Do the stage of plant and initial population of root knot nematode influence on sweet pepper development?

The aim of this study was to investigate the response of three different stages (one, three and five leaf pairs) of sweet pepper (Capsicum annuum cv. Orazio) seedlings to five inoculation levels of Meloidogyne enterolobii (zero (control), 300, 1000, 3000 and 10000) under greenhouse conditions. Each plant was cultivated in one pot filled with 3.8 L of substrate. The test was a completely randomized design with four replications. The plants were assessed 60 days after inoculation, plant shoot weight, final population of nematodes, and reproduction factor were measured. The results were fitted to Seinhorst model: Y = m + (1-m). ZPi –T. The results showed a tolerance limit (T) of 2,500 nematodes for plants with one and three leaf pair, and 8,500 nematodes for the five-leaf pair plant.

Pruning for crop regulation in high density guava (Psidium guajava L.) plantation

High density management and crop regulation are two important aspects in guava (Psidium guajava L.) production. Therefore, to find out the economic way of managing high density planting and crop regulation, the present work was carried out on 6-year-old guava trees of cv. Pant Prabhat under double-hedge row system of planting during 2009-10 and 2010-11. Seven different forms of pruning [FBT: flower bud thinning by hand, FBTT: flower bud thinning by hand followed by removal of terminal one leaf pair, RLFO: removal of leaves and flower buds by hand, retaining one leaf pair at the top, RLF: removal of all leaves and flowers by hand, OLPS: one leaf pair shoot pruning, FSP: full shoot pruning, OLPF: one leaf pair pruning of fruited shoots only] were studied along with control (C).Minimum annual increase in tree volume (6.764 m3) was recorded with the treatment OLPF, which was 2.31 times less than the control (15.682 m3). Highest yield during winter season (55.30 kg/tree) and total yield (59.87 kg/tree) was obtained from treatment OLPF. One leaf pair pruning of fruited shoots only (OLPF) was also found profitable among other treatments by recording cost:benefit ratio of 1:2.96. This treatment also recorded the highest return distributed in rainy as well as in winter season. On the basis of findings it can be concluded that one leaf pair pruning of fruited shoots only is suitable for profitable high density management as well as crop regulation of guava in farmer friendly manner.

Postemergence Herbicides for Calendula

Calendula is an alternative oilseed crop whose seed oil is valued as a substitute for tung oil and a replacement for petroleum-based volatile organic compounds in paints and other coatings. Calendula tolerances to most POST-applied herbicides are unknown. Two POST-applied herbicides were tested for tolerance by calendula. Imazamethabenz at 0.44 kg ai ha−1 plus surfactant and desmedipham plus phenmedipham at 0.36 + 0.36 kg ai ha−1 were tolerated by calendula, but the latter herbicide must be applied after the four–leaf-pair stage of growth to avoid severe injury. Neither herbicide adversely affected calendula seed yield if applied at the four–leaf-pair stage. Because these herbicides can control several weed species, calendula tolerance to them may encourage more growers and crop advisors to test this new oilseed crop on commercial farms.

Partitioning of nitrate reductase activity in Coffea arabica L. and its relation to carbon assimilation under different irradiance regimes

The distribution of in vivo nitrate reductase (EC 1.6.6.1) activity (NRA) between leaves and roots was studied in young coffee plants (Coffea arabica L.) grown in pots with watered sand in a glasshouse and irrigated with nutrient solution. The influence of irradiance regimes on the partitioning of NRA, and its relation with CO2 assimilation, was also evaluated in plants grown under approximately 20, 50 and 100% of full sunlight. Time-course of nitrate accumulation in nitrogen-starved plants showed a similar pattern in leaves and roots after supplying 15 mmol L-1 nitrate, indicating efficient ability of the roots to export nitrate to the shoot. At the same time, NRA was rapidly induced in both tissues. In shoots, NRA partitioning was synchronized among the various leaf pairs. The initial increase in NRA, as each leaf pair emerged, coincided with the optimum NRA values of the next older leaf pair. However, the average shoot NRA remained relatively constant for each sampling date. During the first 23 weeks of vegetative growth, the mean NRA was 32% higher in leaves than in roots. The irradiance regimes influenced the partitioning of NRA between leaves and roots. The NRA leaf /root ratio was 0.72, 1.21 and 1.05, respectively, for plants grown under 20%, 50% and 100% of full sunlight. Leaf NRA was positively correlated with CO2 assimilation, in response to irradiance regimes. Under favorable CO2 assimilation conditions, higher NRA was observed in leaves than in roots, and the contrary trend occurred under limiting CO2 assimilation conditions. Under moderate irradiance regime the leaves were the main site of nitrate reduction, contributing with 70% of the whole plant nitrate assimilation.

Anisophylly in Aucuba japonica (Cornaceae): An outcome of spatial crowding in the bud

Anisophylly in Aucuba japonica Thunb. occurs exclusively in axillary buds on shoots of individuals that have reached reproductive maturity; juvenile plants or sprouts and shoots from terminal vegetative buds on adult plants are isophyllous. The initially smaller leaf primordium in each anisophyllous leaf pair gives rise to the larger final leaf size. Immediately before bud break, the size of the initially smaller primordium is already almost twice as large as the initially larger primordium, and the size differential is further amplified following bud break. The degree of aniso phylly, however, varies among the nodes of a shoot, depending on leaf pair orientation (tangential or parallel to the inflorescence axis) and nodal position. Paired leaves approach isophylly when they originate tangential to an inflorescence but become anisophyllous when originating parallel to an inflorescence. The degree of anisophylly depends on crown light conditions through effects on terminal bud size and foliage distribution on the shoot, but ultimately appears to arise from space limitations and crowding between the leaf primordia and the developing inflorescence in terminal reproductive buds.Key words: Aucuba, anisophylly, bud internal morphology, developmental anatomy, developmental constraints.