Vegetative Development and Growing Degree-Days of Tropical and Winter Forages

Abstract

One of the limitations to producing irrigated forages is setting suitable biometric parameters to establish the entrance of animals to grazing areas. Such parameters can be measured or even estimated. Estimates are advantageous for being practical and able to be used for grazing optimization. This study aimed to evaluate the correlation among growing degree-days (GDD), canopy height (CH), leaf area index (LAI), and number of cycle days (NCD) of Guinea grass (Panicum maximum cv. Mombaça) and Bermuda grass (Cynodon spp. Tifton 85) single cropped for one year and overseeded with black oat and ryegrass in the autumn-winter season. The study was carried out from February 2016 to February 2017, and forage crops were sprinkle irrigated. LAI and CH were measured twice a week, at intervals of 3 and 4 days. These parameters were correlated to GDD accumulation at each cutting cycle (CC). All the correlations showed high coefficients in linear fits. For spring-summer cycles, Guinea grass in exclusive cultivation showed the highest averages for CH and LAI, being 102.3 cm and 5.93, respectively. For autumnwinter cycles, when this grass was overseeded, it showed an LAI value similar to that when single cropped, which was of about 5.6. Yet single Bermuda grass presented lower values of LAI (one unit lower) and CH (16.4 cm lower) in the autumn-winter season when compared to that overseeded. The spring-summer cycles of Guinea grass had a duration of 24 days, after which no increase in leaf production was registered.

Thermal time in nitrogen and boron application on irrigated Mombaça grass “Guinea grass”

“…2c and 2d), with 31% less than the daily thermal sum in-season dry. Similar results were observed by [17], with GDD daily accumulations higher in the spring/summer to Guinea grass with 36% (6.6 GDD d -1 in the autumn/winter, and 10.2 GDD d -1 spring/summer).…”

“…2c and 2d), both periods, with values of a similar thermal sum around 290 GDD, the crop reached the cut point or grazing with Luminous Interception Index by maximum leaves (LI = 95%) [6,8,14]. [17], noticed the same resulting to Guinea and Bermuda grasses (Cynodon genus) and concluded that it is possible to obtain correlation among CH, LAI, and GDD.…”

“…4b and 4d). Thus, this could be relating to nitrogen cover fertilization, applied after the forage cut, and the peak of Guinea grass growth that occurs in the first days after the cut [17].…”

Recomendações De Adubação E Desfolha Do Capim Mombaça Para a Região De Carajás – Pará: Eficiência E Efeitos No Solo

“…There is a low efficiency of forage production processes in several properties of the region. According to Siri-Prieto e al (2020), this happens, among other factors, when the management of harvest does not respect the forage plant physiology and when issues of photosynthetically active radiation propitiate the rise of temperature, thermochemical conversion (Siri-Prieto et al, 2020;Dos Santos et al, 2019;Sanches et al, 2019).…”

“…Management techniques, such as defoliation and fertilization, specific for forage cultivated in a region, considering the edaphoclimatic conditions, will enhance production on a property. Therefore, it is necessary to combine strategies of frequency, intensity, and defoliation to achieve production efficiency, and for replacement models of the nutrients exported (Sanches et al, 2019;Dos Santos, 2019).…”