Why regional parties succeed at the sub-national level in India

Existing scholarship in comparative politics has either focused on regionalism or on political and economic decentralisation to explain the growth of regional parties. Using quantitative evidence from India, I show that a hitherto ignored explanation, the level of regional branch autonomy within polity-wide parties, also has a significant impact on the growth of regional parties. When regional branches of polity-wide parties have autonomy, regional parties find it difficult to grow. In contrast, regional parties benefit electorally when regional branches of polity-wide parties are less autonomous. To further account for endogeneity between regional party growth and regional branch autonomy, I use quantitative and qualitative evidence to show that the growth of regional parties is not positively correlated with more regional branch autonomy.

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation’, have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law’, since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation’, have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law’, since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation’, have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law’, since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Early Expression of Apical Control Regulates Length and Crotch Angle of Sylleptic Shoots in Peach and Nectarine

Syllepsis is the predominant mode of branching in young peach and nectarine trees [Prunus persica (L.) Batsch]. Cultivars differ considerably in expression of apical control of sylleptic shoots. This has practical implications regarding tree training. Four cultivars were selected for increasing apical control by the central shoot axis, viz., `Zaigina', `Mayglo', `Fiesta Red' (all nectarines), and `Oom Sarel' (clingstone peach), respectively. Young, actively growing shoots were harvested when ≈300 mm in length, at a time when development of sylleptic shoots (laterals) had begun. Length, crotch angle, and position (as distance from the apex) of the laterals were recorded. When length of the laterals was plotted against their position, two zones were observed. The gradient of length vs. position was shallower in the distal than in the proximal zone. Autonomy in lateral shoots can be described as their ability to grow independently of apical control by the apex of the branch. Autonomy of laterals near the branch apex increased with their length. In `Zaigina' this was established via a more distal start of the second zone, and in `Mayglo' via an increased gradient in the second zone. The early loss or maintenance of apical control regulates architecture in sylleptically branched peach and nectarine shoots. Crotch angle widening of laterals appears to be largely dependent on position, but in some cultivars, such as `Mayglo', other factors are also involved. The data provide evidence of correlative phenomena between actively growing shoots.