A new stem-borer of the genus Bucculatrix (Lepidoptera: Bucculatricidae) from Japan, with description of the life history

A new species of bucculaticid moth, Bucculatrix hamaboella sp. nov. (Host plant: Hibiscus hamabo , Malvaceae) is described from Wakayama Prefecture, Japan. The feeding habit of the new species is unique in that: (i) the young larva is a leaf miner forming a long red linear mine but in the later instars the larva becomes a stem borer; (ii) later instar larvae undergo double molts within a cocoonet (molting cocoon); and (iii) penultimate and final instars appear on the surface of the leaf as non-feeding stages. The external non-feeding larvae of B. hamaboella undergoing double molts within one cocoonet are considered to be an abbreviated form of the external feeding instars of other bucculatricids typically making first and second cocoonets, undergoing a single molt within each cocoonet. On the basis of morphological characters, this species is related to the species of Sections I and II (Host: Asteraceae) of Braun (1963), rather than to the species of Section VIII (Host: Malvaceae).     

Changes in water content, sugars and invertase activity in developing seeds of Hibiscus esculentum

Seeds of Hibiscus esculentum were analyzed for growth, in terms of fresh and dry weights, cell size, water content, reducing and non-reducing sugars and acid invertase activity. On the basis of growth analysis seed development is divided into four distinct phases of a) cell division, d) cell elongation, c) dry matter accumulation and, d) maturation. A close parallel with water content and cell size was observed. A peak level of reducing sugars was observed during the rapid elongation growth. The role of invertase in hydrolyzing sugars and its regulation of sink development is discussed.     

Cytogenetic characteristics and the breeding system in six Hibiscus species

Cytogenetic characteristics confirm that Hibiscus acetosella and Hibiscus cannabinus are outbreeders, while Hibiscus asper, Hibiscus physaloides, Hibiscus sabdariffa and Hibiscus surattensis have evolved into inbreeders. The inbreeding species appear to have co-evolved a floral structure in which some anthers abut on the stigma prior to anthesis. Received: 19 February 1999 / Accepted: 17 June 1999     

The potential of hemp (Cannabis sativa L.) for sustainable fibre production: a crop physiological appraisal

Hemp (Cannabis sativa L.) fibre can be used as a raw material for paper and textile production. A comprehensive research programme in the Netherlands has concluded that fibre hemp is a potentially profitable crop, having the right profile to fit into sustainable farming systems. This paper presents an appraisal of the crop physiological characteristics and the agronomic potential of hemp. Parameter values of basic crop physiological characteristics such as light interception potential, radiation use efficiency and dry matter partitioning coefficients are given. The effect of crop management decisions such as cultivar choice, sowing date, plant density, and harvest date on the value of these parameters is discussed. A simple crop growth model was used to assess the yield potential of hemp for the climate of the Netherlands. Calculations made for a non-stressed late-flowering hemp crop sown on 15 April and harvested on 15 September give a stem dry matter yield of 17.1 t ha^-1. The effects of advancing or delaying sowing or harvest date on stem yield were calculated. Crop physiological characteristics of hemp are compared to those of kenaf (Hibiscus cannabinus L.). Radiation use efficiency and dry matter partitioning coefficients of the two crops are similar. Base temperatures for development and growth are lower in hemp than in kenaf. In a temperate climate with cool springs, canopy establishment will be more rapid in hemp than in kenaf. Hemp seems an excellent candidate to fill the niche for an annual fibre crop in a temperate climate.