marco A. Ramírez-Mosqueda, and Matilde M. Ortiz-García
Vanilla planifolia Jacks. is a species of great economic importance, since vanillin, a compound highly valued in the food and pharmaceutical industry, is extracted from its pods. This species is in the category of special protection, so it is important to take actions for its conservation and to maintain the genetic stability of the conserved germplasm. An adequate way to achieve this is through the minimal growth in vitro conservation techniques. The present work aimed to establish an in vitro conservation protocol for vanilla germplasm that allows the genetic stability of the conserved material. For the establishment of the minimal growth in vitro conservation protocol: two concentrations of basal Murashige and Skoog (MS) medium (50% and 100%), two incubation temperatures (4 and 22 °C) and two concentrations of abscisic acid (ABA) (3 and 5 mg⋅L−1) were evaluated. To evaluate the genetic stability of the germplasms used in this study (cultivated, wild, and V. insignis morphotypes) by analyzing the profiles of molecular markers SSR (simple sequence repeats) and ISSR (inter simple sequence repeats). The MS medium (100%) supplemented with 3 mg⋅L−1 of ABA and incubated at 22 °C, was the best treatment for the in vitro conservation of Vanilla spp. Compared with the control treatment, it allowed us to obtain smaller shoots (1.17 × 0.17 cm), which showed high genetic stability, given by the low percentages of polymorphism detected in morphotypes cultivated and wild (SSR 0%, ISSR 2%) and V. insignis (SSR 0%, ISSR 0%). We conclude the usefulness of the established protocol to conserve the genetic variation of the evaluated Vanilla germplasm.
Hsuan Chen and Dennis J. Werner
Eastern redbud (Cercis canadensis L.) is a commonly used small landscape tree. Compact growth, purple leaf color, and weeping architecture are three popular ornamental phenotypes. Inheritances of weeping architecture and purple leaves have been reported previously. Inheritance of compact growth habit and its genetic linkage with the weeping and purple leaf genes have not been reported. In the present research, the inheritance of compact growth derived from ‘Ace of Hearts’ was explored in the F1, F2, and reciprocal backcross families resulting from the controlled hybridization of ‘Ruby Falls’ (normal growth/weeping architecture/purple leaf) × ‘Ace of Hearts’ (compact growth/nonweeping architecture/green leaf). All 27 F1 individuals were nonweeping, green-leaved, and noncompact. A total of 572 F2 progeny were obtained, and subsequent analysis of segregation revealed a single recessive gene controlled compact growth habit. Analysis of reciprocal backcross families confirmed this result as well. Weeping architecture and purple leaf color were also controlled by single recessive genes, confirming findings presented in previous studies in another redbud family. No linkage between the three genes was detected. This research is the first to report the inheritance of compact growth in eastern redbud and confirms independent assortment between the compact, purple leaf, and weeping genes.
Tengfei Pan, Peibin Huang, Jianwen Ye, Dongming Pan, Zhijun Fu, Heli Pan, Zhixiong Guo, Wenqin She, and Yuan Yu
Luis A. Rivera-Burgos, Emily J. Silverman, and Todd C. Wehner
Stephanie J. Walker, Paul Funk, Israel Joukhadar, Tom Place, Charles Havlik, and Bradley Tonnessen
Emma K. Dawson, George E. Boyhan, Tim Coolong, Nicholas T. Basinger, and Ryan McNeill
Along with the many known benefits of cover crops, they may be an effective ecological weed management strategy in low-input agriculture. This research aimed to determine the effect of cover crops, combined with reduced-tillage and nitrogen inputs on sweet corn (Zea mays) yield and weed communities. During the 2-year study, the impact of the cover crop on yield varied. Yield within the no-till conventional treatment plots was not significantly different from the conventional treatment [6844 and 7721 lb/acre (P = 0.592)] in year 1 but differed in year 2 (P = 0.003). Weed density and experimental area covered by weeds were not significantly different between conventional and no-till conventional treatments. Multivariate analyses showed associations between specific weed species and management practices. Weeds were greatest in no-till organic treatments, and they had significantly lower yields, suggesting additional weed control beyond cover crops may be necessary for organic vegetable systems under reduced tillage.
Toktam Taghavi, Alireza Rahemi, Reza Rafie, and Maru K. Kering
Rapid multiplication of turmeric (Curcuma longa) by micropropagation is needed to produce a continuous source of uniformly sized, high-quality, and disease-free plantlets. Three in vitro experiments were conducted to optimize the medium by evaluating nine media and a full factorial combination (matrix) of two plant growth regulators for direct organogenesis of ‘Hawaiian Red’ turmeric. Two experiments evaluated the media, and the third studied the plant growth regulator matrix. As a result, Driver and Kuniyuki walnut (DKW), Murashige and Skoog (MS), and broadleaf tree basal (BLT) media performed better than woody plant media [Lloyd & McCown woody plant basal medium (L&M), and McCown’s woody plant basal salt mixture (McCown)] for shoot and root formation. The multiplication rate was 18 plants per explant in DKW with 1 mg⋅L−1 6-benzylaminopurine (BAP) and 0.1 mg⋅L−1 1-naphthaleneacetic acid (NAA). After transferring the plants to an ex vitro environment, the survival rate was 97%, and 30% higher than previously reported. DKW produced the highest number of plantlets (with shoots and roots), and BLT produced fewer plants with higher biomass. In the MS media, higher BAP to NAA ratio (2.5 to 0.1 mg⋅L−1) produced the most significant number of shoots; however, the lowest concentration of BAP and NAA (0.1 mg⋅L−1 of both) produced the highest number of rooted plantlets. There are two recommendations for tissue culture of ‘Hawaiian Red’ turmeric. To produce the highest number of plantlets, one should use the higher BAP to NAA ratio (2.5 mg⋅L−1 BAP and 0.1 mg⋅L−1 NAA) for shoot proliferation and then transfer the explants to the root initiation media. However, to reduce the number of subcultures, the explants can be grown in the lowest concentration of both BAP and NAA (0.1 mg⋅L−1) to induce both shoot and root. Although, the number of plantlets (with roots and shoots) will decrease in this method, there is no need for subsequent subcultures and changing of the plant growth regulator combinations.
James M. Orrock, Brantlee Spakes Richter, and Bala Rathinasabapathi
Tea (Camellia sinensis) is a promising new specialty crop for production in Florida. However, few data exist on the establishment phase of tea plantings in this environment and on how early growth parameters may predict yield potential. We tested seven accessions of tea grown under field conditions in north-central Florida for leaf yield and growth parameters—namely, pruned biomass, trunk diameter, trunk height, trunk width, trunk height × width, and canopy area—in the second and third years after planting. Our analyses indicated that the accession Fairhope performed best overall. Pruned biomass and trunk diameter were the best predictors for leaf yield. The harvested leaves produced good-quality black tea, with caffeine levels comparable to commercially available tea. These data indicate that nondestructive measurements of growth can be useful to assess yield potential of tea, and that regionally adapted tea accessions can be identified during the establishment stage.