Population Of Cv Research Articles

Salt tolerance in natural populations of Trifolium repens L.

SUMMARYThe salt tolerances of plants from natural populations of Trifolium repens L. (White Clover) growing in saline and non‐saline sites were compared by root growth tests at a range of NaCl concentrations. Plants from three salt‐marsh sites showed high or very high salt tolerance, with relatively vigorous root growth in 150–200 mM NaCl. Plants with two non‐saline inland sites showed little or no tolerance. A sea‐cliff population and plants of cv. Gwenda showed intermediate levels of tolerance at low salt concentrations. Halophytic maritime populations may‐provide material for the development of salt tolerant cultivars of T. repens, a crop plant in which most existing cultivars are thought to be salt‐sensitive.

Natural male sterile mutant in hot chilli (Capsicum annuum L.)

A natural male sterile mutant was recovered from the normal population of chilli cv. CA 452-1. The male sterility in the mutant was governed by a single recessive gene ms. The excessive vegetative growth provided easy identification of male sterile plants in the seedling stage. The plant was found to be promising for hybrid seed production.

Field evaluation of lucerne cultivars for resistance to blue–green lucerne aphid and pea aphid (Acyrthosiphonspp.) in New Zealand

Abstract Population density and aphid feeding damage scores of Acyrthosiphon kondoi Shinji(blue–green lucerne aphid) were significantly lower, and dry matter yield of forage was higher, in lucerne cv. Rere than in cv. Wairau or cv. Saranac grown in field trials. ‘Rere ‘is apparently resistant to colonisation and utilisation of the plant by A. kondoi, and is tolerant of aphid feeding damage. Populations of cv. Saranac and ‘CUF 101‘selected for resistance to A. kondoi were also resistant to this species and tolerant of feeding damage.Population density of Acyrthosiphon pisum Harris (pea aphid) was probably too low to be damaging and no consistent cultivar effects on numbers were found.

The effects of temperature and light energy on dry weight and leaf area changes in seedling plants of Lolium perenne L

Nine identical seedling populations of Lolium perenne cv. Grasslands Ruanui were grown at different times in a controlled environment cabinet under 22, 38, and 117 watts m-2Visible radiation (16 hr day length) and at 10, 20, and 30�C for 32 days. The proportion of the total dry matter present as roots and that of the shoot dry weight present as leaf laminae were only slightly affected by the environment. Shoot growth was dominated by leaf growth; responses to the environment of the average relative growth rate (El,) and the average leaf area growth rate RA) were similar. RW and RA were maximal at 20�C at each light flux density and increased toward a maximum with increased radiation at each temperature. Maximum RW for seedling plants of L. perenne was about 25% per day. The net assimilation rate increased approximately linearly with increase in light flux and was scarcely affected by temperature. The leaf area ratio was greatly affected by changes in light energy, mainly owing to change in the specific leaf area. The rate of leaf appearance was accelerated by a temperature increase from 10 to 20�C. Total tiller number was maximal at 20�C and increased with light flux. When related to leaf number, tillering was reduced only by high temperature at low light energy. The relative changes in net assimilation rate induced by variation in light flux at 20�C were the same as those in the net photosynthesis of a single leaf lamina. The growth of seedling ryegrass plants in the field in winter is considered to be strongly dependent on temperature and much less restricted by low light energy.