Chilean Journal of Agricultural Research

ABSTRACT The intensification of cattle post-weaning phase in tropical pastures depends on supplementation strategies. The objective of this study was to assess the effect of increasing levels of concentrate supplement on the intake, apparent digestibility of nutrients, feeding behavior, and performance of Girolando steers on tropical pasture during the post-weaning phase in the rainy season. Forty uncastrated male Girolando steers, initially weighing 266.62 ± 32.95 kg and aged 11 mo, were allocated into four concentrate supplement levels: 0.2%, 0.3%, 0.4%, and 0.5% body weight. The steers grazed on Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster ‘Marandu’ pasture. The intakes of supplement DM, non-fibrous carbohydrates (NFC), and total digestible nutrients increased linearly (P < 0.05) with the level of supplement offered to the steers. In a similar response, the apparent digestibility of DM and NFC from the diet also rose linearly (P < 0.05). Grazing time, total feeding time, and total chewing time decreased (P < 0.05) with the increasing levels of concentrate supplementation. In contrast, the time expended on feeding at the trough, biting rate, and the time taken to ruminate each cud increased (P < 0.05) with the supplementation level. Final body weight and average daily gain increased linearly (P < 0.05) with increasing concentrate supplementation. We recommend supplying concentrate supplement at a level of 0.5% of the body weight of steers on tropical pasture during the post-weaning phase in the rainy season.

ABSTRACT The availability of hot pepper (Capsicum frutescens L.) hybrid varieties is limited compared to those in chili, bell or sweet pepper hybrid. Heterosis, heterobeltiosis, and reciprocal are critical indicators in F1 hybrids, valuable for developing hybrid varieties. This research aimed to evaluate both phenotypic and genotypic changes in F1 hybrids from single cross-hybridization. The study observed 53 phenotypic characteristics encompassing morphological (plant, leaves, flowers, and fruits), four production-related (fruit weight, fruit number per plant, fruit weight per plant, and yield per hectare), and 10 chemical characteristics (proximate, simple sugar, and secondary metabolite). Genotypic changes were analyzed using ten SSR markers. Employing a randomized complete block design, the study included two parents, F1, and reciprocal F1 hybrids, across four treatments with two replicates each. Phenotypic changes were analyzed using ANOVA and comparison test, while genotypic changes were analyzed through cluster analysis. Result indicated heterosis in 12 characters, heterobeltiosis in eight characters, and reciprocal effects in eight characters. Significant improvements were noted in key characteristics such as plant height, fruit maturity, fruit weight per plant, yield per hectare and vitamin C. Genotypic evaluation revealed distinct genetic differences between F1 and its parents, including the reciprocal F1. These phenotypic and genotypic changes suggest that hot pepper could be more productive and of higher quality when developed as a hybrid variety, indicating promising avenue for future breeding programs.

ABSTRACT Soil salinization restricts crop growth and yield, thereby adversely affecting agricultural development. The stage of seed germination is the most crucial and sensitive stage in the plants’ life cycle and is particularly sensitive to saline-alkali stress. We investigated the effects of different hormonal priming agents, namely melatonin (MT), abscisic acid (ABA) and brassinosteroid (BR), as well as the osmopriming agent, calcium chloride (CaCl2), on the germination of wheat (Triticum aestivum L.) seeds under saline-alkali stress. Saline-alkali stress was simulated with the solution of 100 mM NaCl and 50 mM NaHCO3/Na2CO3 (9:1). The results indicated that hormonal priming agents (ABA, MT, or BR) significantly alleviated saline-alkali stress-induced inhibition of wheat seed germination. The germination rate of seeds primed with ABA, MT, or BR increased by 21.0%, 11.0%, and 10.5%, respectively. The seeds primed with ABA, MT or BR showed improved activities of α- and β-amylase under saline-alkali stress, with corresponding increases in starch hydrolysis and soluble sugar content, which contributed to seed germination and embryo growth. Hormonal priming (ABA, MT, or BR) also significantly improved antioxidase activities to alleviate oxidative damage in germinating seeds under saline-alkali stress. Seeds primed with ABA (38.7%), MT (37.0%), and BR (31.3%) displayed lower malondialdehyde (MDA) content than the H2O-primed seeds. The ABA exerted the most significant promoting effect on wheat seed germination under saline-alkali stress. The promotional effect of CaCl2 on seed germination was nonsignificant compared with that of hydropriming. The results offer a theoretical and practical basis for applying seed priming to enhance the saline-alkali tolerance of wheat in production.

ABSTRACT Potato (Solanum tuberosum L.) seed production using the aeroponic system has been widely implemented in Indonesia. However, aeroponic systems in tropical areas such as Indonesia faced obstacles in the form of high wilt attacks caused by the bacteria Ralstonia solanacearum. This research aimed to control R. solanacearum wilt disease in an aeroponic system using various microbes. The research was carried out from September 2022 to January 2023. This research consisted of four stages, namely exploration and isolation of microorganisms, identification of microbial antagonism, testing of in vitro potential microbial antagonism and testing of selected microbial antagonism in the aeroponic system. The nutrients used in the aeroponic system contained R. solanacearum with a concentration of 104 CFU mL-1, while the concentration of the microbial solution used was 108 CFU mL-1. Pseudomonas fluorescence was consistently the best microbe both in vitro and in aeroponics, whereas Bacillus subtilis could only overcome wilt in vitro and could not overcome wilt in aeroponic system. Pseudomonas fluorescence required 5 min soaking time and could increase wilt with increasing soaking time. The consortium between B. subtilis and P. fluorescence with 10 min soaking time could overcome wilt by 85% and increase the number of tubers and tuber weight by 79% and 85%, respectively, so this prospective microbial consortium could be applied to aeroponic systems environmentally friendly in tropical areas with high R. solanacearum opportunities.

ABSTRACT The assembly of cayenne pepper (Capsicum frutescens L.) cannot be separated from the direction of qualitative character development. This is based on the role of qualitative characters in determining nutritional content and market segments. Therefore, the analysis of qualitative characters in the F4 multiple cross cayenne pepper population needs to be done in determining the direction of line development in the next generation. The purpose of this study was to identify the inheritance pattern of qualitative traits and genotype grouping from a population of F4 multiple cross lines. The research was conducted at the Experimental Field of Hasanuddin University, Makassar, Indonesia. The study was designed with the concept of observation on 90 F4 multiple cross chili lines and three parental cultivars (Dewata F1, Bara and Ungara). Observations focused on 10 qualitative characters. The analysis showed that there are two types of diversity in this population, namely centralized diversity and distributed diversity. Centralized diversity consists of leaf color, book color, leaf shape, canopy density, stem color, fruit shape, and fruit tip shape. In contrast, characters that have a diverse distribution are crown color, young and old chili fruit color. The distribution results show three main groups, namely the Dewata-Bara group (27 genotypes), the Ungara group (16 genotypes) and the rest are groups outside of these two groups. Based on the whole study, the results of this evaluation are recommended as a consideration for the selection of F5 lines in supporting the direction of releasing chili cultivars from multiple cross.