Ivonete Alves Bakke

Taxa de decomposição da serapilheira e atividade microbiana em área de Caatinga

Objetivando avaliar a decomposicao da serapilheira e a atividade microbiana em area de Caatinga preservada, conduziu-se um experimento na Reserva Particular do Patrimonio Natural Fazenda Tamandua, em Santa Terezinha, Estado da Paraiba. A taxa de decomposicao foi determinada com o uso de sacolas de nailon, contendo 30 g de serapilheira, que foram dispostas na superficie do solo em setembro de 2003, sendo retiradas 20 sacolas mensalmente ate setembro de 2005. O material coletado foi seco em estufa e pesado para avaliar a perda de peso em relacao ao peso inicial. A atividade microbiana foi estimada mensalmente pela quantificacao do dioxido de carbono (CO2) liberado no processo de respiracao edafica, a partir da superficie do solo, e capturado por solucao de KOH. A perda de peso da serapilheira, apos um ano, foi de 41,19% e, apos dois anos, foi de 48,37%, evidenciando uma decomposicao mais acelerada no primeiro ano. A analise dos dados mostrou a influencia da estacao do ano na decomposicao de serapilheira e da temperatura na atividade microbiana.

Nutritional value of silk flower hay for lambs

It was evaluated four levels of silk flower (Calotropis procera S.W.) hay (SFH) as a substitute of sorghum (Sorghum bicolor) hay (SBH) in diet for lambs. Nutritional value of silk-flower hay was determined based on aparent digestibility and on metabolic, productive and economical performance of Santa Ines lambs. It was used twenty-four castrated males at 15.72 ± 1.92 kg body weight randomly distributed in four diets with silk-fklower and sorghum hay ratios (100:0, 66:33, 33:66, 0:100), and supplemented with a concentrate mixture based on 50% roughage:50% concentrate (weight/weight). Increase in the levels of silk-flower hay in the diet reduced weight gain and nutrient intake and it increased feed conversion and digestibility coeficients of all the nutrients. Nitrogen balance was similar in all levels of silk-flower hay, although there was a tendency of reduction in nitrogen retention at levels 66% and 100% of silk-flower hay. At the levels 0 and 33% of silk-flower hay in the diet, dry matter ingestion (170 and 180 g/day), daily average weight gain (84 and 89 g/kg0.75) and feed conversion (4.99 and 5.02) were satisfactory. Silk-flower hay can represent up to 16.5% of the total food ingestion or 33% of the roughage in diet for lambs.

Enxertia da faveleira (Cnidoscolus phyllacanthus) sem espinhos

The faveleira tree (Cnidoscolus phyllacanthus Pax et K. Hoffm.) is a forage producing xerophyte of the semiarid region of Northeast Brazil. Forage collection from faveleira plants is difficult due to its caustic thorns, however thornless mutants may be reproduced vegetatively. The present study was carried out in the Seedling Nursery of UFCG, in Patos-PB, to develop a protocol to produce thornless faveleira seedlings by full cleft-grafting using grafts in the dormant or active growth phase on rootstocks in the active growth phase. Dormant grafts were kept refrigerated (+5°C) (T1) or protected from the sun at room temperature (T2), for three days before grafting in December 2003, while active growth grafts were cut off from the tree in December 2003 (T3) or June 2004 (T4), just before grafting. There were 38, 26, 40 and 30 grafts for T1, T2, T3 and T4, respectively. Data collected in successful grafts consisted of rootstock and graft diameter and height, and percentage of successfully sprouted grafts. Rootstock and graft mean diameter (from 10.9 to 11.9mm and from 8.6 to 9.6mm, respectively) and height (from 7.7 to 12.6cm and from 23.7 to 29.8cm, respectively) were similar for all treatments. Grafting was successful in 45, 85, 15 and 33% of the cases for T1, T2, T3 and T4, respectively. Thus, the use of dormant 9mm-thick and 25cm-high grafts, kept protected from the sun at room temperature for three days before grafting, results in the highest rate of success in grafting of thornless faveleira.

REGENERAÇÃO HERBÁCEA EM ÁREAS DEGRADADAS DE CAATINGA ENRIQUECIDAS COM ÁRVORES NATIVAS

Herb recovery was evaluated in degraded Caatinga sites protected from grazing and enriched with native trees, in Patos-PB state, Brazil . Treatments were randomized according to a block design with five treatments (no tree planting –T 0 – or tree planting of three tree species in pure –T 1 = Poincianella pyramidalis , T 2 = Mimosa tenuiflora and T 3 = Cnidoscolus quercifolius – or mixed balanced stands –T 4 ) and five replications of squared-144-m 2 plots with 36 seedlings developing in planting holes enriched with manure and chemical fertilizers, arranged in a 2 m x 2 m grid. Data were collected from September 2008 to October 2009. After this period, natural tree regeneration was still not observed, and tree canopy covered 15 to 49% of the soil and did not affect herb growth and species composition. Initial and final herb cover were 16% and 100%, respectively. The number of dicot herbs increased from five, mainly two Sida species, to 13 species, monocots were represented by one species only (Aristida sp .), and quantity of herb forage reached 3 ton/ha (2:1, dicot:monocot). Adjacent overgrazed plots kept the initial low level of herb cover and species composition. Animal deferment during one year allowed the increase in soil cover and plant diversity in degraded Caatinga sites into which planted tree seedlings established successfully. This management practice could be implemented to avoid further environmental degradation and recover degraded areas.