Manejo sustentável de irrigação utilizando hidrogel no cultivo de calendula officinalis l Sustainable irrigation management using hydrogel in the cultivation of calendula officinalis l

This work aimed to characterize physically and physiologically buffelgrass seeds collected in different municipalities located in the semiarid region of Bahia and at different positions in the panicle. At each site, two hundred mature, whole panicles were collected when seeds were naturally falling. A 5 × 3 factorial in a completely randomized design was used. Factors were five municipalities where seeds were collected and three positions within the panicle (bottom, middle and top portions), with four replicates of 50 seeds for each treatment. Moisture content, dry seed weight, electrical conductivity, germination percentage, germination speed index and emergence speed index were assessed. Data were tested by analysis of variance and Tukey test at 5% of significance level. Soil and climate conditions of each region affect the physiological quality of buffelgrass seeds. Seeds located in bottom and middle portions of the panicle are more vigorous than seeds located in the top portion. The municipality of Poções has better conditions for yielding buffelgrass seeds of better quality than the remaining municipalities.

Iron mining tailings have limitations for plant growth and development due to low fertility, coupled with great restriction of physical characteristics such as low water retention, high density, and lack of structure. This study aimed to evaluate whether different irrigation depths applied to Xaraés grass grown in mining tailings influence its yield and bromatological aspects. The experiment was carried out in a completely randomized design with five irrigation depths (40, 60, 80, 100, and 120% of the crop evapotranspiration), two additional treatments consisting of grass grown in tailings with soil conditioner and in natural soil, and three repetitions. Forage dry mass, plant height, leaf: stem ratio, as well as neutral detergent fibre, acid detergent fibre, crude protein, and mineral matter content, were evaluated during four cutting cycles. Xaraés grass could establish and produce forage despite cultivation limitations in iron mining tailings, which are due to their properties. Irrigation depths showed positive and linear effects on Xaraés grass dry matter yield and heights of plants grown in iron mining tailings. The soil conditioner has potential for use in pasture cultivation in iron mining tailing.

The collapse of the Fundão dam in Brazil caused one of the biggest environmental disasters. One of the challenges was how to manage the tailings so that affected areas could be reused. This study aimed to verify whether applying different irrigation depths to Xaraés grass grown with iron mining tailings would affect grass shoot and root dry masses. The experiment was set up in a randomized design with five irrigation depths (40%, 60%, 80%, 100%, and 120% of crop evapotranspiration) and two additional treatments (grass grown in tailings with soil conditioner, and grass grown in natural soil), each with three repetitions. The grass was cut four times, and the shoot dry mass was evaluated after each cut, while the root dry mass was evaluated at the end of the experiment. Our results showed that irrigation depths had a positive linear effect on shoot dry mass and an exponentially increasing effect on root dry mass, with the highest averages in the treatment applying 120% of crop evapotranspiration. This study showed that even in adverse conditions, Xaraés grass was able to grow and develop well.

RESPOSTA DO FEIJÃO-CAUPI A INOCULAÇÃO COM ESTIRPES DE BRADYRHIZOBIUM E ADUBAÇÃO NITROGENADA EM CULTIVO PROTEGIDOA inoculação de sementes de feijão-caupi com bactérias fixadoras de nitrogênio atmosférico pode ser uma alternativa de manejo mais sustentável. Neste estudo, objetivou-se avaliar os efeitos da inoculação e doses de N sobre características do feijão-caupi, em cultivo protegido. Utilizou-se o delineamento experimental em blocos ao acaso, arranjados em esquema fatorial 4 x 4, com quatro fontes de N, caracterizadas por três estirpes (BR 3262, BR 3267 e BR 3299) e uma testemunha sem inoculação e sem N mineral, e quatro doses de adubação nitrogenada (0, 20, 40 e 60 kg ha-1). As características avaliadas foram: altura de plantas, massas secas da parte aérea, da raiz e de toda a planta, número de nódulos, massa seca de nódulos e eficiência relativa dos tratamentos. No tratamento inoculado com a estirpe BR 3267, a massa seca da parte aérea, raiz e de toda a planta aumentaram, com doses crescentes de N até 30 kg ha-1. Entretanto, a nodulação foi inibida, com o aumento da dose de N. A eficiência simbiótica da estirpe BR 3262 foi semelhante à da testemunha, sendo as demais inferiores, indicando que a população nativa de rizóbios, por si só, é capaz de suprir a demanda da planta.Palavras-chave: Bradyrhizobium; fixação biológica de nitrogênio; nutrição mineral; Vigna unguiculata (L.) Walp. ABSTRACT: Inoculating cowpea seeds with atmospheric nitrogen-fixing bacteria may be a more sustainable management alternative. The objective of this study was to assess the effects of inoculation and N fertilizer rates on characteristics of cowpea grown in greenhouse. A randomized complete block design was used. Treatments were laid out in a 4 x 4 factorial experiment consisting of four N sources: three inoculant strains (BR 3262, BR 3267 and BR 3299) and a non-inoculated control without mineral N supply; and four N fertilizer rates (0, 20, 40 and 60 kg ha-1). The following characteristics were evaluated: plant height, shoot dry weight, root dry weight, total dry weight, number of nodules, nodule dry weight, and relative efficiency of treatments. For the treatment inoculated with strain BR 3267, shoot dry weight, root dry weight and total dry weight increased with increasing N rate up to 30 kg ha-1. However, nodulation was inhibited with increasing N rate. The symbiotic efficiency of strain 3262 was similar to that of the control and lower than the remaining strains, indicating that the indigenous population of rhizobia, by itself, is able to meet the plant’s N demand.Keywords: Bradyrhizobium; biological nitrogen fixation; mineral nutrition; Vigna unguiculata (L.) Walp.