Intercropping sorghum and grasses during off-season in Brazilian Cerrado

Sorghum (Sorghum bicolor (L.) Moench) may be harmlessly intercropped with Urochloa species during the off-season in the Brazilian Cerrado. At the end of the sorghum cycle, forages can be used for straw production for soybean (Glycine max L.) as the summer crop. This study aimed to evaluate sorghum cultivated during the off-season, intercropped with palisade grass (Urochloa brizantha cv. 'Marandu' (Hochst. ex A. Rich). R. D. Webster) and Congo grass (Urochloa ruziziensis (R. Germ. and Evrard) Crins) in two row spacings (0.5 and 0.7 m) for their effect on plant growth, dry mass production, sorghum yield and soybean grain yield. The experiment was a randomized block design: a 3 × 2 factorial scheme, with three levels of intercropping (palisade grass, Congo grass or sole cropping) and two levels of row spacing (0.5 or 0.7 m) with four replicates. Several physiological growth indexes were estimated from 10 to 60 days after emergence (DAE), including dry matter production and sorghum agronomic performance. Sorghum accumulated 0.22 g of dry matter d-¹ at 10 to 60 DAE, and was not affected by intercropping. The dry mass gain of forages (0.04 g d-¹ on average) was not affected by sorghum either. Higher sorghum grain yield (2,922 kg ha-¹) was observed under the 0.5-m row spacing when compared to the 0.7-m spacing. The results indicate that palisade or Congo grass may be used as companion crops for sorghum with no grain yield loss, be it to improve soybean grain yield, soil cover or integrated crop systems, aiming at sustainable intensification.

Air layering in Caryocar brasiliense - effect of stem diameter / Alporquia em pequizeiro - efeito do diâmetro do caule

Seed propagation of pequizeiro (Caryocar brasiliense) has many disadvantages, including low germination rates and high genetic variability of the resulting plants. Therefore, vegetative propagation techniques, such as the air layering process, are potentially important for this species. This study evaluated the effects of stem diameter and parental plant on the air layering efficacy of pequizeiro. The air layering process was carried out in mid-December 2019, in the following stem diameters: less than 15 mm; 15-19 mm; 20-24 mm; 25-29 mm and above 29 mm. The treatments comprised four replicates of 10 air layers. After 3 months, the percentages of survival, callus formation and rooting were evaluated, in addition to the rooting vigor. The percentages of survival and callus formation observed in the air layering, regardless the parental plant, were higher than 85%, showing the high potential of this technique in the propagation of pequizeiro. The callus differentiation rate in roots varied between the parental plants. Considering the evaluated parameters, stem diameters ranging from 20 to 24 mm are the most suitable ones for the air layering process in pequizeiro. These results indicated the high potential of the air layering technique for the commercial propagation of pequizeiro.

A propagação seminal de pequizeiro acarreta grande variabilidade na taxa de germinação e no genótipo das mudas produzidas, mostrando a necessidade do desenvolvimento de técnicas para a propagação vegetativa dessa espécie, como a alporquia. Os objetivos deste estudo foram avaliar a eficácia da alporquia, bem como o efeito do diâmetro do caule e da planta-mãe na sobrevivência, no calejamento e no enraizamento de alporques de pequizeiro. O processo de alporquia foi realizado em meados de dezembro de 2019, nos seguintes diâmetros de caule: inferior a 15 mm; 15-19 mm; 20-24 mm; 25-29 mm e superior a 29 mm. Os tratamentos foram testados em quatro repetições de 10 alporques. Após três meses, avaliaram-se as porcentagens de sobrevivência, de calejamento e de enraizamento, além do vigor de enraizamento. As porcentagens de sobrevivência e de calejamento nos alporques, independentemente da planta matriz, foram superiores a 85%, mostrando o grande potencial dessa técnica na reprodução de pequizeiro. A taxa de diferenciação de calos em raízes variou entre as matrizes. Considerando os parâmetros avaliados, diâmetros de caule de 20 a 24 mm são os mais adequados para a alporquia em pequizeiro. Esses resultados indicam o potencial da técnica de alporquia para a produção comercial de mudas de pequizeiro.