Plant growth analysis of maize (Zea mays L.) inter-cropped with cassava (Manihot esculentus Cranz)

2000

English

Growth analysis was used in an investigation as an aid in the quantitative interpretation of plant growth of different stands of two maize (Zea mays L.) varieties (‘Dorke' and ‘Dobidi') and two cassava varieties (‘Bosome Nsia' and ‘Ankra') established as intercrops in experiments at Fumesua (1986) and Kwadaso (1987) in Kumasi (6° 43' N 1° 36' W) The trials were conducted in a randomized complete block design with a 24 factorial arrangement of four main factors. There were four blocks per trial. In Trial 1 (Fumesua 1986 first (major) rainy season), the treatments in the intercrop were maize variety (‘Dorke' and ‘Dobidi'), maize density (20 000 and 40 000 plants/ha), cassava variety (‘Bosome Nsia' and ‘Ankra'), and maize fertilization (45 and 180 kg/ha N). In Trial 2 (Kwadaso 1987 second (minor) rainy season), the treatments in the intercrops were similar to those of 1986 at Fumesua, except that the maize fertilization treatment was replaced by a cassava density treatment at 10 000 and 20 000 plants/ha. The use of this analysis to detect differences in growth between years for one variety and between varieties in one year was essential in this analytical approach to crop studies. The investigations pointed out the genotypic and phenotypic differences in growth between varieties and their relationship to economic yield. Leaf area development (LAD) was important in the accumulation of dry matter and led to higher grain yield in maize. As expected, the early-maturing variety (‘Dorke') showed a pronounced decline in leaf area towards the end of the growth cycle, while in the full-season variety (‘Dobidi') this decline was less pronounced, resulting in the production of more dry matter late in the growth cycle. A higher peak of leaf area could not alone account for the estimated 20 per cent higher grain yield of ‘Dobidi' over ‘Dorke'. Leaf longevity estimated by the values of LAD calculated seemed to have an important influence on yield. The comparisons made indicated that for intercropped maize the magnitude of the shoot dry weight differences between varieties did not relate to grain yield differences. Growth rates did not relate directly to yield either. Important factors that were not estimated but might have contributory effects appeared to be the duration of the grain-filling period and photosynthetic rates which prevailed during the period. All the growth functions declined significantly and rapidly as the plant matured, suggesting a progressively declining rate of dry matter increase.

Asafu-Agyei, J. N.; Ohemeng-Dapaah, S.; Osafo, D. M.