COMMON BEAN YIELD AS AFFECTED BY IN FURROW FILLER LIMING AND NITROGEN TOPDRESSING1

ABSTRACT The use of filler liming in the sowing furrow can improve the chemical characteristics of the soil and, together with nitrogen fertilization, increase common bean yield. The objective of this study was to determine the effect of filler liming of the sowing furrow along with nitrogen topdressing fertilization on the yield of common bean, cultivar Pérola, irrigated by central pivot, in the Cerrado Region. The field experiments were conducted for three consecutive cropping years, in a randomized block design with four replications, in a 2x4 factorial scheme, consisting of two doses of nitrogen topdressing fertilization (zero and 60 kg ha-1 of N) and four doses of filler liming application in the sowing furrow (0, 200, 400 and 600 kg ha-1 of CaCO3). The plant density (PD), number of pods (NP), number of grains (NG), mass of 100 grains (M100) and, grain yield (GY) were evaluated. The use of 60 kg ha-1 of N provided greater M100 and GY. The increase of the filler liming doses in the sowing furrow led to a reduction of the NP. The filler liming dose of 200 kg ha-1 provided higher values of NG and M100, and when combined with the nitrogen topdressing fertilization, improved the GY of the common bean.

Humidity Restriction, High Night Temperature and their Combination, during Post Flowering on Common Bean (Phaseolus vulgaris L.) Canopy and Pod Senescence

Background: Common bean (Phaseolus vulgaris L.) grain filling is vulnerable to drought and heat stress. The objective of the study was to evaluate the effect of humidity restriction, high night temperatures and their combination in common bean.Methods: The plants were grown in pots at maximum field capacity (100% FC) until the grain filling began. Afterwards, maintained until harvest at: 1) 100% FC, 2) 50% FC at ambient day/night temperature (AT), 22.58°C/16.94°C, 3) 100% FC with high night temperature (HNT) 21.47°C and 4) 50% FC with HNT (combined stress). Evaluations included phenotypic assessment using red-green-blue color segmentation in: green (healthy), yellow (senescence) and brown (necrotic). Result: The combined stress in the cv. Rosa Bufa significantly and synchronously accelerated leaves and pods senescence. In contrast, in leaves of cv. OTI, the loss of green color began several days earlier than in pods. The effect of HNT and combined stress depends on common bean cultivar.

Genetic resistance of common bean cultivar Beija Flor to Colletotrichum lindemuthianum

Anthracnose, which is caused by the fungus Colletotrichum lindemuthianum, is one of the most widespread and important diseases of the common bean (Phaseolus vulgaris L.) in the world. The objective of the present study was to characterize the genetic resistance of the Beija Flor cultivar by inheritance and to conduct allelism tests. The inheritance test was conducted in the F2 population derived from the Beija Flor (resistant) x TU (susceptible) cross inoculated with race 2047 of C. lindemuthianum. Furthermore, allelism tests exhibited a fitted segregation ratio of 15R:1S, thereby indicating the independence of the Beija Flor gene from the following previously characterized genes: Co-1, Co-2, Co-4, Co-42, Co-6, Co-12, Co-14, Co-15, and Co-Pe. Based on the aforementioned results, we are proposing the symbol Co-Bf to designate the new anthracnose resistance gene in the Brazilian Andean common bean cultivar Beija Flor. This cultivar is an important source of resistance to C. lindemuthianum that should provide a valuable contribution to the common bean breeding program for anthracnose resistance.