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Abstract
By far the most important subtropical fruit is citrus and the most widely grown citrus is the sweet orange. Lemon and grapefruit also are important citrus species. Other important subtropical fruits are dates, figs, and olives. Tropical fruits are most numerous in kinds, and a few, such as the avocado, litchi and mango are grown on a commercial scale in the subtropical regions. Others, such as bananas, pineapples, coffee, and papaya, are strictly tropical. It is not an uncommon practice to apply K, but it is done in many cases without a demonstrated need. With the realization of the broad effects of K, such a practice should not be followed, but K level should be adjusted to give optimum response for both quality and yield. For this diagnostic methods and standards are required.
Abstract
An increase in the K level in orange and grapefruit trees generally increases the thickness of the peel and reduces the percentage of juice in the fruit. Data presented in this report show that an increase in K in the lemon tree has the opposite effect as that which occurs in the orange and grapefruit tree. An increase in the level in lemon trees resulted in thinner peels and in a higher percentage of juice in the fruit.
Abstract
A simple-leaved pecan [Carya illinoensis (Wang.) K. Koch] seedling was found in a Riverside seedling nursery by Larry Womack of Womack Nurseries, DeLeon, Texas. This uncommon specimen was preserved by grafting it to a normal pecan seedling rootstock sometime in the early 1960’s. Wood from the variant was grafted on orchard seedlings at the U. S. Pecan Field Station, Brownwood, Texas, in April 1973 and on 1-year-old greenhouse-grown Riverside seedlings in Feb. 1974. This paper reports observations of the growth and gross morphology of this unusual variant.
Abstract
Suitable parents for the production of F1 hybrid seed between almond and root-knot nematode resistant peach were selected. Three of 13 almond selections were found which, when pollinated by ‘Nemaguard’ pollen, produced good sets of seed. When germinated, their seedlings showed good root-knot nematode resistance, hybrid vigor, and exceptional compatibility with almond tops.
The self-incompatibility of almond was used to permit natural pollination between selection CP5-33 and a selected seedling of ‘Nemaguard’, 3-28. The F1 hybrids proved to be very compatible as rootstocks with almond and peach tops and imparted increased vigor to them.
Both ‘Nemaguard’ and a selected seedlings of ‘Nemaguard’ served as good pollen parents. ‘Okinawa’ peach, another rootknot nematode resistant peach type rootstock, was a less satisfactory pollen parent.
Abstract
Starch in the roots of mandarin trees (Citrus reticulata Blanco cv. Kinnow) was drastically reduced by an “on” crop. This was related to prolonged bud dormancy, delayed spring growth and an “off’ crop the following year.
Abstract
Where Mg deficient ‘Washington’ navel orange trees were sprayed with Mg, leaf Mg was increased from a deficient to an optimum level in the first year of application. However, it was not until the fourth year of application that a yield increase occurred. At least 2 sprays annually were required. There was an increase in total soluble solids in the juice as a result of the sprays, but there were no other consistent effects on fruit quality. Magnesium in the feeder roots was increased by the foliage sprays. Leaf K was decreased by the Mg sprays. One year after cessation of the sprays the leaf Mg was again in the deficiency range.
Abstract
In a 5-year factorial fertilizer experiment, an increase in leaf N from 2.54 to 2.71% by soil applications of urea, reduced creasing and fruit size and increased green color on the fruit at harvest. Leaf K was increased from 0.47 to 0.67% by soil application of K2SO4 and to 0.65% by foliar application of KNO3; except for degree of fruit color and leaf N content, effects of soil- and foliar-applied K differed little and both increased yield, fruit size, and green color on the fruit and reduced creasing. Increasing leaf P from 0.132 to 0.139% had little influence on factors influencing the value of the fresh-fruit crop. Gibberellic acid (GA) sprays increased green color on the fruit and reduced creasing. The effects of N, K, and GA on reducing creasing and increasing green color on the fruit were strongly additive. There was an inverse relation between creasing and green color of fruit. Each problem can be reduced but at the expense of the other, and both problems cannot be reduced simultaneously. Packinghouse statements showed that monetary returns/tree were increased about 75% by K treatments without GA; 17% with GA alone; 61% with GA + soil-applied K; and 42% with GA + foliar-applied K.
Abstract
Field experiments in the past on Valencia orange trees in California have not shown any clear K deficiency as indicated by the effects of K applications on numbers of fruit produced per tree. Such experiments were established with little knowledge of the initial K nutritional status of the trees in question. Commercial use of citrus leaf analysis as a diagnostic tool has increased in recent years, and through this medium an orchard was found near Escondido, California with leaf K levels which indicated possible K deficiency. Some of the initial results of an experiment in this orchard are given in Table 1.
Lycopersicon pennellii accession LA 1277 was crossed to tomato (L. esculentum) and the F1 was backcrossed to tomato. Self-pollinated seed was saved from backcross plants and seedlings derived were inoculated with Fusarium oxysporum Schlecht f.sp. radicus-lycopersici Jarvis and Shoemaker, the causal agent of Fusarium crown and root rot (FCRR). Seed was saved from resistant plants that were self-pollinated and screened until homozygous resistance was verified five generations after the backcross. Three homozygous lines were crossed to Fla. 7547, a tomato breeding line susceptible to FCRR but resistant to Fusarium wilt races 1, 2, and 3. Subsequently, backcrosses were made to each parent and F2 seed were obtained. The three homozygous FCRR-resistant lines were also crossed to Ohio 89-1, which has a dominant gene for FCRR resistance presently being used in breeding programs. F2 seed were obtained from these crosses. These generations were inoculated with the FCRR pathogen. The resistant parents, F1, and backcross to the resistant parents were all healthy. The backcross to the susceptible parent and the F2 segregated healthy to susceptible plants in 1:1 and 3:1 ratios, respectively. Thus, the resistance from LA 1277 was inherited as a single dominant gene. This gene was different than the gene from Ohio 89-1 because susceptible segregants were detected in the F2 generation derived from the two resistant sources.
Forty-two Lycopersicon pennellii Corr. D'Arcy accessions, from the Tomato Genetics Stock Center, were inoculated for resistance to Fusarium wilt race 3 at the 3-leaf and cotyledon stage. All were over 90% healthy when inoculated at the 3-leaf stage but had greater disease incidence at the cotyledon stage. Crosses were made between healthy plants within each accession. Using this seed, 39 accessions were 100% healthy and 3 were over 96% healthy when inoculated at either stage. Seventeen F1's with susceptible parents were tested for race 3 and all had over 80% healthy plants. Twenty-two accessions were tested for Fusarium wilt race 1 and race 2. For race 1, 21 were 100% healthy and 1 was 91% healthy, For race 2, 20 were 100% healthy, 1 was 96% healthy, and 1 was 75% healthy. Forty accessions were screened for Fusarium crown rot and Verticillium wilt. For crown rot, LA 1277, LA 1367, and LA 1657 were over 95% healthy, 6 other accessions were over 68% healthy and several others had over 50% healthy plants, All 40 were susceptible to Verticillium wilt race 1. L. pennellii appears to be a good source of resistance to Fusarium sp. but not to Verticillium wilt.