Crop Physiology in Relation to Agronomic Management Practices

Abstract

This chapter describes the physiology of kenaf from seed germination and root development till the effects of water and nutrients stress on grown plants. Review on kenaf agro-physiology of experiments carried out worldwide are presented and discussed mainly at the canopy and whole-plant level with the aim to help producers to make decisions and planning of production. However, few literature reports experimental results on the physiology of this multipurpose crop especially in terms of assimilation rate and its relation with environmental and agronomic factors. Knowledge on gas exchange rate and stomatal conductance may be a key support in understanding the physiology of Kenaf in terms of water requirements, its ability of light conversion into carbonaceous molecules influencing crop production potential and, indirectly, the carbon sequestration activity. In kenaf seedling development takes place when temperatures are higher than 10 °C, supporting the idea that kenaf is a macrothermal plant and optimal sowing has to be carried out during springsummer, depending on the area of cultivation. Kenaf is very sensitive to reduced soil water availability, however, under moderate water stress conditions the crop maintains root development while reducing final biomass yield. Recent studies from Greece and Italy showed that even though kenaf uses CO 2 , solar radiation, water, and nitrogen less efficiently than C 4 crops its assimilation rates can reach 50-58 kg of CO 2 ha −1 h −1 . However, great differences in terms of net photosynthesis have been reported by various authors, which may be related to the different environmental variables and agronomic managements during field and controlled experimental environments, such as air temperature, light intensity, water supply, nutrients availability, relative humidity, wind, cultivar, plant density, and soil type. Similar results were reported in the literature regarding stomatal conductance and transpiration rates. In experiments carried out during the night, stomatal conductance and transpiration rate determined