The Effects of Light and Temperature on Germination and Growth of Luffa aegyptiaca

Abstract

The effects of light and temperature on the germination and growth of Luffa aegyptiaca were investigated both in the laboratory and in the field. The seeds germinated in both darkness and light but germination was better in the light.At constant temperatures germination was best at 21°C, while alternating temperatures of 21 and 31°C and 15 and 41°C caused higher germination than the most favourable constant temperature. Constant temperatures of 15 and 31°C and alternating temperatures of 21 and 41°C resulted in very low germination, whereas no germination occurred at 41°C and at alternating temperatures of 31 and 41°C. Soil depth caused only a delay in seed germination, as it did not affect the total germination.High temperature and high light intensity resulted in good seedling growth in terms of dry weight, leaf area and relative growth rate. High temperature and low light intensity caused increased plant height and high shoot weight ratio, both of which manifested in seedling etiolation. They also caused high leaf area ratio. Under low temperatures, irrespective of light intensity, growth was generally poor, but it was significantly poorer under low light intensity, which also caused high root weight ratio. High light intensity was principally responsible for high leaf weight ratio. The results help to explain the abundance of the species in newly cleared areas in Lagos and its environs.

Germination and Growth of Celosia Cristata L., Under Various Light and Temperature Regimes

“…Like some other tropical species, Celosia showed considerable preference for light in germination (Njoku, 1959;Edwards 1975;Okusanya 1978;1979). With Celosia growing in the open, the seeds would naturally be subjected to high light intensity and high temperatures-thermoperiod of 35-C day and 24-C night with a mean of 29.5 C.…”

“…Edwards, personal commun. ), showed a remarkable tolerance of high temperature, 21-41 C, in contrast to Luffa aegyptiaca, 15-31 C (Okusanya, 1978) and some temperate species (Rozema, 1975).…”

“…Shading has been found to cause reduced growth in tropical species (Njoku, 1960;Wadsworth and Lawton, 1968;Okusanya, 1978) as well as in nontropical species (Blackman and Wilson, 1951;Evans and Hughes, 1960;Oguntala, 1974). Differences have also been observed in the form and size of Celosia depending on whether it grows in the open or under shade.…”

“…This paper, which is the report of an investigation carried out to quantitatively determine I Received for publication 4 Germination experiments-Methods-Germination methods follow those described in Okusanya (1978), in which seeds were germinated in petri dishes with two layers of Whatman filter paper moistened with distilled water. There were four replicates of 50 seeds for each treatment and germination was recorded every five days for 30 days.…”

Escarificação ácida, temperatura e luz no processo germinativo de sementes de Senna alata (L.) Roxb

“…A espécie é considerada medicinal possuindo propriedades antibacterianas, antifúngicas e antiinflamatórias (Abatan, 1990;Palarrichamy & Nagarajan, 1990;Bhaskar & Nagarajan, 1991), diurética e laxante, utilizada como matéria prima para produção de medicamentos destinados a tratar de anemia, fígado, malária e pano-branco. Apesar das propriedades terapêuticas, deve ser ministrada com cuidado, pois é também suspeita de ser tóxica e abortiva (Lorenzi, 2000).…”