Subsolagem em um LATOSSOLO AMARELO coeso de Tabuleiro Costeiro e conseqüências no comportamento do cultivar Tangor Murcote (etapa II)

Abstract

Brazil is the biggest world citrus producer and the states of São Paulo the biggest national producer followed up by the States of Sergipe and Bahia. In Bahia, about 90% of the citrus cultivated area are located on the littoral band where compact Tableland soils predominates (area of smooth topography from flat to slightly). The limitation of physical (elevated resistance to penetration, deficiency of aeration and Water availability), and chemical nature (elevated acidity and low availability of nutrients) common in the main soils (Yellow Latossol and Yellow Argissol) of the Sea Coast Tableland ecosystems hamper agricultural production, being necessary the search of techniques and management that render sustainability to agriculture in the ecosystem. The goal of this work was to evaluate the effect of several ways of subsoiling in a compact Yellow Latossol of the Coastal Tableland and the consequences in the development of a Tangor Murcote( Citrus reticulata Blanco X Citrus sinenses Osbeck) cultivar. Specifically, there was the intention of evaluating the soil resistance to the penetometer under growing disturbance caused by subsoiling six year before. Also, the consequenceson plant growth (roots and shoots), productivity, fruit drop, and fruit average weight was investigated. Chemical soil and leaves analysis were done to evaluate plant nutritional status. The experiment was installed at the Fazenda Lagoa do Coco, locatedin the city of Rio Real, North Littoral of the State of Bahia, in the area of Coastal Tableland, at 182 above sea level and 11°34’25” S, and 37°52’58” W. The experimental design was Complete Randomized Blocks, with five treatments and six repetitions: T1- plowing and harrowing (conventional); T2- One line subsoiling on the planting line; T3- One line subsoling crossed on the planting hole; T4- Three line subsoiling crossed on the planting hole. T5- Three line subsoiling crossed on the planting hole. It Was concluded that the caused disturb by subsoiling the compact layer improve soil structure, increasing the circulation of air, water, and nutrients. This favor plant development and possibly plant longevity (What can be only know whit greater research time). The best treatments, in absolute numbers, were treatment 4 and 5, in relation treatment 1 (no subsoiling), the othrs treatments increased plant growth, yield, and fruit average weight and decreased fruit drop. For the variables studied the results were in the following order: Plant height: T1= 100%, T2= 102%, T3=106%, T4=111%, T5=107%; Canopy diameter: T1=100%, T2=103%, T3=104%, T4=117%, T5=109%; stem diameter: T1=100%, T2=101%, T3=103%, T4=107%, T5=108%; Fruit/ha (Season 2001/2002): T1=100%, T2=132%, T3=133%, T4=163%, T5=146%; Fruit/plant/ha: T1=100%, T2=145%, T3=159%, T4=198%, T5=178%; Fruit abscission/ha: T1=25%, T2=18%, T3=10%, T4=9%, T5=8% (fruit drop in treatment 1 was approximately three times that of treatment 4 and 5, suggesting that subsoiling improve fruit duration on the tree). Fruits/ha (Season 2004/2005) T1=100%, T2=150%, T3=233%, T4=266%, T5=344%; Fruit weight/ha: (Season 2001/2002): T1=100%, T2=170%, T3=264%, T4=317%, T5=407%. Fruit average weight/ha (Season 2001/2002): T1=100%, T2=107%, T3=110%, T4=112%, T5=120%. The growth of plant root system in relation to soil preparation is shown in the text by photos. The nutritional status of the plants did not interfered in the results.